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THE
SURGICAL ANATOMY
OF THE
HORSE
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THE
SURGICAL ANATOMY
OF
THE HORSE
BY
J. T. SHARE-JONES, M.Sc, F.R.C.V.S.
SECRETARY OF THE BOARD OF VETERINARY STUDIES, HEAD OF DEPARTMENT OF VETERINARY ANATOMY AND
LECTURER ON VETERINARY SURGERY AND MEAT INSPECTION, UNIVERSITY OF LIVERPOOL
EXTERNAL EXAMINER FOR THE DEGREE OF B.SC, UNIVERSITY OF ABERDEEN ; INTERNAL EXAMINER
FOR THE D.V.H., UNIVERSITY OF LIVERPOOL
REPRESENTATIVE GOVERNOR OF THE UNIVERSITY COLLEGE OF NORTH WALES ; MEMBER OF THE JOINT AGRICULTURAL
EDUCATION COMMITTEE FOR DENBIGHSHIRE AND FLINTSHIRE J MEMBER OF COUNCIL AND VICE-PRESIDENT,
ROYAL COLLEGE OF VETERINARY SURGEONS ; EDITOR IN-CHIEF, "VETERINARY NEWS," ETC.
PART IV.
LONDON
BAIL LI ERE, TINDALL MD COX
8 HENRIETTA STREET, COVENT GARDEN
1914
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PREFACE TO PART IV
In tendering to the subscribers my apologies for the delay in issuing the
concluding volume of " The Surgical Anatomy of the Horse," I can only-
state that it is due to circumstances over which, unfortunately, I have
had no control.
The publishers' rights for the whole of the work have been
acquired by Messrs. Bailliere, Tindall and Cox, and their close connec-
tion with the veterinary profession will render the work easily accessible
to its members.
The majority of the illustrations throughout the work are original,
and have been taken from my own dissections. Plate II. in Volume III.
is after Stubbs, but slightly modified. The remaining plates which are
not original have, it is hoped, been duly acknowledged. For most
valuable assistance in executing the coloured illustrations I wish to
express my indebtedness to Mr. G. F. S. Boston, whose eminence as an
artist I venture to hope will be in no way detrimentally affected by the
work which has been reproduced. No pains have been spared by
Mr. Boston and myself to depict as truly as possible the parts as they
have appeared to us.
My friend Professor Macqueen has again revised the proofs as they
were passed for press. His suggestions have been valuable, his criticisms
and corrections many, and to him, as on previous occasions, I wish to
express my sincere thanks. My thanks are also due to my former
demonstrator, Mr. C. W. Makinson, M.R.C.V.S., and to Mr. Harold
Quiggin, M.R.C.V.S., for assistance in compiling the index and some of
the tables.
V
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PREFACE TO PART IV
vi
My gratitude to those British and foreign colleagues who have been
kind enough to express their appreciation of the preceding volumes is
unbounded. If, as stated by a distinguished French confrere, I have been
successful in demonstrating the necessity which existed for a work of this
kind, then my object will have been accomplished. A more detailed
application of anatomy will, of necessity, be required as surgery develops.
It is hoped that this effort will stimulate others in the work of establish-
ing further the relationship between these two fundamental subjects.
To the Vice-Chancellor of the University of Liverpool I am
grateful for his kindly encouragement throughout. Every required
facility has been generously placed at my disposal.
In conclusion, I venture to hope that this volume will prove, both
at home and abroad, as acceptable as its predecessors to students and
practitioners alike.
JOHN SHARE-JONES.
School of Veterinary Science,
The University of Liverpool.
October, 1914.
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CONTENTS
PART IV—FOOT AND TRUNK
CHAPTER
I. THE FOOT .
PAGE
......I
II. THE THORAX AND BACK
.........62
III.  THE ABDOMEN, LOINS, ETC. .                                                           Io6
IV.  THE UROGENITAL ORGANS........ ,60
V. THE HEART, BLOODVESSELS, AND LYMPHATICS ... 231
MUSCLES OF THE TRUNK
........246
INDEX         ....
. 251
vii
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ILLUSTRATIONS
COLOURED PLATES
FACING PAGE
ft
Interior of Hoof (freshly removed) ......
Fresh Specimen of Foot with Hoof removed (Anterior Aspect)
I a. Posterior Aspect of Digit, showing Digital Arteries (after ^
BOULEY, MODIFIED) .........
b. Transverse and Vertical Section of Foot, showing Position of
I,
y i;
Lateral Cartilages.........
c Section showing Plantar Cushion, Os Pedis, Lateral Cartilage,
etc............ • •'
VI. Sagittal Section of Foot.........52
X. The External Inguinal Ring (Left) with Part of Left Inguinal
Canal exposed...........I2°
XI. The Pelvic Inlet in the Male........I24
XV \a' ^EAT 0F Urethrotomy.........\ .
\b. Transverse Section of Tail, showing Principal Vessels and Nerves J
XVII.
fa. Le* t Testicle withdrawn from Scrotum.....
J74
'{/>. Transverse Section across Left Inguinal Canal (Semischematic)
XXII. Female Genital Organs.........222
HALF-TONE PLATES
II. Transverse Section through Inferior Half of Os Corona
[a. Outline of Left Lateral Cartilage (Left Fore Foot) .
III.-j b. Right Lateral Cartilage Exposed (Right Fore Foot) .
[c. Phalanges and Lateral Cartilage (Schematic)
V. Smith's and Bayer's Operations ......
VII. Vertical and Transverse Section through Wall of Thorax
12
16

68
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x                                    ILLUSTRATIONS
PLATE                                                                                                                                                                                                                                                 FACING PAliE
VIII. Notch in Left Lung exposing Pericardium......       82
IX. Vertical and Transverse Section through Withers ....       88
XII. Wall of Abdomen removed, showing Intestines.....     130
XIII.   Seat of Operation in Laparo-Enterotomy . . . . .              134
XIV.    Pelvic Inlet in the Mare . . .......     144
XVI. Coverings of Left Testicle incised.......     172
XVIII. Testicles in situ...........     176
XIX. Portion of Ilium and Walls of Pelvic and Abdominal Cavities
removed, showing Rectum, Vagina, Uterus, Bladder, and Right
Ovary ............     206
XX. Incision in Wall of Vagina, showing Position of Os Uteri . .     208
XXI. Ovariotomy ............     212
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CHAPTER I
THE FOOT
In equine anatomy, the term foot is applied to the hoof and the parts
which it contains.
THE HOOF
he hoof is divided into four parts, named respectively the wall,
bars, sole, and frog.
e Wall.---This is sometimes called the crust, and is the name given
to that portion of the hoof which is visible when the foot rests on the
'          • superficial examination of its exterior in the foot of a young
animal which W * u
nas not been shod will reveal the fact that it is covered
iny ayer — the periople — which has very appro-
pnately been termed «a kind of epithelial varnish.» It forms an
efficient protective covering, and its presence prevents excessive evapora-
tion. It is commonly rasped away during shoeing—a practice which is
to be condemned, since the removal of the periople causes the hoof to
ecome brittle, and predisposes to the formation of fissures in the wall,
sandcracks, etc. The periople is thickest'towards the upper limit of the
wall where it may be traced around the wall just below the hair. It is
developed from the so-called perioplic ring. The wall is divided into
toe quarters and heels, the toe being placed anteriorly and consisting of
an area on either side the median line. The quarters are placed one on
either Side behind the toe, whilst the heels are placed posteriorly one
A
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PLATE I.—A.—Interior OF Hoof (freshly removed).—i. Cutigeral groove. 2. Horny lamina;. 3. Frog stay. 4. Frog. 5. Horny laminre.
B.—Fresh specimen of Foot with Hoof removed (anterior aspect).—1. Coronary cushion. 2. Sensitive laminae. 3. Smooth area between 1 and 2. 4. Perioplic ring.
C.—Inferior aspect of Hoof.—1. Heel. 2. Frog. 3. Bar. 4. Lateral lacuna. 5. Sole. 6. Point of frog. 7. Toe. 8. Wall. 9. White line. 10. Seat of corn.
11. Median lacuna. 12. Wall recurving to form bar.
To face page 4.
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2            THE SURGICAL ANATOMY OF THE HORSE
behind each quarter. There are no well-marked lines of division between
these parts. At the toe the wall is thicker than at the quarters or heels,
and the outer portion of the wall is thicker than the inner. The wall of
the fore foot slopes obliquely downwards at an angle of about forty-five
degrees. That of the hind foot more nearly approaches the vertical, the
angle formed being approximately one of fifty degrees.
The inner surface of the wall presents superiorly a well-marked
trench, which runs transversely. This is the cutigeral groove, and it
receives the coronary cushion. At the bottom of the depression there
will be observed a large number of tiny perforations. These are the
entrances to the horn tubes, and are for the accommodation of the papillae
of the coronary cushion. Below the cutigeral groove are the horny
laminae, of which there are from five to six hundred. These are leaf-like,
and are disposed vertically. They are whitish in colour and interleave
with the sensitive laminae. The inferior border of the wall comes into
contact with the ground, and in the unshod hoof is subjected to wear.
It embraces the sole; but the division between the wall and sole is very
evident, since there exists between them a layer of cells which are
unpigmented, and which form what is known as the white line.
The Bars.—If the wall be traced backwards, it will be found to curve
at first towards the median line, and then forwards on either side. These
forwardly curved portions of the wall constitute what are known as the
bars, and the bends where they become continuous with the wall form
the heels. The inferior border of the bar, as in the case of the wall,
bears weight. The concentric surface of each bar forms the outer
boundary of the corresponding lateral lacuna of the frog, whilst the
remaining lateral surface carries horny laminae similar to those found on
the deep face of the wall. In a foot which has been properly prepared
to carry a shoe, it will be noticed that the bar is thickest towards its
posterior extremity, and that its thickness gradually diminishes from
behind forwards to its anterior limit, which is placed behind the point
of the frog. Superiorly the bar becomes blended with the frog and sole.
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Plate 11.-Transverse Section through Inferior Half of Os Corona (after Ellenberger,
slightly modified).
I' TH°of- . 2- Tendon of extensor pedis. 3. Os corons. 4. Lateral ligament of corono-pedal joint.
bordPreraf cartila?e. 6. Synovial membrane of corono-pedal joint. 7- Ligament attached to upper
Q Svnn,°- ,na™ular bone, sometimes called the navicular suspensory ligament. 8. DJgital artery.
9- Synovial sheath. 10. Lateral cartilage. 11. Tendon of flexor perforans. 12. Plantar cushion.
13. Digital nerve.
To face page 12.
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THE HOOF                                               3
The area included between the bar and the wall is extremely
important, inasmuch as it is the seat of corn. The bars are gener-
ally supposed to afford a considerable degree of stability to the foot, and
great care should be directed towards their preservation when removing
a portion of the sole in this region, and particularly during the perform-
ance of the common operation of " cutting out " a corn.
The Frog.—This is the portion of the hoof which is wedged in
between the bars. It is composed of elastic horny tissue, and its
inferior surface should come into contact with the ground. It thus acts
as a natural flexible pad which is effective in limiting the concussion
thrown upon the limb during progression.
Its inferior surface presents posteriorly a depression called the median
lacuna, the depth of which varies, but in a well-formed hoof it is
relatively shallow. This depression is bounded by two rod-like portions,
sometimes referred to as the bars of the frog, but which must not be
confounded with the bars already described. These two portions become
narrower as we proceed forwards. In front of the median lacuna they
blend with each other, and, gradually tapering down, they terminate
anteriorly in a sharp projection called the point of the frog, which is
placed near the centre of the sole. The frog is thus somewhat triangular
in outline, the apex being at the point. The two sides form the inner
boundaries of two other depressions which are placed between the frog
and the bars. These depressions are the lateral lacunas, or commissures
of the frog. Superiorly the two lateral borders of the frog blend anteriorly
with the inner border of the sole, and behind this with the upper edges
of the bars. The posterior portion of the frog, which forms the base of
the triangle, consists of two large, rounded eminences called the frog
bulbs, and referred to by Bracy Clark and others as the glomes. These
are placed one on either side the median lacuna. They are highly elastic,
and are softer to the touch than the remainder of the hoof. They become
continuous postero-superiorly with the perioplic ring.
The superior surface presents immediately over the median lacuna,
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Plate III.—A.—Outline of Left Lateral Cartilage (Left Fore Foot).
B.—The Right Lateral Cartilage Exposed (Right Fore Foot),
i. Skin. 2. Antero-superior angle of cartilage. 3. Postero-superior angle of same. 4. Hoof.
          -»••■•«
cartilage.
6. Its antero-inferior
ang'e. 7- Its postero-inferior angle.
C.—The Phalanges and Lateral Cartilage (Schematic).
1. First phalanx (or suffraginis). 2. The pastern joint. 3. Second phalanx (os coronae). 4. The pedal joint. 5. Left lateral cartilage
phalanx (os pedis). 7. Navicular Bone.
6. Third
To face page 16.
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4            THE SURGICAL ANATOMY OF THE HORSE
and therefore in the middle line, a process which projects upwards and
backwards, and to which Bracy Clark gave the name "frog stay." There
is also present on this surface a depression which is somewhat triangular
in outline, and which is divided posteriorly into two lateral depressions
placed one on either side of the frog stay. For the rest of its extent this
surface is moulded on to the inferior surface of the plantar cushion, and
the papilla? of the latter are accommodated in the numerous puncta
which are scattered over this aspect of the frog.
The Sole is a plate-like piece of horn placed between the inner border
of the wall externally and the bars and anterior portions of the lateral
borders of the frog inwardly. Into it, as already remarked, the point of
the frog projects. The sole presents two surfaces, the inferior of which
is vaulted, and in outline approaches the crescentic. The degree of con-
cavity of this surface varies in different hoofs. In upright blocky feet it
is usually much more concave than in those which are broad and open.
This is the natural configuration of the surface, and is due to the manner
in which the superficial layers of horn exfoliate, and not to any use of the
drawing knife to which it might have been subjected. The surface is
more concave in hind hoofs than in fore. The anterior or external
border of the sole is convex. It is denticulated, and its small denticular
are interlocked with those of the inferior border of the wall. The wall
and this border of the sole are intimately united along what has already
been described as the white line. The posterior border shows a deep
V-shaped outcut, the apex of which accommodates the point of the frog,
whilst posteriorly on either side it is related to the bars.
The superior surface is correspondingly convex, and numerous puncta
are scattered over it. These accommodate the papilla? of the correspond-
ing sensitive portion of the foot.
Although the wall, sole, and frog, are intimately attached to one
another, they may be shown to be separate segments if the hoof be
subjected to maceration for a lengthy period.
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ia«dA™iJkalAa'rterIie0sSTE,RI0De^ZZ w T"' ™IKG DlG1TAL Aperies (after Bouley-modiFiED).
branch which anastomoses w^P branch ^ flexor tendons. 4. Superficial branches to fle
or
circle.
to flexor tendons
astomoses with corresoondinsr vesse from „,™™;*„ „:j___j r._.....
don ofZL7Z{oZlu ? ,%Z ^Z °PP?Slte side and forms anterior portion of coronary
.         tendons. c. Solar area of Ded.l £,„            * ^i*™ °f C°r°nary circle- 8" Posterior blanch distributed
ar* or anastomosis in semLnS sinus         r, T ', ^^ ^^ PaSsinS alonS P]ant» g™™. 11. Plantar
removed iTAscenH?^ E '" "^ sWinS where solar a«a "fpedal bone has been
cmoved. 13. Ascending and descending branches from plantar arch.
F^pha.arr^rTu^nf0LfPrt™Lnt F,oos sh7tc; posmoN °f latkkal
r Q               S               pastern joint. 3. Second phalanx. 4. Lateral cartilage.
Lateral carfflaj^S^^ CUSHI°^' °S MDIS' LATERAL CarTIlage
8 2. lantar cushion. 3. Frog. 4. Bar. 5. White line. 6. Sol
5. Third phalanx.
&c.
Wall. 8. Os pedis.
To face page 18.
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THE HOOF
5
Horn Tissue
The horny substance which constitutes the hoof is tough and fibrous.
This is particularly so in the case of the tissue of the wall. In the frog
and deeper portion of the sole its fibrous nature is not so apparent, whilst
in the superficial layer of the sole it becomes entirely lost, owing to the
continual disintegration of horn here and the separation of it in layers
from the parts beneath. The colour is usually black, but not infrequently
white. The depth of colour generally corresponds to that of the skin
enveloping the parts immediately above the hoof, for the hoof is simply
an appendage of the skin, and corresponds to its epidermal layer.
It has a much firmer consistency in the wall and sole than in the frog.
Microscopically it will be found to be made up of a number of minute
cylindrical tubes containing a quantity of intratubular material, and united
by what is known as the intertubular substance. The tubes and the
uniting and contained matter are made up of modified epithelial cells.
The tubes of the wall are arranged in parallel rows, and form a number
of layers superposed to one another, whilst internally we have a number
of plates, or lamella?. In addition there are distributed amongst these
various layers numerous cells containing a pigmented material. In the
frog the tubes have a different disposition, for they are arranged in a
flexuous manner. They are also much finer and more delicate than are
those of the wall and sole, which accounts for the greater degree of
elasticity possessed by this part.
PARTS WITHIN THE HOOF
I. The Keratogenous Membrane
This is exposed when the hoof is removed. To the inexperienced,
the effective removal of a hoof for the purpose of studying the underlying
parts presents considerable difficulty. If a fresh specimen is being utilized,
it should be placed in a fire, the part above the hoof being encased in wet
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Plate v.—Smith's and Bayer's Operations.
A.—i. Common seat of entrance to sinus in quittor. 2. Grooves in wall in Smith's operation
for sidebone. 3. Outline of portion of wall reflected upwards in Bayer's operation for quittor.
B.—Inferior aspect of foot, showing grooves in Smith's operation (x) and connecting groove (y).
To face page 50.
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6             THE SURGICAL ANATOMY OF THE HORSE
sacking or some other protective material. On withdrawing the specimen
from the fire, an incision is made around the limb at the junction of the
skin and hoof, the part is placed in a vice, and the hoof torn away with
a pair of strong pincers. This method has the advantage of being the
quickest way of exposing the parts, but it is rarely possible to remove the
hoof thus without destroying some of the delicate structures which it is
desired to keep intact. Maceration in water and burying in a manure-
heap for several days are other methods under which the hoof becomes
loosened by decomposition, and its removal facilitated. Although by
these methods some considerable time must elapse before the hoof can
be removed, they have an advantage over the first method in that there
is less danger of destroying the parts more deeply seated.
The keratogenous membrane spreads over the expanded portion of the
tendon of the extensor pedis just above its insertion into the pyramidal
process of the pedal bone, the laminal or anterior surface of the pedal
bone, and the anterior portion of its inferior surface. It also covers the
inferior half of the outer surface of each lateral cartilage, together with
the bulbs and pyramidal body of the plantar cushion. The membrane
envelops these parts as a foot is encased by a sock.
It is convenient to describe the keratogenous membrane in three parts :
A. The Coronary Cushion.—This is the structure which is accom-
modated in the cutigeral groove, already described, within the hoof. It
forms a rounded, cornice-like projection placed above the sensitive lamina?
or podophyllous tissue. To the touch the surface of the cushion feels
velvety. This is due to the presence of long papilla? on its surface.
These are very numerous, and pass into the apertures already mentioned in
connection with the cutigeral groove. If the part be immersed in water,
the papilla? become more apparent.
Posteriorly the coronary cushion becomes continuous with the plantar
cushion. Above its superior border is a narrow groove. This is shallow,
but nevertheless is quite distinct, and separates the upper margin of the
cushion from the perioplic ring. Between the inferior border and the
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Plate VI.—Sagittal Section of Foot.
r =„f o Ql^ - Tendon of flexor perforans. 4. Synovial bursa. 5. Tendon of
^J^STT^^S^^^S*. ^^'^^.r^t^anx:
o Sesamoid bone. K, Me^^ ^^^^^n^s^l^^,
13. Ergot. 14, 18 and 17 Deep, ™*£?^■ > e^ensor pcdis. K> Second phalanx or os corona.
20! S^olntr ^ iXhalangcIf^u^n.6. ,1 Third phalanx or os^edi, ^-gj^l
groove 23 Pouch of synovial membrane of coffin joint. _ 24. Coronary cushion. 25. Navicular bone.
26. Wall of hoof. 27. Plantar cushion. 28. Sensitive lamina:. 29. Horny frog. 3°- Sole.
To face page 52.
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PARTS WITHIN THE HOOF
7
upper extremities of the sensitive laminae is a narrow area which is smooth.
The cushion is thickest towards the front of the limb, and gradually
narrows down as it passes backwards.
The perioplic ring is placed above the coronary cushion, and its surface
is covered by papillae wrhich are somewhat smaller than those of the
coronary cushion. Through the agency of these papillae the perioplic
layer covering the wall is formed, whilst the papillae of the coronary
cushion secrete the horn tubules of the wall. It is important to bear the
latter point in mind in connection with the application of counter-irrita-
tion to the coronet to stimulate a better growth in those cases where the
quality of the horn is defective.
B. The Velvety TW.-This portion of the keratogenous membrane
covers the crescentic part of the inferior surface of the pedal bone and the
bulbs and pyramidal process of the plantar cushion. It follows closely
the contour of these parts, and is intimately adapted to their depressions
and elevations. Its inferior surface is related anteriorly to the superior
surface of the horny sole, and posteriorly to the corresponding surface of
orny frog. It is thus readily divisible into two portions, termed
jspectively the sensitive sole and the sensitive frog. The former
responds to the solar area of the pedal bone. In outline it is thus some-
what crescentic, with its convex border directed forwards. At the edge
parating the laminal and inferior surfaces it comes into apposition with
the inferior limit of the podophyllous tissue or sensitive laminae. At its
posterior extremities it becomes continuous with the plantar cushion, and
here it is slightly encroached upon by the laminae of the bars. The
inferior surface of this portion is concealed by the horny sole.
The portion termed the sensitive frog is placed centrally. In outline
it is somewhat triangular, with the apex directed forwards. Inferiorly
it responds to the superior face of the horny frog, and superiorly it is
related to the pyramidal body and bulbs of the plantar cushion. Posteri-
orly it becomes continuous with the coronary cushion and the perioplic
ring, but more particularly the latter.
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Plate VII.—Vertical and Transverse Section through Wall of Thorax.
I. Skin at withers. 2. Seventh dorsal spine. 3. Muscular layers at withers. 4. Scapula. 5. Spinal
cord'in neural canal. 6. Body of seventh dorsal vertebra. 8. Longus Colli muscle. 9. Oesophagus.
10. Trachea. 11. Great vessels entering or leaving chest. 12. Muscles of chest wall. 13. Internal
thoracic artery. 14. Triangularis sterni muscle. 15. Sternum. 16. Floor of thorax (note distance
of this from inferior cutaneous surface).
To face page 68.
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8             THE SURGICAL ANATOMY OF THE HORSE
The minute structure of the velvety tissue is very similar to that of
the coronary cushion. Jt possesses a vascular groundwork or corium with
a thickened fibrous periphery. This latter is in the form of a network,
which is termed the plantar reticulum, through the spaces in which
the veins forming what is sometimes called the solar or plantar plexus of
the foot run.
The velvety tissue presents on its surface papilla? or villi similar to
those on the coronary cushion, and these are accommodated in the minute
cavities of the horny sole and frog. The longest villi are found at the
periphery, and the shortest towards the centre. The papilla? of the
sensitive sole give rise to the horny sole, and those of the sensitive frog
to the tissue of the horny frog.
C. The Podophyllous Tissue, Sensitive Lamina, or Laminal Tissue.—This
is the portion of the keratogenous membrane which covers the anterior
or laminal surface of the pedal bone. It covers the whole of the surface
with the exception of a small smooth area on the anterior surface of, and
just below, the pyramidal process. The superior limit of this portion of
the membrane is indicated by the inferior border of the coronary cushion,
with which it is continuous, and it extends inferiorly to the convex edge
which separates the laminal and solar areas of the bone. It is thus widest
in front, and becomes progressively narrower as it extends backwards
towards the wings of the bone. On its surface there will be observed a
large number (from five to six hundred) of delicate ridges. These are the
lamina?, and from them this portion of the membrane is usually named.
The lamina? are distinctly separated from one another by deep clefts.
Their posterior borders are attached to the periosteum covering this surface
of the os pedis. The lamina? run obliquely downwards from the line
which indicates the inferior limit of the coronary cushion to the sharp
inferior edge of the pedal bone. Here each terminates in five or six long
papilla?, which are accommodated in the horny tubules at the periphery
of the sole. Each lamina carries on its lateral surfaces a number of delicate
secondary lamina?.
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Plate VIII.— Notch in Left Lung, exposing Pericardium.
i. External intercostal muscle. 2. Internal ditto. 3. Posterior border of fourth rib. 4. Left lung. 5. Notch in lung. 6. Pericardium.
7. Fifth rib. 8. Serratus magnus muscle. 9. Obliquus abdominis externus muscle.
To face page 82.
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PARTS WITHIN THE HOOF                             9
When the hoof is in situ the sensitive laminae are accommodated in
the spaces between the horny laminae, whilst the posterior members
of the series on either side, which are, of course, the shortest, are inter-
leaved with the horny laminae of the bars.
The sensitive laminae are the seat of the common affection known as
laminitis. They correspond to the corium, or true skin, and are responsible,
according to some writers, for the growth of the inner layer of the wall.
II. The Complementary Apparatus of the Pedal Bone
This consists of the two plates of cartilage known as the Lateral
Cartilages of the third phalanx, united posteriorly and inferiorly by the
fibro-elastic pad designated the Plantar Cushion.
A. The Plantar Cushion.—This is the name given to the wedge-like
structure interposed between the two lateral cartilages. For the purposes
of description, it may be said to present two surfaces, two edges or
borders, a base, and an apex. The superior face looks upwards and
forwards, and is closely applied to the lower face of the expanded inferior
extremity of the tendon of the flexor perforans muscle. The inferior
surface looks downwards and backwards, and its contour responds
accurately to that of the superior surface of the horny frog. The
pyramidal body which is the central portion of the cushion is frequently
referred to as the sensitive frog. It presents posteriorly in the middle
line a deep cleft for the accommodation of the frog stay. The two ridges
which bound the cleft meet in front. The apex lies in front of the semi-
lunar crest of the terminal phalanx, and the tissue of the cushion here
blends with the periosteum of the bone. The base is placed posteriorly,
and presents what are known as the bulbs of the plantar cushion. These
are two thick and rounded elevations placed one on either side, and to
them the ridges bounding the median cleft are prolonged backwards.
Outwardly each bulb becomes confounded with the posterior portion of
the corresponding lateral cartilage. The lateral borders of the cushion are
-ocr page 26-
Plate IX.—Vertical and Transverse Section through Withers.
I. Skin and subcutaneous fascia. 2. Funicular division of Hgamentum nuchas. 3. Fourth dorsal spine. 4 and 5. Layers of muscle. 6. Scapula.'
7. Arch of fourth dorsal vertebra.
To face page 88.
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io          THE SURGICAL ANATOMY OF THE HORSE
related to the inner surfaces of the lateral cartilages. Papillae are present
on the inferior aspect of the sensitive frog, and these are accommodated in
the foramina on the upper surface of the horny frog. It is through the
agency of the cells which cover the papillae that the horny frog is
formed.
B. 'The Lateral Cartilages.—These are frequently referred to as fibro-
cartilages. According to McFadyean, they are mainly composed of
hyaline cartilage showing a more or less fibrous matrix at the periphery.
Each cartilage presents two surfaces, four edges, and four angles. The
outer surface is convex, and is covered by a network of veins many of
which pass through foramina penetrating the thickness of the cartilage,
and communicate with the veins which form a plexus on its deeper face.
This latter surface is correspondingly concave. Its anterior portion
covers and protects the joint formed between the second and third
phalanges. This part comes into direct relationship with a small diver-
ticulum of the synovial membrane, a point which is of considerable
surgical importance, and which should be carefully borne in mind when
excising a portion of the cartilage in the treatment of quittor. For the
remainder of its extent this surface is attached to the plantar cushion.
The upper border is usually slightly convex, but occasionally is quite
straight. It is thin, may be readily bent, and can be felt in the living
animal without difficulty. Over this border the digital vessels run in
their course to the foot, and in some cases there is present a notch in the
cartilage for their reception. The inferior border is attached at its
anterior extremity to the basilar process, and behind this to the retrossal
process. For the remainder of its extent this edge blends with the
plantar cushion. The anterior border is the least extensive of the four.
It inclines downwards and backwards, and it blends intimately with the
more anterior of the two lateral ligaments of the corono-pedal joint. The
posterior border also runs downwards and backwards. It slightly exceeds
the anterior border in length, and is parallel to it. It blends with the
plantar cushion. The above four borders meet, forming four angles, of
-ocr page 28-
-
Plate X.—The External Inguinal Ring (left) with part of Left Inguinal Canal exptesticle in scrotal sac. 4. Left testicle in tunica vaginalis. 5. Plexus of veins. 6. Entrance to sheath.
Fold of skin on inner aspect of right thigh. 2. Ditto at right flank. 3. Right
7 and 9. Superficial nerves. 8. Left spermatic cord. 10. Inguinal nerves. 11. Posterior
or inner angle of external inguinal ring. 12. External pudic vein. 13. Tendon of obliquus abdominis externus muscle. 14. External pudic artery. 15. Posterior border of external inguinal ring.
10. ^remaster muscle. 17. Foupart s ligament. 18. Anterior edge of cutaneous incision hooked forwards. 19. Interior of left inguinal canal. 20. Anterior border of external inguinal ring. 21. Skin
on inner side of left thigh. 22. Obliquus abdominis internus muscle. 23. Anterior or outer angle of external inguinal ring.
ift. • 1iJ'?-—d,c"P}y ,tlle Parts the anterior edge of the cutaneous incision has been hooked well forwards. The spermatic cord has been drawn well out and hooked so as to be made tense. The
lelt testicle has been hooked over to the right side. The left hind limb has been drawn backwards to the fullest extent, and the posterior edge of the external inguinal ring hooked well backwards.
Ine plexus ot large veins at the ring (see text) has been hooked aside. The effect of drawing the hind limb and edge of the ring backwards is that the long axis of the ring is disposed almost
transversely. Ordinarily its disposition is more obliquely forwards and outwards.
To face page 120.
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PARTS WITHIN THE HOOF
11
which the antero-inferior and postero-superior are obtuse and the remain-
ing two acute. Posteriorly the cartilage curves inwards.
The surgical importance of the lateral cartilages cannot be too
strongly emphasized. They are the seat of the extremely common
afFection known as sidebone, and are concerned in several operations on
the foot, notably those adopted in treating quittor. The position and
flexibility of the superior border should be accurately determined by
manipulation of the limb in the living animal, and the observer will
find it a useful exercise to trace out the whole cartilage on the exterior of
the limb, in doing which a reference to Plate III. will be found helpful.
The degree of flexibility possessed by a cartilage can be ascertained best
by taking the foot off the ground, and allowing the anterior surface of the
wall to rest in the palms of both hands. The thumbs are then applied
one to the upper border of each cartilage, and pressure directed towards
the median line of the limb.
The cartilages of the fore feet are larger and thicker than are those of
the hind feet.
These structures are peculiar to solipeds.
III. The Bones and Joints
The Second Phalanx, Small Pastern Bone, or Os Coronae, was described
in Part II.
The Third Phalanx, or Os Pedis
This is also frequently referred to as the pedal, or coffin bone. It is
the terminal bone of the digit, and is accommodated entirely within the
hoor, to the general shape of which it to some degree corresponds.
it presents for description three surfaces, three edges, and two angles
or wings.
1 he surfaces may be designated anterior, superior, and inferior, and the
edges or borders, antero-superior, postero-superior, and inferior.
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Plate XL—The Pelvic Inlet in the Male.
(Most of the important structures on the leftside have been dissected out.)
Fourth lumbar superior spine. 2. Middle gluteus muscle. 3. Fourth lumbar transverse process.
Sublumbar muscles. 5. Interior of pelvic cavity. 6. Rectum. 7. Bladder. 8. Spermatic artery.
12. Vas deferens.
Internal oblique muscle of abdomen. 10. Inguinal nerves. II. Brim of pelvis.
13. Prepubic artery. 14. Internal abdominal ring. 15. Spermatic cord in upper portion of ing
it forms anterior
oblique muscle reflected where
!. Posterior abdominal artery.
canal. 16. External pudic artery. 17. Internal
boundary of inguinal canal. iS
To face page 124.
-ocr page 31-
12           THE SURGICAL ANATOMY OF THE HORSE
The Anterior Surface. — This is also termed the laminal surface,
since on this aspect is found that portion of the keratogenous apparatus
which carries the sensitive laminae. The surface is markedly convex
from side to side, and from the base of the pyramidal process downwards
to the inferior border it is almost straight. To the touch it is distinctly
rough, owing to the presence of numerous tiny osseous ridges. The
surface will also be observed to be pierced by a large number of foramina,
one of the largest of which on either side is the preplantar. From this a
well-defined groove runs horizontally backwards to the notch which is
found in the wing between the basilar and retrossal processes. Along
this groove the preplantar division of the digital artery runs. A series of
foramina are also arranged in a kind of semicircle disposed horizontally a
short distance from the inferior border. Through these the ascending
group of vessels derived from the arterial arch termed the semilunar
anastomosis, emerge.
The Superior Surface.—This is the least extensive of the surfaces
of this bone. It is distinguished from the two remaining surfaces, also,
by the fact that it is entirely articular. In the middle line it presents a
slight ridge, which is disposed antero-posteriorly. In the articulated joint
it is accommodated in the shallow antero-posterior groove, already
described, on the inferior surface of the second phalanx. The convexities
on the last-mentioned bone are received into two shallow depressions,
which are placed one on either side the above-mentioned ridge.
At the back of this surface there is a transversely-elongated narrow
facet, which is almost flat, and which articulates with a similar facet found
on the anterior portion of the inferior border of the navicular bone.
Anteriorly the surface passes upwards on the back of the pyramidal
process to terminate near the summit.
The Inferior Surface.—This is divided into two areas by a curved
roughened ridge called the semilunar crest. The part in front of the
crest is termed the solar or plantar area. In outline it is somewhat
crescentic, and is concave or vaulted. It responds to the sensitive sole.
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Plate XII.—Wall of Abdomen removed, showing Intestines.
i. Prominence caused by sternum. 2. End of xiphoid cartilage. 3. Diaphragmatic flexure of
large colon. 4. Supra-sternal flexure. 5. Apex of caecum.
         6. First part of large colon.
7. Second part of ditto. 8. Body of caecum. 9. Floating colon. 10 and 11. Small intestine.
To face page 7JO.
-ocr page 33-
PARTS WITHIN THE HOOF
l2
Behind the semilunar crest is the tendinous or semilunar area. This
area shows on either side a large circular foramen, to which a deep oblique
groove runs from the notch in the wing of the bone. Along the groove
the plantar division of the digital artery runs, and passes through the
foramen (which also receives the name plantar) into the semilunar sinus
—a cavity in the interior of the bone.
The Antero-Superior Border.—This border is raised in the middle line
into an upwardly projecting piece of bone called the pyramidal process.
This is convex anteriorly, and roughened for the attachment of the tendon
01 insertion of the extensor pedis muscle. Its posterior surface is smooth
and articular, and is continuous with the articular surface of the bone.
On either side the process is an elongated, narrow depression, the floor of
which is roughened. In this pit the antero-lateral ligament of the
corono-pedal joint is attached. Behind the depression there is an elevated
piece of bone which is compressed laterally, and both faces of which are
rough. This is the basilar process. A deep notch is placed posteriorly
to the basilar process. This is the notch to which the preplantar groove
conducts, and in very old animals it is frequently converted into a complete
foramen. At the posterior limit of the bone, and separated from the
basilar process by the notch just mentioned, we have another process
which projects backwards. This is called the retrossal process, and it
is placed at a lower level than the basilar process. These two processes
enter into the formation of the wing of the bone, and they afford attach-
ment to the lateral cartilage. The basilar and retrossal processes were so
named by Bouley and Bracy Clark respectively.
The Postero-Superior Border is almost straight, and passes horizontally
across the bone between the inner surfaces of the two wings. It forms
the posterior limit of the elongated facet, already described, for articulation
with the navicular bone.
The Inferior Border.—This is thin and sharp, and it separates the
anterior or laminal surface from the plantar area of the inferior surface. It
is somewhat irregularly serrated, and in outline it approximates to the
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Plate XIII.—Seat of Operation in Laparo-Enterotomy.
Skin. 2. Fibres of external oblique muscle of abdomen cut across. 3. Incision in internal oblique muscle of abdomen along- the direction
of the fibres. 4. Incision in transversalis abdominis. 5. Loop of intestine exposed. 6. Direction of secondary incision for drainage.
To face page 134..
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i4          THE SURGICAL ANATOMY OF THE HORSE
greater portion of the circumference of a circle. This is more particularly
so in the terminal phalanx of the fore limb. In the hind limb the bone
is not so distinctly rounded at the toe; the edge terminates posteriorly at
the extremities of the retrossal processes.
The Navicular Bone
This is frequently termed the small sesamoid bone. It is placed at the
back of the corono-pedal articulation, and is commonly referred to as
being shuttle-shaped.
For the purposes of description, this small bone may be said to possess
two surfaces, two edges, and two extremities.
The surfaces are anterior or superior and posterior or inferior. The
anterior or superior surface is directed upwards and forwards. It is
smooth and entirely articular, and presents two shallow depressions
separated by a broad ridge, the latter being disposed antero-posteriorly.
The posterior or inferior surface looks downwards and backwards. It is
the more extensive of the two surfaces, and, like that already described,
it possesses two depressions separated by a ridge. The depressions are
more shallow, however, and the intervening ridge much narrower.
Although this surface is quite smooth, it is not articular, and in the
recent state is clothed by fibro-cartilage for the play over it of the tendon
of the deep flexor of the digit, which passes over the surface of this bone
to its insertion into the semilunar crest of the pedal bone.
The superior border is traversed lengthways by a deep furrow, the
floor of which is roughened for ligamentous attachment and is perforated
by numerous small foramina which transmit vessels into the interior of the
bone.
The inferior border presents anteriorly a narrow, elongated, almost flat
facet, which runs horizontally almost the whole length of the border, and
which is articulated to the similar facet, already described, at the back of
the superior surface of the terminal phalanx. For the remainder of its
extent this surface is depressed and roughened for the attachment of
-ocr page 36-
PLATEr^iy-"7^E PKLV1C- lNPT lN TH? MARE' showinS how its outline differs from that of the
i MiddWlntStf'T" ,S '"I6" thr°Ugh l5e 1Umbar re&ion funher foa^ than in P?a7e XI )
i. Middle gluteus muscle. 2. Longissimus dorsi. 3. Sub-lumbar muscles 4 Rectum 7 RiVht
Uterine cornu with suspended ovary. 6. Interior of pelvic cavity. 7 Body of ulerus 8 Parieta
peritoneum (this is preserved almost intact in the area exposed/so that details iiJ dissection are not
exposed as in Plate XI.) 9. Fundus of bladder.
To face page 144..
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PARTS WITHIN THE HOOF                            15
the interosseous ligament which unites the navicular and pedal
bones.
The bone tapers down at its extremities, and the latter are roughened
and afford attachment to the postero-lateral ligaments of the corono-
pedal joint.
The navicular bone ossifies from a single centre.
The Second Interphalangeal Joint
The bones entering into the formation of this joint are the distal
extremity of the second phalanx, the navicular bone, and the upper end
0 the pedal bone. It is frequently called the coffin joint and corono-
pedal articulation.
The navicular bone is united to the pedal bone in such manner as to
fender its superior or articular surface continuous with the articular
surface of the pedal bone. The surfaces of both bones together form
a curyed area which presents a median antero-posterior ridge, and on
either side of this a shallow depression, the ridge and depressions being
r°ken only at tne line of
apposition of the two bones. In this depressed
tne interior surface of the second phalanx is accommodated, and
ace, it will be remembered, presents two convexities separated by
a shallow antero-posterior groove.
e Ligaments of the joint are as follows:
" interosseous Ligament.—This forms a powerful bond of union
-en the navicular and pedal bones. It consists of short but strong
osseous fibres which run from the non-articular area which is placed
tne racet on the inferior border of the navicular bone, and which
icned inferiorly to the pedal bone just below the posterior margin
icular surface. Some fibres are also inserted into the posterior
ot the tendinous area of this bone.
• ^ n ero-Lateral Ligaments.—There are two of these ligaments, one
•r side. They are attached superiorly to the depressions found on
ateral aspects of the inferior extremity of the second phalanx, from
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Plate XV.—A.—Seat of Urethrotomy.
i. Anus. 2. Retractor penis muscle (the muscle has been drawn aside by hook). 3. Skin and subcutaneous fascia.
4. Accelerator urinoa muscle. 5. Wall of Urethra. 6. Interior of Urethra.
B.—Transverse section of Tail showing principal Vessels and Nerves.
1. Skin.         2. 3. 4. 8. 9. 10. Coccygeal muscles.         5 and 6. Superior and inferior lateral coccygeal arteries,
with their accompanying veins and nerves.        n. Middle coccygeal artery.
To face page 164.
-ocr page 39-
I
16          THE SURGICAL ANATOMY OF THE HORSE
whence the most anterior fibres take a course which is downwards and
forwards, and become inserted in the depressions which are placed one on
either side the pyramidal process of the pedal bone. The central fibres
run almost vertically downwards to the pit, whilst the most posterior
incline slightly backwards. It is a broad ligament, its breadth being
greatest at its insertion into the pedal bone. Many of its fibres appear to
blend posteriorly with the corresponding lateral cartilage, and anteriorly
with the expanded insertion of the tendon of the extensor pedis.
3. Postero-Lateral Ligaments.—There is also one of these ligaments
on either side. In reality it is the downward continuation of some of the
fibres of the corresponding lateral ligament of the first interphalangeal
joint. After leaving the os coronae the fibres form a cord. The major
portion of the ligament is attached inferiorly to the extremity and upper
border of the navicular bone, where its fibres meet those of the corre-
sponding ligament of the opposite side. A short bundle of fibres also
passes to be inserted into the deep face of the lateral cartilage, whilst
still another is attached to the retrossal process of its side.
The Synovial Membrane.—Anteriorly the synovial membrane lines the
deep face of the tendon of the extensor pedis muscle. There is no
anterior common ligament, and in consequence the tendon mentioned
closes in the front of the articulation. At the side it is supported
anteriorly by the deep face of the antero-lateral ligament, and posteriorly
by the corresponding surface of the postero-lateral. It throws out a
small diverticulum on either side between the two lateral ligaments.
This is the pouch which has already been referred to as being liable to be
opened when operating in the treatment of quittor, and its presence
should be carefully noted. In addition to the main articulation, the
synovial membrane also supplies the small arthrodial joint formed between
the navicular and pedal bones.
It will be remembered that the inferior articular surface of the second
phalanx encroaches to a considerable extent on the posterior surface of
the bone. To supply this portion of the articulation, the membrane
-ocr page 40-
Plate XVI.—Coverings of Left Testicle Incised.
2. Dartos. 3. Cremasteric layer. 4 and 5. Layers of fascia. 6. Tunica vaginalis.
7- Left testicle.
I. Skin.
To face page 172.
1
-ocr page 41-
PARTS WITHIN THE HOOF                           17
sends upwards at the back of the joint an extensive pouch which runs
upwards to the slip which passes from the tendon of the deep flexor of
the digit to the back of the os coronas, where it is in close relationship
with both the navicular bursa and the inferior cul-de-sac of the sesamoid
bursa.
This joint is an imperfect member of the ginglymoid or hinge
variety, and its principal movements are, therefore, flexion and extension.
The small articulation between the navicular and pedal bones is a simple
arthrodial joint in which slight gliding movements only are possible.
Over the front of the joint the tendon of the extensor pedis muscle
plays. It is here spread out in a sheet-like manner, and blends on either
side with the corresponding division of the superior sesamoidean ligament.
It passes to its insertion into the pyramidal process of the terminal
phalanx.
The tendon of the deep flexor of the digit passes over the back of the
joint. It runs over the postero-inferior surface of the navicular bone,
and then downwards and forwards, to become inserted into the semi-
lunar crest of the pedal bone and a small roughened area behind the
crest.
The nerves of the foot were described in Part II.
THE BLOOD-VESSELS OF THE FOOT
The Arteries
The foot is supplied by the digital arteries. In Part II. these vessels
were followed to the inner aspect of the lateral cartilages, where each
divided into the corresponding plantar and pre-plantar arteries.
The Preplantar Artery passes through the notch which separates the
basilar and retrossal processes, and then runs forwards along the groove
which bears the same name. During its course it gives off the following
branches:
c
-ocr page 42-
B
d
V \
—16
2
3------------
I
bis
4.-
— 14
5—
a
7-------------
2
—12
b
11
9---------
c
-10
Plate XVII.
2. Tail of epididymis. 3.
7. Edge of scrotal incision.
A.—Left Testicle withdrawn from Scrotum.
Body of epididymis. 4. Tunica vaginalis. 5. Vas deferens. 6. Incised edge of
8. Right testicle in scrotum. 9. Spermatic artery and plexus of veins exposed by
phe. II. Prepuce. 12. Preputial orifice. 13. Head of epididymis.
I. Body of testicle
tunica vaginalis.
slitting tunica vaginalis.
B.—Transverse section across left
Inguinal Canal (sbmischematic).
1. Obliquus abdominis internus muscle. 2. Spermatic artery. 3. One of spermatic veins. 4. Tunica vaginalis 5. Inguinal nerve.
6. Interior of inguinal canal. 7. Sac of tunica vaginalis. 8. Vas deferens. 9- External pudic vein
         10. External pudic artery
11. Cremaster (external). 12. Inguinal nerve.
13. Cremaster (internal). 14. Tunica vaginalis. 15. Spermatic nerves. 16. Ldge
of Poupart's ligament.
a anterior boundary, b posterior boundary, c inner angle, d outer angle.
-ocr page 43-
i8          THE SURGICAL ANATOMY OF THE HORSE
r. Before passing through the notch referred to, a small branch is
detached which passes in a retrograde manner to the bulb of the heel.
2. After leaving the notch the following branches are given off:
(a)   A branch which passes backwards in a retrograde manner.
(b)   Numerous ascending and descending branches which are distributed
to the lamina?. The former anastomose freely with branches which
descend from the coronary circle and the circumflex artery of the coronary
cushion. The descending branches anastomose with the terminal
ramifications of the ascending branches of the plantar arch.
The Plantar Artery.—This is much the larger of the two divisions of
the digital artery. It runs along the plantar groove, passes through the
plantar foramen, and enters the semilunar sinus, where by its inosculation
with the corresponding vessel from the opposite side the plantar arch or
semilunar anastomosis is formed. This arch is thus within the pedal bone.
From the arch two sets of branches emanate—namely, an ascending set,
which escape by the foramina on the laminal aspect of the pedal bone,
and which contract anastomoses with branches of the preplantar artery,
as indicated; and a descending set, which consist of much larger vessels.
These pass out through the foramina near the inferior border of the bone.
Each of these vessels anastomoses with those on its right and left in such
manner as to form an arterial arch, which is placed on the inferior aspect
of the terminal phalanx and follows the line of its inferior border. This
arch was named by Chauveau the circumflex artery of the foot, and is
not infrequently called the circumflex artery of the toe, and care must
be taken not to injure it when paring the sole here. From this circum-
flex artery a number of branches are given off which are distributed to
the tissues of the sole.
The Veins
The veins of the foot have an extraordinary arrangement, and are
grouped into intra-osseous and extra-osseous systems.
The presence of an intra-osseous system of veins was not recognized
-ocr page 44-
■Jp
-'.
w
Tit
A
Plate XVIII.—Testicles in situ.
i. Entrance to sheath. 2. Median raphe. 3. Position of right testicle.
A. Testicle grasped, scrotal integument made tense ready for incision.
To face page iyb.
-ocr page 45-
THE BLOOD-VESSELS OF THE FOOT                  19
by the older anatomists, but it is now generally conceded that the ascend-
ing and descending arterial branches of the plantar arch are accompanied
by satellite veins. These discharge their contents into a semicircular
venous arch placed within the semilunar sinus. Blood from this arch
is drained by two veins, which pass out one on either side by the plantar
foramina. The veins then run alongside the plantar arteries in the
plantar grooves, and each concurs in the formation of the corresponding
venous plexus, which is found on the deep face of the lateral cartilage.
The extra-osseous system is usually described in three parts—namely,
the solar or plantar, podophyllous, and coronary plexuses, and these form
an intricate but complete meshwork for the foot.
The vessels of the Solar Plexus ramify in the fibrous structure known
as the plantar reticulum, which takes the place of periosteum on the
inferior surface of the pedal bone. Blood from this network passes either
into veins which converge towards the centre of the digit to join what
is known as the central canal, or into vessels which join the circumflex or
peripheral vein. The central vein embraces the point of the pyramidal
body, and its contents are discharged by two veins, which leave one on
either side to pass along the corresponding lateral lacuna and join the
external coronary plexus. The circumflex or peripheral vein is the
satellite of the circumflex artery of the toe, along the concave border of
which it runs. In addition to the veins from the solar plexus already
described, it receives all the descending veins from the podophyllous
plexus. Posteriorly on either side the circumflex vein terminates by
splitting into a number of vessels which contribute to the formation of
the superficial coronary plexus.
The Podophyllous Plexus is held in the meshes of a fibrous reticulum,
named by Bracy Clark the reticulum processigerum, which takes the
place of periosteum on the laminal surface of the terminal phalanx. They
run in a wavy manner in the direction of the lamina;, and they com-
municate freely with each other. Superiorly they communicate with the
veins which form the coronary plexus, whilst they join below the
-ocr page 46-
Plate XIX.—Portion of Ilium and Walls of Pelvic and Abdominal Cavities removed, showing Rectum, Vagina, Uterus,
Bladder and Right Ovary.
i. Anus. 2. Vulva. 3. WTall of vagina. 4. Cotyloid cavity. 5. Lateral border of sacrum. 6. Bladder (distended). 7. Body of uterus.
8. Uterine artery. 9. Rectum. 10. Uterine broad ligament. 11. Inferior ilio-sacral ligament. 12. Right uterine cornu. 13. Angle of croup.
14. Right ovary. 15. Ilium sawn through. 16. Last rib. 17. Right kidney.
N.B.—Owing to the removal of the other viscera, the ovary and horn of the uterus hang down to a lower level than ordinarily ; when the animal is
not pregnant they are pressed upwards near the roof of the cavity and the ovary^is placed behind the kidney (17).
To face page 206.
-ocr page 47-
ao          THE SURGICAL ANATOMY OF THE HORSE
circumflex vein in the manner already indicated. There is little, if any,
direct communication between the veins of the solar and podophyllous
plexuses and those of the intra-osseus system.
The Coronary Plexus is described in three portions—namely, a central
part and two lateral divisions.
The central part forms a very close network which lies beneath the
coronary cushion. The vessels which enter into its formation are
continuations of the ascending veins of the podophyllous plexus, and in
turn the veins of this central portion discharge their contents superiorly
into a large vessel which passes round the front of the limb in a semi-
circular manner, and which places the cartilaginous plexuses in com-
munication. From the manner in which they join, the veins of the
central portion of the coronary plexus decrease in number, but increase in
size, as they ascend, so that opening into the semicircular vessel described
there are usually only from ten to twelve apertures.
'The Lateral or Cartilaginous Parts.—Each lateral part consists of two
layers, one on each face of the corresponding lateral cartilage. On the
superficial face of the cartilage there is a very dense network of vessels.
These, as they ascend, join in such manner as to form ten to twelve veins,
and these in turn unite, until there are ultimately formed two veins of
considerable size, which by their union near the inferior end of the os
suffraginis form the digital vein, the course of which has already been
described. On the deep face of the cartilage another network of vessels
is placed, and this receives the vessel which drains the blood from the
intra-osseous system of veins, as already mentioned. It also receives
ascending veins from the posterior part of the plantar and podophyllous
plexuses, and the deep veins which drain the blood from the region of the
os coronae and the tendons and ligaments of the part. The two layers of
the cartilaginous plexus communicate freely by small vessels which pass
through the canaliculi by which the cartilage is pierced.
It is of great importance to note exactly the position of the small
articulation between the navicular and pedal bones in relation to the
-ocr page 48-
.. Rectum 2WTi of                      " °* ^'^ ^^ P°SIT10N 0F 0s "««.
N.B.-H wTbe obsem^ thatThe o f • f" 4 ^^ «^. 5- Distended bladder.
observed that the os uter, ,s almost on a level with the centre of the cotyloid cavity
To face page
2og.
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OVER-REACH—TREAD OR TRAMP                    21
inferior surface of the foot. In deciding this, a reference to the Plate
representing a longitudinal mesial section of the foot will be found
helpful. An open arthritis of the joint is a common complication of
punctured foot, gathered nail, etc., and it will be readily understood that
the most serious position in which a nail can be gathered is in line with
this articulation.
INJURIES TO THE FOOT
OVER-REACH—TREAD OR TRAMP
An over-reach is an injury to a fore foot inflicted by the shoe of a
hind foot. The term tramp or tread is sometimes restricted to a
bruise of the coronet inflicted by the shoe of the opposite foot. It may
occur in the fore or hind foot, and is frequently found in cart-horses as a
result of an injury inflicted when endeavouring to start a heavy load or
when backing or turning it. Such injuries are, of course, on the inner
side of the foot; but external injuries may be inflicted by the other horse
of a pair. In over-reach the injury is usually caused by the sharp
posterior border of the web of the anterior portion of the shoe. The
injury is usually an irregular wound at or just above the heels, and from
our description of the anatomy of the part it will be readily understood
that there will be a considerable amount of haemorrhage. The condition
is easily noticed. In the case of a tread, the seat of injury may not at
first be apparent. The animal goes lame, and the lameness becomes
progressively more pronounced. The animal is apparently in great pain,
and may even show systemic disturbances in an elevation of temperature
and anorexia.
It is obvious that, in animals which have a tendency to over-reach,
injury may be avoided by suitable shoeing of the corresponding hind foot.
Frequently short shoeing behind is sufficient. At other times a concave
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Plate XXI.—Ovariotomy.
Operator's arm in position to grasp ovary. The hand is passed up the vagina and then through the incision above the os uteri. In a pony
14 hands high the distance of this incision from the entrance to the vul/a was 7'$"-
To face page 212.
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22          THE SURGICAL ANATOMY OF THE HORSE
shoe [i.e., a shoe with the sharp edge, which usually inflicts the injury,
removed) is applied — quite a rational method of prevention. Over-
reaching boots are sometimes put on fore feet for protection. If an
injury has been inflicted, the part should be washed with disinfectants,
dusted over with dry dressing, and then bandaged.
A tread is a much more serious affection. If the case be seen early,
the object must be to endeavour to prevent necrosis and sloughing. This
is done by scarification. The affected area is punctured in two or three
places, and the foot is placed in hot water to encourage bleeding. The
part is then dressed with antiseptics and a bandage applied.
An examination of the coronet may at first reveal nothing. Later
the part becomes moist and extremely tender to the touch. It will be
noticed that the hair now stands erect, and a close examination will reveal
the fact that a more or less circular area of tissue is being marked' off
from the rest. Later this circumscribed area sloughs away.
The depth of tissue which sloughs and the subsequent course of the
affection depend upon the severity of the injury. Frequently the removal
of the slough leaves a simple superficial wound. At times the injury is
so severe that, when the part has sloughed, even an open joint with a
copious discharge of synovia may result.
If the case is not seen until the affected area is circumscribed by a
well-defined line of demarcation, early separation of the necrosed tissue
should be encouraged by applying hot poultices or fomentations to the
coronet. These are discontinued after the part has sloughed, and the
ordinary treatment adopted to encourage the wound which remains to
heal from the bottom by granulation. During the treatment febrifuges
should be administered internally.
To prevent the appearance of secondary necrosed areas, it is advisable
to draw a line around the affected area with the actual cautery, or to
paint around it with tincture of iodine.
A common complication of a severe tread is the formation of a quittor,
which is dealt with elsewhere. The usual treatment should be adopted
-ocr page 52-
Plate XXII.—Female Genital Organs.
I. Left horn of uterus. 2. Right horn slit open shewing interior. 3. Fimbriated end of left fallopian
tube. 4. Right fallopian tube. 5. Left ovary. 6. Broad ligament. 7. Ovarian artery. 8. Body of
uterus. 9. Uterine vein. 10. Branch of internal pudic artery. II. Uterine artery. 12. Os uteri.
13. Branch to internal pudic vein. 14. Interior of vagina. 15. External opening of urethra.
16. Interior of vulva. 17. Clitoris. 18. Right lip of vulva.
N.B.—A layer of the left broad ligament has been dissected away to display the vessels. The ligament
has also been slit to display the fallopian tube.
To face page 222.
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VILLITIS                                               23
when a joint is opened as a result of sloughing. If the extensor tendon
be exposed, any ragged parts should be immediately removed, otherwise
necrosis of the tendon may follow.
VILLITIS
This is the term applied by Haycock to inflammation of the coronary
band. Simple inflammation of this structure is frequently observed to be
associated with other diseases of the foot, such, for instance, as quittoi
and sandcrack. Septic villitis is usually a sequel to simple inflammation
of the part, and is due to the introduction of micro-organisms. When
this occurs, the part becomes swollen, and frequently the hair falls out.
The swelling increases in size until the part begins to overhang the hoof,
and does so in some cases to the extent of three or four inches. The
surface is very sensitive to the touch, and in places ulcerated. Later,
separation takes place between the coronet and the hoof, followed by the
formation of multiple abscesses, which burst, discharge their contents,
and heal up, only for other abscesses to appear elsewhere. There is
much systemic disturbance, and the animal is evidently in great pain.
If placed in slings, the foot is held off the ground. Poultices are some-
times applied, but they only aggravate the case ; and since treatment is of
little avail, it is best to have the animal destroyed.
HORN TUMOURS
Horny growths are sometimes found at the coronet and the sole.
The growth is called a keratoma. The growths at the coronet are usually
due to some injury to the coronary band. The actual cause of similar
growths on the sole is more difficult to determine. They push out the
sole and form a rounded elevation. No apparent symptoms may be
presented for some considerable time, and attention to them is usually
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24           THE SURGICAL ANATOMY OF THE HORSE
drawn in the first instance by the farrier. Whilst preparing the foot for
the reception of a shoe, the edge of the knife is arrested by a hard, dense
substance through which the knife will not pass. When cleansed it
presents a glistening appearance, and if the surrounding horn be removed,
it will, as Macqueen states, be found to be attached by a short stem or
pedicle to the sensitive sole. Macqueen's treatment is to free the growth
from the surrounding horn, and then sever the pedicle as near as possible
to the pedal bone, care being taken to remove as little as possible of the
sensitive membrane. The haemorrhage which inevitably occurs is arrested
by plugging the wound with tow saturated with antiseptic. The part
is then dusted with dry dressing and a leather sole applied.
A keratoma under the wall is frequently called a keratophyllocele or
keraphyllocele. This is an elongated growth, and sometimes extends
along the whole depth of the wall from the coronet to the margin
separating the wall and sole. Injury to the coronary band causing inflam-
mation leads to a hypersecretion of horn substance from the band, and the
tumour is said to be simply an aggregation of the horny laminae so
produced. As would be naturally expected, the growth as it develops
exerts pressure on the underlying sensitive structures, and from the pain
which this produces the animal is the subject of chronic lameness. In
time it may even destroy the sensitive lamina?. The pedal bone is fre-
quently the subject of pressure atrophy, and presents a longitudinal groove
which extends from just below the pyramidal process to the inferior edge
of the bone.
In cases where the horn is not too resistant, we have an external
indication of the presence of the underlying growth in the form of a
narrow ridge extending down the anterior surface of the wall; and should
the horn be abnormally brittle, it is not infrequently fissured along the
line of direction of the tumour. The laminae on either side the growth
are closely applied to it, and some may even be confounded with the
tumour.
Diagnosis is somewhat difficult in most cases. The animal is lame,
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HORN TUMOURS
25
and at first there may be nothing, apparently, to account for it. Percussion
frequently brings no response. According to Macqueen, when the con-
dition affects the fore foot, there is a suggestive tilting of the toe during
progression.
If the shoe be removed and the foot carefully examined, an area near
the toe will be found to be softer than the surrounding horn. It is readily
differentiated from a case of seedy toe, since there is no space present.
On exploration of this area, an abnormal growth will be found which
extends upwards, and diagnosis may be completed by removing a portion
of the adjacent wall.
The treatment consists in excising the growth, and the best method
of operation is that recommended by Macqueen, which is as follows :
The ordinary shoe is removed, and one is applied possessing two
lateral clips instead of a toe-clip. The wall between these two clips is
rasped well down, and then the animal is cast. Attention is now directed
to the upper portion of this area, first the wall being cut on either side.
The underlying growth is then dissected away with the segment of the
wall, particular care being taken when working near the coronary band.
If this part of the operation has been successful, the lower portion of the
growth will frequently detach itself. Careful and deliberate dissection is
necessary if successful results are to be achieved and the recurrence of the
growth prevented.
The subsequent treatment is to dress the part with antiseptics and
then bandage.
SEEDY TOE
Cases are frequently encountered where the wall at the toe is separated
into two layers which are of unequal thickness, the deeper layer being
usually much the thinner. The area between the two layers is usually
filled by " soft mealy horn," but in some cases there is an actual space
between them.
To this condition the term seedy toe is applied. The degree of
D
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26          THE SURGICAL ANATOMY OF THE HORSE
separation in the wall varies, and it may extend from the edge separating
the wall and sole right up to the coronary band. Its breadth also varies,
and it may include the whole of the area designated as the toe, extending
on either side to the quarter.
The presence of lameness depends to a great extent upon the thickness
of the deeper of the two layers into which the wall has become separated.
Occasionally this is so thin as to permit of the passage of extravasated
blood through it when pressure is placed on the foot during progression,
and in these cases the animal is lame. In those cases where there is little
difference between the thickness of the two layers, the action of the
animal is not affected.
Little is known regarding the cause of the affection. It has been
attributed to an injury caused by the toe-clip. Cases have been recorded
as having been preceded by laminitis, but, as Macqueen suggests, the
symptoms and history suggest that the disease is probably constitutional,
due to the production of defective intertubular material in cases where the
length of the wall is not kept within reasonable limits.
Fortunately the condition is one which yields readily to treatment.
The shoe should be removed, and all the loose powdery horn scraped out
of the cavity, which is then thoroughly cleansed. The cavity is next
plugged with cotton-wool or tow saturated with some antiseptic. Pro-
viding the animal is not lame, it should continue to work, rest being
unnecessary. If the affection caused lameness, the above treatment should
be followed by the application of a blister to the coronet, to stimulate a
better growth of horn.
Some operators remove the more external of the two layers, open up
the cavity throughout its extent, scrape its sides and floor, and then treat
with antiseptics.
Subsequent shoeing should depend upon the case. Pressure on the
diseased area should be relieved either by making a depression on the
bearing surface of the shoe, or by excising a portion at the inferior edge
of the wall. If the latter method be adopted, the foot remains disfigured
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FALSE QUARTER                                       27
for a period of from six to eight months—i.e., until the renewal of the
wall is complete. The toe-clip should be dispensed with and two lateral
clips applied.
In cases where there is exudation of blood through the deeper layer
of the wall, unless treated immediately, the cavity gradually becomes filled
with granulation tissue. In such cases the external layer of the wall
should be removed and the part cauterized. Dry astringent dressings are
then applied and pressure bandages. Should the case be complicated by
the presence of ulceration, successful treatment is more difficult, and the
action of the patient is usually affected.
Occasionally similar conditions affect other parts of the wall—e.g., the
quarters. To these the name " loose wall" is sometimes given. The
nature and treatment are similar to those described above.
FALSE QUARTER
Injuries in which the coronary band is implicated, such as treads,
quittors, some cases of over-reach, etc., frequently result in a destruction of
horn-secreting tissue, with the result that a perfect wall is no longer
secreted, but the portion of the wall immediately beneath the seat of the
injury is much thinner and weaker than the adjacent portions. The thin
and weak area may be about two inches in breadth, and may extend from
the coronary band to the inferior margin of the wall. The condition is
known as a false quarter. It may occur in fore or hind feet, and is usually
seen on the inner side. The defect, however, is not confined to the
quarter. It may be in front of or behind it. Lameness as a result is
not common; but since the condition is not amenable to treatment, and
the wall is weak, it should be regarded as an unsoundness.
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28           THE SURGICAL ANATOMY OF THE HORSE
SANDCRACK
This is the common term applied to a fissure of the hoof. The most
common situations are the toe and quarters, the former being most fre-
quently encountered in hind feet, and the latter in fore. In rare cases
similar fissures may be found on the sole and bars. The direction taken
is usually in the line of direction of the horn fibres. Quarter sandcracks
sometimes take an oblique direction, and the edges of the crack overlap,
so that careful examination is necessary to ascertain its depth.
Sandcracks are classified as " complete " when they extend the whole
length of the wall, and " commencing " when they only extend for a
short distance down the wall from the coronary band. It is interesting
to note that most sandcracks commence at the upper edge of the horn
tissue, and their length increases with the growth of the wall.
False sandcracks or fractured wall are fissures which are placed near
the inferior margin, due to excessively brittle horn or to neglect in shoeing.
They are comparatively simple both as regards their nature and treatment.
They cause little inconvenience to the animal, and, from what we have
said regarding the anatomy of the part, it will be understood that the
tendency will be for them to disappear with the growth of the hoof.
Sandcracks may be recent or old-standing, and it is a matter of
importance to differentiate between them. If old, they are confined to
the superficial structures, and the animal is not lame. In such cases, also,
the edges of the crack are usually irregular and more or less scaly.
Recent cracks are most serious if they are deep and extend beneath the
coronary band, when they invariably cause severe lameness. Frequently
there is haemorrhage from the fissure, when the condition is complicated
by injury to the underlying sensitive laminae.
In countries which are susceptible to extreme climatic variations, the
condition is common during the dry weather following a prolonged rainy
period. The cracks usually appear suddenly ; those at the quarter develop
slowly.
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SANDCRACK
29
Macqueen states that, whilst many are due to defective secretion of
horn, the exciting cause in many, if not all, cases is concussion.
Faulty shoeing, such as excessive rasping of the wall, or using shoes
which are too heavy or nails which are too thick, may also be a contribu-
tory cause. There may be a hereditary predisposition in a natural
weakness of the wall.
Whilst sandcracks can frequently be detected without difficulty, in
many cases a careful search has to be made for them. They are often
obscured by dirt or hoof dressing. Occasionally they are wedged. In
rare cases they extend from within outwards, and these cases when com-
mencing are practically impossible to diagnose with certainty.
From what we have said it will be gathered that the degree of
lameness varies. It may be entirely absent, or the animal may be so
lame as to be absolutely unfit for work. In the latter case the whole
thickness of the wall is usually penetrated, and the sensitive underlying
structures damaged by foreign material which has gained access through
the fissure. Lameness is due to irritation by foreign material so intro-
duced rather than to movement of the edges of the broken wall, as
frequently supposed. Sandcracks at the toe are usually regarded as being
more painful than those at the quarter. In obscure cases gentle per-
cussion will frequently prove helpful in diagnosis, and in some cases of
commencing sandcrack, where nothing can be seen on the exterior, careful
palpation will reveal a slight depression in the coronary band, indicating
the position of a fissure at the upper extremity of the wall.
In addition to haemorrhage, other affections which may follow as
complications of sandcracks are suppuration, necrosis, quittor, tetanus,
keratoma, and septic infection.
Suppuration is associated with marked systemic disturbance. The
temperature rises, the animal declines its food and wastes rapidly.
Owing to the great number of varieties of sandcrack, it is difficult to
form a definite prognosis. Simple cracks near the inferior border rarely
cause trouble, and the animal may also continue to work with fissures
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30          THE SURGICAL ANATOMY OF THE HORSE
near the coronet, providing they are superficial and do not penetrate the
whole thickness of the wall. A guarded prognosis should always be
given if the crack causes lameness, and another point to be remembered
is the great tendency which a sandcrack has to recur.
Should there be no lameness, the shoe should be taken off and the
position of the clips altered according to the situation of the fissure. If
the latter be at the toe, quarter clips are used. In all cases the bearing
should be eased under the seat of the crack.
There are various methods of preventing an extension of the crack,
such as filling it up with hoof substitute, clinching the edges, binding the
hoof with twine, etc.
In all cases the subsequent blistering of the portion of the coronet
immediately above the crack will promote the growth of a better quality
of horn. It is advisable, also, to dress the hoof periodically with hoof
ointment or some other such dressing which will prevent excessive
evaporation from the horn.
In cases where the sandcrack is large, with thick walls, but which
does not cause much lameness, the walls may be clamped or the hoof
fired. There are several different methods of clamping. Sometimes
special clamps are used, of which there are numerous varieties. A
notable one is McGilPs. But the parts may be clamped very effectively
with a slightly curved ordinary shoeing nail.
There are also various methods of firing the hoof. Some operators
fire two oblique lines, one on either side the crack, and meeting
below it. Others draw two parallel lines, one on either side the crack,
and extending down the wall for about one-third its length. Still
another method is to fire parallel transverse lines across the crack at
intervals of an inch to an inch and a quarter. The lines should not
penetrate the whole thickness of the wall, and should only extend
through the white hoof tissue. Subsequently the coronet should be
blistered.
If the animal is not lame, movement may be prevented in the part by
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SANDCRACK
31
wedging the crack. For this purpose some operators use a piece of hard
wood, others whalebone owing to its greater elasticity. The wedge is
driven into the crack from below upwards, and its surface is then reduced
to the level of that of the surrounding wall by means of a fine rasp.
If lameness be very pronounced, and the animal holds its foot off the
ground and shows other evidences of great pain, the shoe should be
removed and the foot carefully examined. The wall surrounding the crack
should be rasped and the edges of the latter thinned down. The foot
should then be placed into hot water or a hot poultice be applied. Hot
poultices will generally soften the part and prepare it for further treatment
next day. The crack should then be opened up, because in such cases
there is invariably inflammation of the underlying sensitive laminas, due to
the presence of foreign material beneath the hoof. If the crack extends
down to the toe, a portion of the wall on either side sufficient to permit the
escape of any purulent material which has accumulated should be removed.
The foot is then placed into medicated baths or poultices for two or three
days. If the animal should continue to hold the foot from the ground, it
should be examined again, and a little more of the wall removed with the
rasp. The cavity may also be injected with a weak solution of carbolic
acid. Rapid improvement should be exhibited if the treatment is going
to terminate ouccessfully. A shoe with the bearing eased at the seat and
with two lateral clips should be applied as soon as weight can be borne by
the foot.
When suppurating, the crack should be well opened up and the area
disinfected.
After the acute symptoms have subsided, there is frequently developed
a quantity of granulation tissue which may form to an excessive degree
and project through the fissure. This may be reduced by the application
of astringent dressings, followed by pressure bandaging over rolls of cotton
wool or tow laid on the granulating surface.
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32            THE SURGICAL ANATOMY OF THE HORSE
CORNS
A corn is defined by Macqueen as a bruise of the sensitive sole
between the bar and the wall, and usually on the inner side of the foot.
The fore feet are most commonly affected, but corns are not infrequently
encountered in hind feet.
There are several different kinds, but all may be placed in one of three
classes—namely :
i. Simple or dry corns, in which there is very little lameness, and from
which the animal is usually said to " go short." They are of a chronic
nature.
2.   Moist corns, in which the bruise has resulted in a serous exudate
being poured into the deeper layer of horn, which becomes softened.
Commonly these are discovered by the farrier when preparing the foot,
for on removal of the superficial layer of hoof an area is encountered which
is softer than the surrounding horn.
3.   Suppurating corns, when pus-producing organisms gain access to the
bruised area.
The bruise may be inflicted by a loose stone or pebble. Frequently it
is caused by the extremity of the branch of a shoe which has been left on
for too lengthy a period, and which has become displaced; or the bruise
may be due to applying shoes with branches which are too short, or with
heels which are too thick and interfere with the functions of the frog, so
that the heels become ultimately narrowed.
At first attention might be drawn to the animal's pawing its bedding
and being otherwise restless in the stable. When ridden or driven, it is
found that there is a loss of freedom of action, and the steps are shorter.
Some cases may be readily mistaken for navicular disease. If the area
suppurates, there may be swelling of the coronet towards the posterior
part of the foot.
In the treatment of corns it is advisable to study each individual case.
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CORNS
33
There are several different methods of prevention, such as the application
of a Charlier shoe or a flat shoe fitted carefully at the heels. A leather
sole is also frequently utilized, but one of the best methods of prevention
is to remove the shoe frequently to prevent the extremity of the branch
sinking into the heel.
With regard to curative treatment, at times a simple case can be
treated, with satisfactory results, by reshoeing with a bar shoe relieved at
the seat of corn, and it may not be necessary to rest the animal. Other
cases of simple corn, where the action is short and confined, are treated by
removing the shoe and paring the seat of the corn to relieve pressure.
The foot is then placed into hot water or hot poultices at intervals for a
few days, when the animal is reshod with an ordinary open shoe or a bar
shoe relieved at the seat of corn.
Moist corns should be poulticed for two or three days; and if the
animal is still lame, a little tincture of iodine or of a 5 per cent, solution
of carbolic acid should be applied. A suitable shoe is then placed on the
foot, but in no case should the animal be reshod until he goes fairly free
from lameness.
If the presence of pus be suspected, the part should be explored
carefully, and to give free exit to the pus a portion of the horny sole
should be removed. It may be necessary, also, to remove a small portion
of the bar, but it is always advisable to spare the bar as much as possible.
Having thus opened up the seat, it should be thoroughly disinfected and
dressed daily until the discharge of pus has ceased, when the shoe may
be replaced. Cases of suppurating corn demand immediate and careful
treatment, since neglected cases commonly lead to the formation of a
quittor.
When the bruise occurs at some part of the sole other than the seat
of corn, the term bruised sole is applied to the injury. The condition is
very similar to a corn, and is generally caused by loose stones. The
animal is very restless, and at times holds its foot up. Frequently nothing
can be seen, and the seat of injury is only discovered when the superficial
E
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34          THE SURGICAL ANATOMY OF THE HORSE
layer of horn is scraped away. Percussion will reveal evidence of pain.
The sole should be thinned over the affected area, to which a compress
is applied and kept in position for two or three days by means of a
bandage. When the animal is reshod, a pad of tow or cotton-wool should
be placed on the sole and the part protected by leather.
The degree of injury from such bruises varies considerably. In some
cases even the terminal phalanx may be damaged. In all cases the injuied
part should be exposed, to avoid any risk of accumulation of purulent
matter beneath the sole. Should there be any necrosis of bone, the
diseased portion should be removed with the curette.
Similarly, we may have bruised frog when the condition affects the
frog, or bruised heel when the bulb of the heel is affected.
STRIPPING THE SOLE
There need be no hesitation in removing the sole if it is considered
necessary for effective drainage, for a thin covering of protective horn is
formed in from twenty-four to thirty hours, and in from seven to eight
days a fairly good sole is formed. An artificial protection to the stripped
part is therefore necessary only for a short time. The sole is best removed
piecemeal. Its removal will be greatly facilitated if the horn be first
softened by placing the foot into hot water or poultices.
The portion to be removed should first be marked out with a French
hoof knife ; a groove should now be made almost through the thickness
of the sole, extending from the wall to the point of the frog. It should
then be carried backwards along the lateral border of the frog. Commenc-
ing again at the anterior limit of the area to be stripped, another groove is
made backwards along the junction of the sole and wall. When this
groove meets the one which passed backwards along the side of the frog,
the whole area will be encircled. Two or three grooves should now be
drawn along the intervening piece of sole, radiating from the inner
boundary to the outer.
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GATHERED NAIL
35
Separation between the sole and wall should now be completed, and
one of the pieces between the grooves picked up at its anterior end and
removed by stripping backwards. If the case is one in which the
removal of the sole is necessary, the stripping may be performed without
much difficulty and without giving much pain, owing to the fact that the
pus which has accumulated beneath the sole brings about a separation
between it and the underlying structures.
GATHERED NAIL
This is the term commonly applied to an injury to the foot due to
puncture by a nail which has been picked up whilst at work. The injury
is usually caused by nails with flat expanded heads, such as American box
nails or slater's nails.
With regard to the severity of the injury, much depends upon the
condition of the nail and the position of the puncture. A clean galvanized
nail is much less likely to produce serious effects than one which is rusty.
The position and depth of the puncture are of the greatest importance in
offering a prognosis. A reference to the longitudinal sagittal section
of a foot (Pla'-e VI.) will reveal the fact that there is a fairly extensive
area which may be punctured without very serious results apart from the
chipping of a small portion of the pedal bone. On the other hand, it will
be apparent that a puncture in the region of the middle third of the frog
may be attended by most disastrous results, for above this area lie the
perforans tendon with its sheath, and the joint formed between the navicular
and pedal bones. Fatal results of punctures in this area are common.
The navicular bone may be fractured. When suppuration follows in such
cases, they are usually hopeless.
The animal is lame. If the nail is in position or has been extracted
by the carter, who brings it with him, diagnosis is of course easy.
Frequently, however, a careful search has to be made to discover the seat
of puncture. In most cases it may be seen without difficulty after the
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36          THE SURGICAL ANATOMY OF THE HORSE
removal of the superficial layer of horn. To ascertain the depth of the
puncture and the direction which it takes, it should be carefully probed,
the foot being held firmly. Punctures of the sole usually present little
difficulty. The foot should be washed, the hoof surrounding the puncture
thinned, the parts dressed with antiseptics and then bandaged. Next day
the bandage should be removed and the part examined. If still discharg-
ing, the puncture should be opened up and searched. Some powerful
disinfectant, such as pure carbolic acid, is now applied, a plug is inserted
into the opening, and the part again bandaged. This dressing should be
repeated from time to time until the discharge ceases. Should the dis-
charge still continue and present a dirty watery appearance, injury to the
pedal bone should be suspected. An exploration with the probe will
generally confirm this, for it will now impinge upon a rough surface. In
such a case the animal should be cast, more of the sole removed, and the
pedal bone exposed and scraped. Any fractured piece should be removed.
The subsequent treatment is that for an ordinary wound.
Punctures at the bulbs or point of the frog are treated similarly, but
it has already been stated that punctures at the sides or cleft of the frog
are much more serious. The area around the puncture should be thinned
down and the part compressed. Should blood exude, it is a favourable
symptom. If the discharge presents a black or muddy appearance, the
opening should be enlarged, and some undiluted antiseptic, such as carbolic
acid or perchloride of iron, injected, the foot being then bandaged. If
lameness subsides a little after two or three days, the progress is favourable.
Frequently in such cases, however, lameness becomes accentuated, the
animal limps badly and at times holds its foot from the ground, refuses
to lie down, sweats, and is the subject of anorexia. Such symptoms
are serious.
Many cases of gathered nail yield after four or five injections. It is,
however, a condition in which patient treatment is required. Should the
discharge cease after injections, it is a favourable symptom, although the
animal might still be lame. With a prolonged period of rest the case
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NAIL BOUND, NAIL PUNCTURE, AND DRAWN NAIL 37
will frequently recover; most cases require a period of three months' rest
during convalescence.
In some cases the perforans tendon is lacerated, and the navicular bone
may be damaged or even fractured. Suppuration usually occurs in such
cases, and treatment is rarely of much avail. The joint becomes fixed,
and even after most careful treatment the animal remains more or less
lame.
NAIL BOUND, NAIL PUNCTURE, AND DRAWN NAIL
Nail binding is a condition due to close or faulty nailing, in which
the nails are driven sufficiently near to the sensitive membrane to exert
undue pressure upon it. The membrane, however, is not pierced. It
may be due to the position of the nail holes of the shoe being too close
to the inner border of the web, or the holes may incline too much
upwards and inwards. Carelessly-driven nails also frequently cause it,
and it is common in animals in which the wall of the hoof is abnormally
thin. When the sensitive membrane is pierced, the term nail puncture is
applied, whilst the term drawn nail is given to those conditions when the
nail has been driven either too close to or into the sensitive structures,
and has subsequently been removed.
Occasionally the condition is purely the result of an accident, and is
not due to any fault on the part of the farrier—such, for instance, as
when the hoof is defective, as stated above, or when the horse is
particularly unruly.
The condition will be easily understood if a reference be made to the
Plate representing a longitudinal mesial section of the foot.
The degree of lameness varies. At first the animal may be only
slightly lame, or may show no symptoms of lameness at all for two or
three days. In other cases lameness is most severe, and the animal when
standing holds its foot (when the one affected is a hind foot) two or
three inches off the ground.
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          THE SURGICAL ANATOMY OF THE HORSE
The foot should be carefully examined, and by gently tapping the
wall with the hammer over the line of direction of each nail the particular
seat of injury may generally be ascertained.
The treatment consists in withdrawing the nail, if still in position,
and removing the shoe. When the nail has been in position for two or
three days, the discharge which appears after its withdrawal presents a
dirty watery appearance. In cases of more recent puncture the discharge
is blood-tinged. Occasionally a purulent discharge exudes. The particular
nail hole should be opened up and injected with antiseptic solutions.
When there is no discharge, the case is usually one of nail binding only.
In cases of binding, the foot should be placed in hot water to soften
the parts and relieve the pain.
When the shoe is replaced, the nail should be omitted from the
affected hole.
LAMINITIS
This is the term applied to inflammation of the lamina? and the other
vascular tissues of the foot. In those acute cases, however, where the
keratogenous membrane is mainly involved, the only portion (according to
Macqueen) which is not inflamed is that covering the bulbs of the plantar
cushion.
Macqueen describes three degrees—namely, chronic, subacute, and
acute. The chronic form is very common, and the patient can perform
light work. All kinds of horses are, apparently, affected by it. The
fore feet are usually attacked; sometimes the hind, and in rare cases all
four, feet are affected. It not infrequently happens that lameness in the
fore feet occurs after the hind feet have been affected with laminitis for
two or three days.
At times complete recovery from an acute attack takes place in less
than a fortnight, and no traces of the disease are left. But frequently the
acute form becomes chronic, and the animal remains affected for months
or even years. Occasionally a horse suffering from chronic laminitis
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LAMINITIS
39
suddenly presents symptoms of the acute form. This change frequently
occurs during an attack of influenza, purpura hemorrhagica, or strangles.
The actual cause of laminitis has not been definitely determined, but
the tendency to-day is to regard it as of micro-organismal origin. It is
not included in the list of hereditary diseases by the Horse Breeding
Commission, but Macqueen considers that horses born of laminitic
parents are more likely to contract the disease than those whose parents
have sound feet.
Amongst the contributory causes which are generally accepted in this
country are overfeeding, overexertion, concussion, sudden changes of
temperature after hard work, rapid driving over rough ground, etc. It
frequently follows difficult parturition, and is not uncommonly a sequel
to inflammation of the lungs, pleura, or bowels. Travelling stallions are
often affected. Although the above are associated with the disease as a
result of clinical observation, it will readily be conceded that our know-
ledge of its causation is by no means definite, and ultimately it may be
found, as Macqueen states, that these conditions have little, if anything,
to do with the actual cause.
An animal suffering from acute laminitis seen early is usually found
in the standing position. The surface of the body is cold and the
muscles twkch. The systemic disturbance is very marked. The
temperature rises three or four degrees, respirations are accelerated, and
the mucous membranes injected. The pulse is usually full and strong.
If seen after five or six hours, the animal is generally found standing
with head erect and showing no inclination to move. The surface of
the body is hot, and sweating is profuse. The temperature is still further
elevated; the feet are hot, and the plantar arteries frequently present a
peculiar throbbing. If forced to move forwards, the steps are very short,
and after proceeding for a short distance the muscles above the elbow and
stifle twitch. The patient is evidently in great pain. When the fore feet
only are affected, they are projected forwards and rest on the heels; the
hind feet are brought well forwards under the body to support the weight.
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40          THE SURGICAL ANATOMY OF THE HORSE
Light tapping of the hoof will cause the animal to flinch. If the hind
feet only are affected, the fore feet are drawn well back under the body
to take the weight, the hind feet being drawn forwards on the heels.
When all four feet suffer, the position may be similar to that described
in average cases of anterior affection, or the four feet are spread out after
the manner adopted in micturition. There are also presented in these
cases peculiar jerky, convulsive movements of the limbs.
The congestion of the laminae is followed by exudation, and the
exudate softens and severs the connection between the horny and sensitive
laminae. After a few days, unless resolution occurs, the pedal bone
rotates on its transverse axis and becomes displaced, and in front of it we
have either a space or an increased amount of fibrous tissue. The coronet
becomes much enlarged and the wall thickens; in some cases a new wall
forms beneath the old one. In most cases of displacement of the pedal
bone we have bulging of the sole. Another deformity is the appearance
of laminitic rings or grooves around the wall; they are distinguished from
other hoof rings by the fact that they are not continuous, but are broken
and frequently run into one another. The horny and sensitive laminae at
the toe frequently increase in thickness, as also does the wall, but the
bulged sole usually becomes very thin.
Suppuration of the foot may occur as a complication ; the animal
now becomes very restless and paws continuously, the temperature rises
and the pulse quickens. Another complication occasionally encountered
is necrosis of the laminae, whilst in some cases we have septic infection of
the limbs, which swell rapidly, when the patient usually dies. We are
still without a satisfactory explanation of some of the changes which
occur in the foot in an ordinary case—such, for instance, as the appearance
of the laminitic rings and the thinness of the sole. An imperfect secretion
of horn will account for the brittleness of the hoof.
There has been much discussion as to the cause of the dropping of the
sole and descent of the pedal bone. The most reasonable explanation
appears to be that it is due to pressure by the inflammatory exudate which
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LAMINITIS
4i
has been poured between the bone and the resistant wall. In support
of this it has been stated that, in those cases in which the wall is unusually
thin and gives under pressure of the exudate, the pedal bone does not
descend, but we have an anterior bulging of the wall.
Prognosis in the early stages should be guarded. The case should
show improvement before the end of the second day if a favourable
termination is to be expected, and if at the end of the fourth day there is
no marked improvement, it may, with a fair amount of confidence, be
decided that the disease will assume the chronic form. Cases of slight
depression of the pedal bone should not be condemned, as a run out to
grass will frequently effect considerable improvement, particularly in light
animals.
It is generally more economical to destroy at once cases in which the
pedal bone projects through the sole, or where suppuration or necrosis is
present as a complication.
From what we have said, it will be gathered that cases seen early
require systemic treatment. It is usual to administer a full dose of
purgative unless the affection be itself a complication of some condition
in which purgatives are contra-indicated. Some febrifuge (e.g., quinine)
should also be given. Arecolin is regarded by many as highly effective in
the treatment of this disease.
Opinions have differed widely regarding the local treatment to be
adopted. The view was commonly held that the shoe and sole assisted in
preventing the descent of the pedal bone. From what has been stated
regarding this complication, it will be readily deduced that neither the
shoe nor the sole can have any effect upon it. As Macqueen states, the
whole of the sole may be removed and the bone yet remain in position.
The treatment recommended by Macqueen is to remove the shoe at once,
even though it be necessary to put the animal down. The foot is pared
and all loose horn removed. The wall is then lowered slightly and the
foot placed in hot water or poultice. Poultices have no curative effect,
but they form a soft tread, and this should always be provided. Heavy
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THE SURGICAL ANATOMY OF THE HORSE
bodied horses should be put down to relieve the pressure on the feet.
The side of the box is well bedded up. The fore foot is taken up with
a sideline. The animal is caused to slide gradually on to the floor by
applying pressure on its broadside.
In the early stages of pus formation, the pus should be liberated at
once by opening the sole. The operation is performed an inch in front of
the point of the frog and slightly to the right or left of the middle line,
when the subsequent treatment is similar to that of an ordinary abscess.
Opinions have long differed as to the efficacy of bleeding for the relief of
congestion in laminitis. W. Williams considered " local bleeding from the
coronary plexus advantageous, relieving the congestion and alleviating
pain." Macqueen states that animals may be bled if the disease be in its
early stages, and that the blood should be drawn in preference from the
jugular vein. He condemns bleeding at the toe on the ground that wounds
of feet affected with laminitis heal very slowly.
If progress be favourable, poultices are discarded after three or four
days, when the feet may be reshod. There are several kinds of
shoes which are utilized. A kind which has obtained a considerable
degree of notoriety is that introduced by Broad of Bath, who believed in
early exercise, to which W. Williams took exception. Broad's shoe
was thick at the quarters and thin at the toe and heels, and favoured
the natural rocking movement of the foot. Others adopt an open shoe
with thin heels. There appears to be little doubt but that progression is
facilitated during certain stages of the disease by the application of a
rocker-bar shoe which " follows the lead which Nature gives." When
the animal is able to walk with ease, the hair should be removed from the
coronet and a blister applied. This is followed by turning out to grass or
into a loose-box with short litter.
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PUMICE FOOT
43
PUMICE FOOT
Macqueen applies the term pumice foot to that chronic condition of
the fore feet which generally follows laminitis. In it the sole is either
flat or convex, is very thin, and gives on pressure. The foot is deformed,
the cutigeral groove abnormally wide, and the toe is rounded. The horn
is usually of defective quality. It is unusually brittle, is easily broken and
reduced to powder. There is no curative treatment, but it will be obvious
that such feet require special shoeing. The best type of shoe is the
quoit. This approaches the elliptical in outline, the lesser circumference
being the more prominent; and thus, although it has a wide web for the
protection of the sole, the weight is thrown upon the wall. The nail
holes are numerous (usually about twelve), and these are punched
where the soundest horn is placed, the shoe being then attached with a
leather sole.
THRUSH
This is the term applied to a common affection of the frog in which
a discharge usually appears at the cleft. If neglected, however, the
disease spreads to the rest of the organ, and we may have a discharge
appearing at the lateral lacunas. The discharge has an offensive odour
which is somewhat characteristic.
Thrush is an affection of uncertain cause, but is frequently associated
with defective hygienic conditions of the floor of the stable, and by some
with certain types of litter bedding.
W. Williams attributed it to " a diseased condition of the secreting
surface of the fibro-fatty frog." In a normal foot the cleft of the frog
is extremely shallow. A well-marked cleft is usually indicative of
previous treatment with the knife. This removal of horn is probably
a contributory factor.
Thrush rarely causes inconvenience apart from the offensive odour of
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44          THE SURGICAL ANATOMY OF THE HORSE
the discharge. Unlike canker, with which it was at one time associated,
it is readily amenable to treatment.
The part should be washed and disinfected. Macqueen recommends
the application of poultices containing common salt, followed by calomel,
copper sulphate, iron sulphate, burnt alum, iodoform, zinc oxide, etc.
Attention should be directed to the bedding and to the cleanliness
of the stable.
CANKER
This is the name which, since olden times, has been applied to a
chronic affection of the foot of the horse. It usually commences at the
frog, from which it extends very gradually to the sole, bars and wall,
beneath which it may reach as far as the coronet. It is characterized by
hypertrophy of the villi of the sensitive membrane and the production
of an exudate with a very offensive odour. The commencing stages
are often overlooked, and attention is frequently drawn to the case in
the first instance by the farrier, whose knife encounters a small area of
horn tissue which is abnormally soft. On removing this, it is found to
be underrun by the peculiar exudate referred to. As the condition
advances, the frog becomes greatly enlarged and deformed.
It is still a debatable point as to whether canker should be placed in
the category of surgical or medical diseases. Early writers regarded the
condition as cancerous. Many still believe it to be constitutional. The
late W. Williams stated that " it usually commences in the frog . . . but
it is not a rare thing to see it commencing in any other part of the
plantar surface, or of the laminated structure of the wall, excited by a
wound, prick, or other injury." M oiler and Dollar claim that the disease
" is probably due to specific infection . . . but the infection does not
appear to be due to a single organism, but to several, which do not always
agree in their method of action." We have had such organisms associated
with the disease by Megnin, Jowett, and others. Holmes has recently
treated with marked success advanced cases of canker, and also cases of
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CANKER                                               45
thrush, sandcrack, and brittle hoof, by the internal administration of
arsenic, and states that it is " possible that arsenic may have a direct
action on the still unknown causal organism."* The subject of causation,
however, remains to a considerable degree in obscurity, and further
reference to it would only be a resume of research work or clinical
observation without definite results.
Heavy cart-horses are the type commonly affected. The disease is
frequently confined to one foot, but all four may be affected. It always
runs a chronic course, and in the earlier stages rarely causes lameness.
To achieve successful results, a prolonged course of treatment is necessary.
In offering a prognosis, it should be remembered that the best results are
obtained in young vigorous animals, and in those cases in which only a
restricted area is affected and the spread of the disease is slow. A sudden
rapid spread is most unfavourable, but such cases are rare. The owner
must be instructed not to expect a quick recovery.
Treatment consists in the removal of the fcetid cheese-like material,
the destruction of the hypertrophied villi, and the subsequent application
of dressings of astringents and disinfectants. All horn which is underrun
should be removed with the knife, and the material beneath it scraped
away. Some operators destroy the overgrown tissue by applying the
actual cautery. Others apply nitrate of silver, chloride of zinc, formalin,
sulphate of zinc, iron, lead, etc., carbolic acid, etc. The late W. Williams
had great faith in the efficacy of chromic acid. Malcolm's well-known
dressing consists of equal parts of sulphates of copper, iron, and zinc,
mixed with strong carbolic acid and a little vaseline. But notwith-
standing the fact that all these have their adherents, there is, as Moller
states, no specific local application for canker. Malcolm showed that
canker, though an extremely troublesome disease, was in most cases
remediable provided the treatment be persistent. After removing
the cankered tissue and cauterizing the diseased are,a, the dressing
* J. D. E. Holmes, "Internal Administration of Arsenic in Canker," Veterinary Journal, vol.
kix., No. 456, pp. 259-262.
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46          THE SURGICAL ANATOMY OF THE HORSE
is applied on tow or cotton-wool, and kept in position by affixing the
shoe with an iron plate or leather sole which will keep the dressing in
apposition with the diseased surface and also apply pressure to the part.
An even distribution of pressure can be secured by working up the tow or
cotton-wool into rolls, as recommended by Pillers. It is frequently
unnecessary that the animal should cease to work—in fact, the majority
of cases are said to do better if kept at work. The same process should
be repeated daily ; much more depends upon the care and persistency of
the operator in dealing with the diseased areas than upon any one
particular drug, In fact, it is frequently of advantage to the case to
utilize a different dressing every two or three days. As the case
progresses, it should be dressed every two days, then twice a week, and
lastly once weekly until recovery is complete. If the actual cautery be
used daily in the earlier stage of treatment, it must be used sparingly and
with little pressure; otherwise there is a danger, after several days' applica-
tion, of exposing and damaging the pedal bone.
QUITTOR
Frequently as a sequel to a tread or tramp, a badly-driven nail, a
sandcrack, a corn, or some other injury to the foot, followed by the
formation of pus, the latter is discharged through an opening at the
coronet, usually over the area of the lateral cartilage. To this condition
the term quittor is applied. The condition is thus very similar to an
abscess which bursts. The discharge usually appears at the coronet, a
little above the junction of the skin and hoof, the coronet having
previously been swollen and the animal lame.
The pus is thus in close proximity to the lateral cartilage, and necrosis
of the cartilage as a result is generally the cause of the persistence of the
discharge in all cases of quittor, for all are chronic. Occasionally the
pressure of the pus leads to necrosis of some of the sensitive lamina?.
It is usual for quittor to be confined to one side of the foot, and for
one cartilage, therefore, to be affected. Sometimes the pus accumulates
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QUITTOR                                               47
on the superficial aspect of the cartilage, which is softened by its action.
In other cases, necrosis or ulceration occurs near the junction of the
cartilage and the wing of the pedal bone, and here a number of arches
may be formed. The cartilage may be perforated and the pus collect on
both surfaces. The most superficial cases, and also the most hopeful, are
those in which the posterior curved portion of the cartilage is affected.
The abscess cavity may contain a piece of necrosed cartilage which has
become detached from the main portion, or there may be present a piece
of the pedal bone or a necrosed portion of the keratogenous membrane.
One of the most important of the factors which contribute towards the
slow healing after the abscess has burst is the absence of facility for good
and adequate drainage.
The most simple cases are those placed just above the bulb of the
heel. These are usually commencing cases, for, as already stated, ulcera-
tion and necrosis of the cartilage generally proceed from behind forwards.
The abscess cavity is small, and a probe, if introduced, readily passes to
the sole at the heel, where a dependent opening is easily made which
permits of adequate and effective drainage. The pus in these cases is
accumulated between the bulb of the plantar cushion and the wall at the
heels, and the cavity so opened up can be readily injected out from
above downwards.
When the condition extends farther forwards, treatment varies. In
all cases where the lateral cartilage is involved the foot must be opened
up. Various other methods have been adopted. Thus, for instance,
treatment by injection is very common, for which purpose Villate's
solution has a wide reputation. The sinus is injected out several times
a day; a single injection daily is regarded as useless. It is stated that the
injection of Villate's solution or corrosive sublimate creates "a harmless
chemical slough." Injections frequently arrest the process of ulceration
of the cartilage and diminish the quantity of the discharge; but the
improvement is deceptive, for it is usually temporary, and a complete
cure is rare.
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48          THE SURGICAL ANATOMY OF THE HORSE
Another method, which is sometimes described as " coring out the
quittor," is to introduce caustic powders or pencils.
The actual cautery by means of the pointed firing iron is sometimes
applied with successful results, for the introduction of the iron into the
depths of the sinus destroys the diseased parts, and a healthy reaction is
promoted in the tissues which remain.
The surgical method is to remove a portion of the wall of the hoof.
The animal is cast and placed under a general anaesthetic. The depth
and direction of the sinus are ascertained by careful probing, and the wall
over the sinus is thinned by means of the rasp until it springs under
pressure with the thumb. With the ordinary hoof knife two oblique
grooves are made in the wall; they meet inferiorly and enclose an area
in the form of the letter V. The apex of the V-shaped piece of horn is
then raised by means of a stout probe and seized with the pincers, by
means of which it may be stripped from below upwards. Precaution is
taken not to remove any more of the coronary band than is absolutely
necessary. Immediately beneath the wall there will be exposed either a
portion of the lateral cartilage or keratogenous membrane, depending
upon the situation. Any visible portion of cartilage should be carefully
examined. Sound and healthy cartilage presents a shiny appearance;
diseased cartilage is of a dirty greenish colour and is much softer to the
touch. Diseased portions of cartilage or keratogenous membrane must
be removed, and the walls of the sinus curetted. The coronary band can
be dissected free from the underlying structures, so that it may be raised to
search for and remove any purulent matter found beneath it. By means
of careful probing, it should be ascertained that the actual depth of the
sinus has been reached. It occasionally happens that, having arrived at
what was its apparent extremity, it is found to take a sudden deviation
at an angle forwards or backwards. This necessitates the removal of an
additional portion of the wall. Some operators strip a rectangular portion
of the wall. By careful dissection it is possible to remove the whole of
the lateral cartilage without severing the coronary band. A plentiful
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QUITTOR
49
application of dry dressing follows the washing out of the part with some
antiseptic, such as a 5 per cent, solution of carbolic acid. The area is
then covered with tow or cotton-wool, and the foot bandaged fairly
tightly. The bandage is allowed to remain in position for two or three
days, when it is removed and the part examined. Should there be still
some suppuration, a careful examination should be made for diseased
tissue, which should be removed and the part dressed as before. If the
case does well, the wound will heal by granulation from the bottom.
The greatest care must be taken when the sinus is placed well forward
near the edge of the tendon of the extensor pedis. When operating here,
there is a danger of producing an open arthritis of the coffin joint as
a serious complication by penetrating the cul-de-sac of the synovial
membrane, which is here placed, and to which attention has already been
directed. When such complication arises, a swelling appears behind the
pastern, and the abscess breaks out at the bottom of the heel. Treatment
in such cases is practically hopeless, hence the extreme care necessary to
be taken to avoid any injury to the membrane. If for some reason the
coronary band is cut whilst removing the cartilage, its severed ends should
be sutured when the flap of skin is replaced.
A good and effective method of bandaging a foot in cases of quittor is
to utilize a long, narrow, stout tape. A long nail is driven into the toe,
and its free end curved downwards. The tape is passed round the heel
and under the hook-like end of the nail, and wound tightly in such
manner that the whole of the affected area is covered. By this means an
even pressure can be produced, and the bandage does not cover the bearing
surface of the foot.
Bayer's operation for the excision of the whole or part of a lateral
cartilage, is as follows:
The horn covering the seat of operation is thinned and the area
dressed with disinfectants the day before the operation. The animal is
cast, placed under an anaesthetic, and a tourniquet applied to the affected
limb. A crescentic piece of horn is then removed from the area of the
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50           THE SURGICAL ANATOMY OF THE HORSE
cartilage. About a quarter of an inch within the boundary of the area
exposed, another crescentic incision is made, this time through the
sensitive layer and parallel to the first incision made through the horn.
The arms of this second incision are carried upwards through the coronary
band and the skin as far as the upper limits of the cartilage. The U-shaped
flap of tissue is then dissected upwards and the underlying cartilage
exposed. The whole or portion of the cartilage, as found necessary, is
then removed, and the walls of the sinus scraped with the curette. All
diseased tissue is carefully removed, and any large vessels accidentally
severed are to be ligatured. The part is then dusted over with dry dress-
ing, and the flap which was reflected upwards is replaced and fixed in
position by inserting a number of simple interrupted sutures. The whole
area of operation is then sprinkled with dry dressing and the part carefully
bandaged, care being taken to distribute the pressure equally over the
area to prevent corrugation of the flap. Should no serious complication
arise, the bandage is allowed to remain in position for from ten to twelve
days.
After operating for quittor, the accumulation of excessive granulation
tissue at the coronet, which so frequently presents an objectionable
eyesore, should be restricted by the application of astringent dressings.
SIDEBONE
This is the term applied to ossification of the lateral cartilage.
Attention has already been directed to the importance of being able to
map out accurately the outline of a cartilage, and to manipulate it in order
to ascertain the degree of rigidity which it possesses.
Occasionally the cartilage becomes replaced by bone in light horses,
but the condition is usually encountered in heavy draught animals. The
cartilages most commonly affected are those of the fore limbs, but side-
bones are occasionally encountered in the hind limbs. The Royal
College of Veterinary Surgeons, when appealed to, decided that the
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SIDEBONE
51
affection should be regarded as hereditary, presumably on the ground that
there was transmitted to the progeny from the sire and dam a " peculiar
defect of conformation or quality of structure wrhich predisposed to
ossification." Animals regarded as being most predisposed to the affection
are those with big limbs, thick heels, upright blocky feet, and short
pasterns. Macqueen claims that the change in the cartilage, which is
mostly hyaline, seems to be more or less a natural one ; that all cartilages
tend to ossify with age, and that probably ossification in this case is
hastened by defective shoeing.
The change in the cartilage may occur as the result of a blow, or
during prolonged treatment for some other affection, such as quittor,
sandcrack, etc.
There is scarcely a defect which is regarded with graver suspicion by
laymen. Yet a simple study of the anatomy of the part will enable one
to deduce that, as a serious affection calculated to interfere materially with
the utility of the animal, sidebone is very much over-estimated. This
fallacious view is probably due to the frequency with which sidebone
is associated with the presence of ringbone—a disease often much
more difficult to diagnose, and consequently likely to escape the attention
of the untrained observer. From the nature, position, and relations, of
the cartilage, it will be seen that the substitution of bone can only entail
a loss of elasticity in the part, and restrict slightly (in narrow blocky feet)
the lateral expansion of the plantar cushion. That this should cause
lameness appears to be very " far-fetched," and, notwithstanding the
popular antipathy to the affection, one is inclined to agree with Macqueen,
who states that it is " doubtful if uncomplicated sidebone ever causes
lameness," and with the late W. Williams, who claimed that sidebone in the
hind limb " is very rare, and, so far as I know, never occasions lameness."
Many different methods of treatment have been from time to time
adopted. Williams recommended the application of a " bar " shoe ; rest,
firing, and blistering, and, failing these, neurectomy. A long bar shoe is
claimed to improve the action, which is necessarily somewhat " cramped."
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THE SURGICAL ANATOMY OF THE HORSE
52
Smith's operation, which is only indicated in sidebone complicated
by contraction, to permit of the expansion of the wall, consists in
grooving the wall beneath the sidebone with a specially-designed saw.
The first groove passes vertically downwards from the anterior limit of
the sidebone, and extends the whole length of the wall to the inferior
margin. Another groove is made posteriorly, slightly in front of the
posterior margin of the wall, before it curves round to become continued
as the bar. This groove runs obliquely downwards and forwards. A
third groove is placed midway between these, and inclines slightly
downwards and forwards. The grooves should pass through the whole
thickness of the wall.
FRACTURE OF THE NAVICULAR BONE
The navicular bone is deeply seated, and placed in such manner as to
be particularly well protected against risk of external injury. Outwardly
we have the adequate protection afforded by the wings of the pedal bone.
Posteriorly it is clothed by the expanded tendon of the flexor perforans.
Anteriorly are the second and third phalanges ; whilst inferiorly are the
plantar cushion and the frog. Notwithstanding this protection, fracture
of this bone sometimes occurs as a result of a nail gathered near the cleft
of the frog. Fracture sometimes follows navicular disease, particularly
that form in which the bone is weakened by being hollowed out. In
these cases the fracture results from pressure by the tendon of the flexor
perforans. It is said also to be a complication of neurectomy. The bone
is found on post-mortem to be not infrequently fractured in colliery ponies,
when the foot has been run over, or crushed by a heavy fall of roof.
At times it is found to be fractured without there having been any
history of previous disease or accident.
The condition is difficult to diagnose. To ease the pressure of the
flexor tendon on the damaged bone, the foot is held with the toe directed
backwards. There are evidences of intense pain when the corono-
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NAVICULAR DISEASE                                    53
pedal joint is forcibly extended. Later there is a filling up of the hollow
of the heel.
Prognosis is most unfavourable, as even partial recovery is rare.
NAVICULAR DISEASE
This is one of the most serious diseases with which the surgeon is called
upon to deal. Attention was first directed to it by two Englishmen—
Turner and Coleman. Before their time the condition was regarded as
being an affection of the cofEn joint, and was generally described as
coffin-joint disease. It is now sometimes termed navicular arthritis.
It is a disease in which there is usually evidence of a chronic inflam-
matory process in the navicular bone itself, in the fibro-cartilage covering its
posterior surface, and in the tendon and tendon sheath (or navicular bursa).
Since the discovery of the disease, opinions have differed as to the
structure in which it actually originates. Some say it commences in
the bone and extends to the sheath. Others claim that the reverse is
the case. But, as Macqueen points out, the examination of a number of
specimens will lend support to both these views, for at times the bone
presents very little, if any, external evidence of disease. Yet its interior
may be hollowed out and its weight appreciably reduced. On the other
hand, the cartilage may present evidence of disease in a number of erosed
areas, whilst the bone remains apparently healthy. Occasionally a tiny
hole is present on the ridge on the posterior surface of the bone ; a com-
mencing necrosis of the bone and necrosis of this ridge is by many
regarded as the earliest stage in the disease process. Inflammation of the
fibro-cartilage is supposed to follow, leading to ulceration. The fibro-
cartilage thus becomes removed, leaving a roughened surface. During
the movements of the parts, the synovial apparatus and the tendon become
irritated and diseased.
Many and various are the opinions which have been expressed
regarding the cause of navicular disease. Peters and Williams con-
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54          THE SURGICAL ANATOMY OF THE HORSE
sidered that one of the principal factors which contributed to the
development of the disease was an upright fetlock, and the disease is
generally associated with some hereditary predisposition. Many old writers
attributed the disease to a narrow hoof, maintaining that the arched sole
exerted undue pressure upon the navicular bone. Brauel claimed that
this view was erroneous, and was based upon mistaken diagnoses, in that
cases of contracted sole were regarded as navicular disease. Macqueen
claims that concussion as a result of hard and constant work is the
principal responsible agent. The writer has frequently had the oppor-
tunity of observing the course of this disease in Welsh cobs, and has
found it to be common amongst tradesmen's horses driven by boys. In
animals which are thick-set and heavy in front, and in which the angle
formed between the long axis of the large metacarpal bone and an
imaginary line drawn through the long axes of the first and second
phalanges (see Plate VIII., Vol. II.) is unusually obtuse, the greater will
be the proportion of the concussion sustained by the limb, which is
thrown upon the posterior portion of the arc formed by the articular
surfaces of the pedal and navicular bones. To this extent, then, the
disease may be considered to be hereditary. But with reference to what
might be regarded as the exciting cause in the type of animal referred to,
the writer is impelled to the conclusion that it is abnormal concussion.
The quick rate at which the animal is driven, the short distances
involving quick starting and sudden stoppages—these in an animal of
fiery temperament, and particularly in those which are handled in such
manner as to diminish elasticity in the movements of the limb and to
cultivate a quick, snappy action of the muscles, cause the foot to be placed
on the ground with abnormal force, and the limb to be subjected to an
unusual amount of jar. This in the type of conformation mentioned is at
least in part borne by the navicular bone.
Although it has been observed in hind feet, such cases are extremely
rare, and the disease may be almost said to be confined to the fore limbs.
It is sometimes said to appear in early life, but the usual history is
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NAVICULAR DISEASE
55
undoubtedly that it manifests itself very gradually, and only after the
animal has been at work for three or four years.
The first sign is that the animal gradually loses action, a change
which is only noticeable to the accustomed driver. There is no lame-
ness, neither is there any change which would attract the attention of
the casual observer. The driver finds that, particularly when starting,
the animal does not step out with its accustomed freedom. For some
months there may be nothing further to report, until the animal begins
to become uneasy. He paws the floor frequently when in the stable,
and occasionally "points" the foot. At this stage he shows a little stiffness
when first brought out, but this quickly passes off with exercise. There
is yet no lameness. After a further period the steps become shorter
and the action is " pottery." The shoe is worn at the toe, and the
pastern becomes more upright. Slight lameness is now apparent on
starting, but it disappears after the animal has gone a short distance,
and this intermittent lameness may show itself for many months. In
many cases the shape of the foot becomes altered. It becomes more
blocky, and is deeper and narrower posteriorly. It was formerly held
that navicular disease only affected upright blocky feet with deep and
narrow heels. It is now generally conceded that the best feet might
become affected. On the other hand, horses with " mule " or blocky
feet frequently work well throughout life without presenting any signs
of navicular disease. The pointing of the foot is not a constant symptom.
In the majority of cases lameness either disappears or becomes considerably
diminished with exercise. A peculiarity of the lameness, as Macqueen
points out, is that its degree varies according to the condition of the
atmosphere. It is most apparent in hot dry weather, and diminishes in
wet weather. The " peculiar stilty stiffness," which is best manifested
in the early morning, is now commonly regarded as the best diagnostic
symptom. When the disease is in an advanced stage, the limbs are fully
extended and the feet pushed out on rising, in a manner somewhat
resembling the attitude during an attack of laminitis.
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56          THE SURGICAL ANATOMY OF THE HORSE
When the animal " points " the foot, the distance to which it may be
advanced varies considerably. At times it may be only an inch or two in
front of the other foot. At other times it is advanced for nine or ten
inches. But irrespective of the distance to which it is advanced in
navicular disease, the foot rests flat on the ground. In many other affec-
tions, when the foot is advanced, it rests on the toe.
The size of the frog diminishes, and it becomes carried up out of
function, the sole becoming increasingly concave.
It is important, in forming a diagnosis, to remember that animals are
not usually affected before they are five years old, and most commonly
they are over six, and the history is that they have done a considerable
amount of hard work.
It is evident that the injection of cocaine over the course of the
internal and external plantar nerves, whilst enabling the observer to decide
that the case is one of foot lameness, will, not provide conclusive evidence
of navicular disease.
Increased pressure on the frog, and through the medium of this on the
seat of the disease, will in cases of navicular disease accentuate the lame-
ness. For this reason, in doubtful cases, the animal is sometimes shod
with a bar shoe and caused to trot.
As might be naturally expected in connection with a disease which is
at once so serious and so extremely common, various methods of treatment
with the object of effecting a cure have been adopted. Macqueen claims
that an animal in which lameness is not too pronounced may be suffi-
ciently relieved to enable it to work by applying a modified knocked-up
shoe each branch of which gradually increases in depth as we proceed to
the heels. The object is to ease the pressure of the flexor tendon on the
part. The toe is also shortened. W. Williams states that in the early
stages of the disease the " shoes are to be removed, the frogs allowed to
touch the ground ; blood is withdrawn from the toe or coronary plexus,
and the feet placed in a cold-water bath for several hours during the day
and in a poultice at night. . . . This method of treatment, with an
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NAVICULAR DISEASE
57
occasional purgative and a cooling diet, has proved most successful."
Special shoes, such as Allen's and Fitzwygram's, have also been
applied.
It is generally conceded that rest and a run out on soft, damp pasture
afford relief. An old method of treatment, which was once very
commonly practised, was to blister the coronet. Another method, which
was introduced by Sewell, and for which a considerable degree of success
was claimed, was counter-irritation by means of a seton passed through the
frog. The operation was performed with a curved seton needle. The
horn at the point of the frog was removed to allow the point of the
needle to pass out readily. The operation was performed in the standing
position. The limb was fixed with a knee hobble and a twitch applied.
The point of the needle is passed into the hollow of the heel, and then
through the plantar cushion and sensitive frog, to emerge at the point of
the frog. Having removed the handle, the needle with the tape is drawn
through the frog. The needle is then removed, the tape released, and its
ends tied. The tape is left in position for about a fortnight, being moved
frequently to facilitate drainage.
What appears to be a rational surgical method of treating some cases
is the operation introduced by Andre. It consists in exposing the
navicular bone, removing any necrosed or otherwise diseased areas, and
disinfecting the part. It is somewhat similar to the operation sometimes
performed in the treatment of gathered nail. The animal is cast and
placed under a general anaesthetic. The hoof is thinned at the junction of
the sole and frog. A V-shaped incision is made backwards from the point
of the frog, the arms of the V passing one along each lateral lacuna. The
horny frog is then dissected free from the plantar cushion and hooked
well back. Incisions are now made at the sides of the plantar cushion,
and this is dissected free from the underlying structures and hooked back
in a similar manner. The tendon of the flexor perforans is now exposed.
It is here much broader and thinner than higher up the limb, for it is
flattened and spread out over the back of the navicular bone. An incision
H
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58          THE SURGICAL ANATOMY OF THE HORSE
is next made through the tendon in the middle line and for a length of
about three-quarters of an inch. The edges of the tendon are then
hooked apart, and the posterior surface of the bone, so far as it is exposed,
examined. Necrosed areas are well scraped with the curette, and the
part disinfected. The structures mentioned are replaced and the foot
bandaged.
Notwithstanding the numerous efforts made and various methods
adopted, it may be stated that, in the present state of our knowledge of the
disease, there exists no remedial treatment for it.
Some of the foregoing methods for which success has been claimed in
the past are obviously contradictory. Blistering the coronet was evidently
based, as Moiler and Dollar point out, on erroneous diagnosis. Setoning
the frog created quite a furore for a time, and thousands of animals were
subjected to the operation, yet it is rarely, if ever, performed to-day.
Running out to grass affords relief, but this is now known to be only
temporary, and unscrupulous dealers occasionally trade upon this know-
ledge by offering an affected animal for sale immediately after a rest.
Whilst resection of the frog and plantar cushion, and exposing the bone by
making an incision in the perforans tendon as described above, might
enable one to treat the disease with successful results when the affection is
confined to necrosis of the exterior of the bone and on its posterior
surface, it can serve no useful purpose in those cases in which the
interior of the bone is affected. Nevertheless, since cases of the former
type are very common, it is an operation which might be attempted with
greater frequency in this country.
At present the best course to be adopted in cases of navicular disease
is to perform double plantar neurectomy, an operation which is fully
described in Vol. II. Although the operation is frequently followed by a
marked loss of action, its performance destroys sensation in the part, and
enables the animal to work for a longer period without suffering pain or
exhibiting lameness. It is, of course, not claimed that the operation has
any curative effect on the disease.
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FRACTURE OF THE THIRD PHALANX
59
FRACTURE OF THE THIRD PHALANX, OR PEDAL BONE
As already stated, a deep punctured wound of the foot due to a
gathered nail or some other such cause may be complicated by the
chipping off of a piece of the pedal bone. Occasionally the fracture does
not occur at the time of the original injury, but a portion becomes
necrosed, and later breaks away from the main portion of the bone. It
may occur as a complication of a severe tread or bruised heel, and has
also been observed in cases of suppurating corn.
The bone is encased within the hoof, and consequently accurate
diagnosis presents considerable difficulty. There is usually very severe
lameness. Some assistance may be obtained by tapping the hoof gently
over the seat of the injury; the resulting sound is somewhat hollow.
Lameness persists, and frequently a quantity of pus collects at the seat.
At times a small piece of bone is found in the discharge as in cases of
quittor or punctured wounds.
So long as the articular surface of the pedal bone is not implicated,
cases of fracture usually do well, and large portions of the bone may be
removed with successful results. Hurrell removed a portion three and
a half inches in length broken off the anterior border of the bone, and
the case made an uneventful recovery.
Treatment consists in removing the fractured piece and scraping the
surface from which it was broken. The wound is then disinfected and
treated ordinarily.
PYRAMIDAL DISEASE—LOW RINGBONE
To this condition the term "buttress foot" is frequently applied. It is
a chronic inflammation of the region of the pyramidal process, to fracture
of which it has been attributed. Cases have, however, been observed in
which fracture of the process is a result rather than a cause of the disease.
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60          THE SURGICAL ANATOMY OF THE HORSE
The condition is most frequently encountered in hind feet, but fore feet
are not uncommonly affected.
Owing to the situation of the injury, there is little external indication
of the injury in the early stages. The animal is lame, but, apart from a
restricted action of the extensor pedis, there is nothing characteristic in
the lameness. Gentle percussion over the process will reveal evidences
of pain. Symptoms of the acute stage, such as local heat and tenderness,
have frequently passed away before attention is directed to the seat of
the injury.
As the condition advances, local changes occur, leading to a marked
alteration in the conformation of the part, and leaving no doubt as to the
nature of the affection. The skin at the coronet becomes very much
thickened, and an indurated enlargement appears at the coronet in the
median line. To the touch it appears to be an indurated swelling not
unlike one due to dense fibrous tissue. It does not present the hardness
of an osseous enlargement. There is next a distinctive alteration in the
conformation of the hoof, the wall of which becomes divided into two
lateral portions separated by a prominent transversely-rounded ridge
which extends from the enlargement at the coronet to the toe. The
osseous nature of the subjacent enlargement at the coronet now becomes
apparent, and above it is a deep depression due to the fact that the inferior
extremity of the second phalanx is displaced backwards by the enormously-
developed pyramidal process. When disease is due to a blow received
over the summit of the pyramidal process, and the latter is not fractured,
it becomes inflamed, and the cartilage becomes removed from its posterior
or articular surface, this removal commencing at the summit. The front
and sides of the process become greatly enlarged owing to the develop-
ment of new bone. The depressions at the sides of the process, in
which are inserted the antero-lateral ligaments, become filled up, and
evidences of the presence of the exostosis make their appearance at the
coronet.
As will naturally be expected, treatment of such an affection will be
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PYRAMIDAL DISEASE—LOW RINGBONE              61
of little avail. The application of counter-irritants, so frequently adopted,
has no beneficial effects. The only course open is to prolong the animal's
working period for a few months by performing neurectomy. If the
fore foot be affected, double plantar neurectomy should be performed
(Vol. II.), and in the case of the hind foot double plantar or posterior
tibial neurectomy (Vol. III.).
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CHAPTER II
THE THORAX AND BACK
In the horse the cavity of the thorax approaches the conical in shape.
The cone, however, is compressed from side to side, and this is particularly
so in the anterior part of the cavity. The apex of the cone is placed in
front, and is bounded laterally and inferiorly by the first pair of ribs, and
superiorly by the body of the first dorsal vertebra. The opening so
bounded may be regarded as the entrance to the chest, and through it
the oesophagus and trachea, together with the blood-vessels of the head,
neck, and fore limbs, and the vagi, phrenic and other nerves, pass. The
diaphragm forms the base of the cone, and the surface which is directed
towards the thorax is very convex. Moreover, it slopes downwards and
forwards, so that the antero-posterior dimension of the cavity is much
greater above than below.
The eighteen pairs of ribs and the intercostal muscles bound the
cavity laterally, the sternum below, and the bodies of the dorsal vertebrae
form its superior boundary.
It is a matter of considerable clinical importance to be able to locate
accurately the position of the diaphragm. To enable this to be done, it
should be remembered that the soft fibres of its muscular rim are attached
inferiorly across the upper face of the ensiform cartilage, the line of their
attachment being placed about an inch behind the posterior end of the
body of the sternum. From this central point the line ascends obliquely
upwards and backwards. The fibres may be attached to the upper ends
of the costal cartilages or to the distal extremities of the ribs themselves.
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63
THE THORAX AND BACK
By tracing a line in the living animal from the front of the ensiform
cartilage upwards over the last ten chondro-costal joints, a fairly accurate
indication will be obtained of the line of attachment. Remembering
also that its thoracic surface is convex and its abdominal surface is
correspondingly concave, those organs in the abdominal cavity which
are in immediate relationship to its posterior surface, and particularly
those placed near the median line, are afforded a certain amount of
protection by the posterior members of the series of ribs.
Anteriorly the scapula runs obliquely downwards and forwards over
the chest wall, its dorsal angle usually extending as far backwards as the
eighth rib. From its glenoid cavity the humerus runs downwards and
backwards to the elbow. Filling in the angle formed between these
bones is the large mass formed by the caput muscles. The front of the
chest is thus well protected on either side. Running downwards from
the ventral aspect of the scapula is the serratus magnus muscle, which
inferiorly forms eight thick fleshy, tooth-like processes which are attached
to the first eight ribs. The last four members of this series of muscular
processes dovetail with similar processes formed by the anterior end of
the external oblique muscle of the abdomen. More inferiorly we have
the posterior deep pectoral muscle, the posterior portion of which is
subcutaneously placed. This is a thick fleshy muscle, and it arises from
the abdominal tunic covering the rectus abdominis and obliquus abdom-
inis externus muscles, from the tips of the cartilages of the last four
sternal ribs, and from the lateral surface of the sternum immediately below
these cartilages. The dorsal portion of the trapezius muscle is thin and
sheet-like. It arises from the summits of the spines of the first few
dorsal vertebrae, and its fibres run obliquely downwards and forwards to
the tubercle of the spine of the scapula, where they are inserted.
The muscular layer covering the ribs bounding the posterior half of
the thorax is much thinner. The latissimus dorsi arises from the superior
spines of the vertebras from the fourth dorsal to the last lumbar. At its
origin it is a sheet-like, thin aponeurosis. The fibres run downwards
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64           THE SURGICAL ANATOMY OF THE HORSE
and forwards, and are succeeded by a thick muscular portion, which
contracts and passes in between the fore limb and chest wall to run to
its insertion into the internal tubercle of the humerus. Its tendon of
origin is continuous posteriorly with the fascia covering the gluteal
muscles. Inferiorly the tendon blends with the oblique muscles of the
abdomen, and here it is adherent to the ribs. The latissimus dorsi is seen
after the removal of the skin with the thin panniculus carnosus muscle,
as also is the serratus magnus.
Deeply seated to the latissimus dorsi are the serratus anticus and
serratus posticus muscles, and in some cases these are intimately adherent
to the latissimus dorsi. The serratus posticus has an aponeurotic origin
from the spines of the vertebra from the eleventh dorsal to the second
lumbar, and this is succeeded by eight or nine thin muscular processes
which are attached to the outer surfaces and posterior borders of the last
eight or nine ribs in their upper thirds. It represents the serratus
posticus inferioris of man. The serratus anticus arises similarly from the
superior spines of the second to the thirteenth dorsal vertebrae, and is
inserted into the outer surfaces and anterior borders of the fifth to the
thirteenth ribs. The serratus anticus and posticus muscles represent the
superficialis costarum of Percivall.
By removing the serratus anticus and posticus muscles, the transversalis
costarum
is exposed. This runs across the outer surfaces of all the ribs
of its side in their upper third. It does not run parallel to the spine, but
gradually approaches it as it passes forwards. Its fibres run forwards and
slightly downwards. They arise from the transverse processes of the first
and second lumbar vertebra? and from the anterior edges of the ribs, and
are inserted into the posterior borders of the first thirteen ribs and into
the transverse process of the last cervical vertebra.
Above the transversalis costarum is a large muscular mass which fills
in the angle formed between the ribs and the vertebral spines, so that the
upper ends of the ribs are deeply seated and well protected. This mass
is the kngissimus dorsi muscle, which is the longest and most powerful
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THE THORAX AND BACK                             65
muscle in the body, extending from the sacrum to the neck. It is
particularly bulky in the region of the loins, and clothes the sides of the
vertebral spines of all the lumbar and dorsal vertebrae. It is thus impli-
cated in many cases of fistulous withers, and it is chiefly due to the great
bulk of this muscle that sinuses of this region can become so extensive
without involving the joints of the ribs or vertebrae. It has a most
complex arrangement. It arises from an area on the sacral surface of the
ilium between the crest and the sacro-iliac joint, and from a powerful
sheet of fascia which is attached to the supraspinous ligament or to the
spines of the lumbar and dorsal vertebrae. Its insertions are into the
transverse and articular processes of the lumbar vertebrae, the transverse
processes of the dorsal vertebrae, and to the ribs, its attachment to the ribs
being limited inferiorly by the upper border of the transversalis costarum
muscle. Anteriorly it divides into two portions, between which the
complexus and trachelo-mastoideus muscles emerge. The point of
division is opposite the fifth dorsal vertebra. The upper division is
ultimately inserted into the superior spines of the third, fourth, fifth, and
sixth cervical vertebrae, the lower division into the ribs and the last four
cervical and first four dorsal transverse processes.
If the longissimus dorsi be removed, two sets of little muscles will be
exposed. These are the levatores costarum and the semispinalis of the back
and loins. The former are in a series placed at the upper ends of the
intercostal spaces, where they take the place of the external intercostal
muscles. They arise from the transverse processes of the dorsal vertebrae,
and each bundle runs downwards and backwards, broadening out as it
descends to become inserted into the outer surface of the more posterior
of the two ribs which bound the space in which the muscle is placed.
They are frequently absent in the first two or three spaces.
The semispinalis covers the sides of the superior spines from the
cervical region to the sacrum. It consists of a number of bundles
running obliquely upwards and forwards. The bundles arise from the
anterior border of the sacrum, the articular processes of the lumbar
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66          THE SURGICAL ANATOMY OF THE HORSE
vertebra?, and the transverse processes of the dorsals. Each bundle is
attached to the superior spine of the third or fourth vertebra in front of
the one from which it takes origin. These little muscles are in series
with the semispinalis of the neck and with the curvator coccygeus
muscle.
The External Intercostal Muscles.—Each of these is placed in an
intercostal space. It runs from within a short distance of the spine (the
upper extremity of the space is occupied by one of the levatores costarum
muscles) to the inferior extremities of the ribs. The fibres may be said
to arise from the posterior border of the anterior rib bounding the space,
and to run obliquely downwards and backwards to be attached to the
anterior border of the posterior rib.
The Internal Intercostal Muscles.—There is also one of these in each
intercostal space. They extend into the spaces between the costal
cartilages, and are thus longer than the external intercostals. Their fibres
also take a different direction, for they run obliquely downwards and
forwards, and are generally regarded as arising from the posterior rib and
its cartilage and as being inserted into the anterior rib and cartilage which
bound the space in which the muscle is placed. The deep face of
the internal intercostals is lined by the parietal layer of the pleura.
The Lateralis Sterni.—This arises from the outer surface of the first
rib, and runs downwards and backwards obliquely, crossing the second
chondro-costal joint and the third and fourth costal cartilages. It is
inserted into the side of the sternum.
The Triangularis Sterni.—This is sometimes called the transversus
thoracis. It is a thin flat muscle which lies on the superior aspect of the
sternum, and thus partially covers the floor of the thorax. It arises from.
the lateral border of the sternum and the edge of the xiphoid cartilage.
It is inserted into the cartilages of the second and the eighth ribs and into
the aponeurotic covering of the internal intercostal muscles. Its superior
face is clothed by the pleura, and the muscle conceals the internal thoracic
vessels.
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THE THORAX AND BACK                             67
The Anterior Superficial Pectoral. — This muscle arises from the
anterior portion of the inferior border of the sternum, and is inserted into
the curved ridge which descends from the deltoid tubercle of the humerus,
together with the mastoido-humeralis. Its superficial face is distinctly
convex, and it forms a marked prominence at the front of the chest, which
is easily recognized in the living animal. At the middle line it is in close
apposition to the corresponding muscle of the opposite side, and the skin
is grooved between the two muscles. Another groove runs obliquely
downwards between the elevation caused by this muscle and that due
to the underlying mastoido-humeralis. In this groove are placed the
cephalic vein and the descending division of the inferior cervical artery,
whilst some slender cutaneous branches from the sixth cervical nerve cross
it. These structures have to be avoided when operating on the front of
the chest.
The Posterior Superficial Pectoral arises from a median fibrous cord
which separates it from the corresponding muscle of the opposite side, and
from the whole of the inferior border of the sternum, with the exception
of the first inch and the portion behind the sixth costal cartilage. It is
inserted into the superficial fascia on the inner aspect of the forearm, and a
small band of fibres in front, about an inch in breadth, is inserted with the
anterior superficial pectoral into the humerus. This muscle covers the
median nerve and the posterior radial vessels on the inner aspect of the
elbow.
The Anterior Deep Pectoral arises from the lateral aspect of the first
four segments of the sternum and from the cartilages of the first four
ribs. It is a fleshy muscle which passes at first forwards, and then curves
upwards and backwards, running over the front of the shoulder slightly
to the inner side. Ascending in front of the supraspinatus, it is
inserted into the fascia covering this muscle near the cervical angle of the
scapula.
The Posterior Deep Pectoral is much the largest of the four pectoral
muscles. Its posterior portion is superficially placed, and forms an
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68           THE SURGICAL ANATOMY OF THE HORSE
elevation on the antero-inferior portion of the lateral aspect of the chest.
It arises from the abdominal tunic which spreads over the rectus
abdominis and obliquus abdominis externus muscles, from the lateral
aspect of the last four segments of the sternum, the xiphoid cartilage, and
the cartilages of the fifth, sixth, seventh, and eighth ribs. It is
inserted into the internal tuberosity of the humerus, into the tendon of
origin of the coraco-radialis muscle, and into the thick fascia which keeps
this tendon in the bicipital groove.
The action and nerve and blood supply of the foregoing muscles are
given in the table at the end of this volume.
ARTERIES AND VEINS OF THE CHEST WALL
The Intercostal Arteries.—There is one artery in each intercostal space,
so that there are seventeen on either side of the thorax in the horse. The
first comes from the superior cervical artery, the second, third, and fourth,
from the subcostal branch of the dorsal artery, and the remainder from the
posterior aorta itself.
Each leaves the superior aspect of its parent vessel, and, running across
the body of a vertebra, passes beneath the sympathetic cord to reach the
upper extremity of an intercostal space. It gives off branches which are
distributed to the pleura and to the vertebra, and then splits into two
divisions. The upper, sometimes referred to as the ramus dorsalis or
dorso-spinal artery, gives off" a branch which passes into the spinal canal
through the intervertebral foramen. This branch distributes a number
of small vessels to the meninges of the cord, and then penetrates the dura
mater and joins the middle spinal artery. The dorso-spinal artery then
passes upward, and is expended in the muscles lying in the costo-vertebral
groove. Branches are also distributed to the skin covering this region,
and a number of these are seen when making a superficial dissection of
the part.
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ARTERIES AND VEINS OF THE CHEST WALL 69
The Inferior Division, Ramus Ventrails, or Intercostal Artery Proper.
This is much the larger of the two divisions. At first it lies under cover
of the pleura. It then descends the intercostal space between the external
and internal intercostal muscles, and in a groove on the posterior border
of the rib. It is accompanied by the intercostal vein and nerve, the vein
being the most anterior, and the nerve being placed behind the artery. In
the lower two-thirds of the space the vessel inclines slightly towards the
inner face of the rib, and is overlapped by its hinder edge. It is now
usually found between the internal intercostal muscle and the parietal
layer of the pleura. The relationship of these structures is of importance
in performing operations on the chest wall, to be described hereafter.
Branches are distributed from these divisions to the ribs, the pleura, and the
muscles of the chest wall, and where the wall of the thorax is not covered
by the upper end of the fore limb a number of small branches pass out-
wards, pierce the muscles, and are distributed to the skin and panniculus
carnosus at the inferior extremities of the intercostal spaces.
The first six intercostal arteries anastomose with ascending vessels,
which are branches of the internal thoracic artery. The next six
or seven contract similar anastomoses with branches from the asternal
division of the internal thoracic artery. The remainder pass out of the
intercostal spaces to enter the wall of the abdomen, in the muscles of
which they are expended, and where they anastomose freely with branches
from the abdominal arteries, and some also with branches of the circumflex-
iliac artery.
The Dorsal Artery.—On the left side this is a separate vessel detached
as the first collateral branch of the intrathoracic portion of the axillary
artery. On the right side, at its origin, it forms a common trunk with
the superior cervical artery. It ascends to the second intercostal space
between the mediastinum, passing across the oesophagus, longus colli, and
sympathetic nerve trunk. In the interstice between the levator anguli
scapula? and serratus magnus muscles it splits into a number of branches,
which are distributed in various directions. Most of these pass to the
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70          THE SURGICAL ANATOMY OF THE HORSE
upper portion of the withers and base of the neck, and supply the muscles
of these regions. These branches are so numerous that it is almost
impossible to avoid them when operating on such cases as fistulous
withers.
The Subcostal Artery is given off as a collateral branch of the dorsal or
dorso-cervical artery before the latter leaves the cavity of the thorax. It
passes backwards alongside the sympathetic cord, over or in close proximity
to the joints formed between the ribs and vertebrae. As already stated, the
second, third, and fourth intercostal arteries are branches of this vessel.
The subcostal artery usually terminates by penetrating the muscles in the
costo-vertebral groove. It may, however, anastomose with a branch from
the fifth intercostal.
The Internal Thoracic Artery.—This is the last branch of the intra-
thoracic portion of the axillary artery. It is detached from the parent
vessel at the first rib, down the inner surface of which it runs under cover
of the pleura. It then curves backwards, and disappears beneath the
triangularis sterni muscle. It runs over the chondro-sternal joints, near
the eighth of which, at the anterior border of the xiphoid cartilage, it
divides into the asternal and anterior abdominal arteries.
This vessel is also called the internal mammary artery, and during its
course it gives off three sets of branches. The members of one set pass
upwards to the mediastinum and pericardium. The inferior set are
much larger vessels. They pierce the intercostal spaces and anastomose
with branches of the external thoracic artery. Thirdly we have branches
which pass into the intercostal spaces, where they anastomose with the
corresponding intercostal arteries.
The anterior abdominal artery will be followed later, when dealing
with the wall of the abdomen.
The Asternal Artery appears from beneath the triangularis sterni
muscle, and passes up the ninth costal cartilage on the thoracic side.
Near the upper end of this cartilage it pierces the origin of the diaphragm
from before backwards, and terminates by anastomosing with one of the
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ARTERIES AND VEINS OF THE CHEST WALL 71
intercostal arteries. It detaches a number of small branches to the
muscular rim of the diaphragm, branches to the intercostal spaces, and
several branches which are expended in the transverse muscle of the
abdominal wall.
The External Thoracic or External Mammary Artery.—This vessel
leaves the axillary artery in front of the first rib, round the anterior border
of which it curves. It splits into a number of branches, which are
distributed to the superficial and deep pectoral muscles.
The Intercostal Veins.—These are placed one in each intercostal space,
in front of the corresponding intercostal artery. In the manner in which
they discharge their contents, the veins differ on the right and left sides.
The first vein of the right side joins the superior cervical vein, the second,
third, and fourth, join the dorsal vein, and the remainder the great azygos
vein. On the left side the first vein also joins the superior cervical, but
the left dorsal vein receives the next ten or eleven, whilst the last five or
six empty themselves into the great azygos vein.
NERVES OF THE CHEST WALL
Quite a large number of cutaneous nerves are detached from the dorsal
spinal nerves. Some of these become superficially placed near the tips of
the superior spines; others appear in a series along the longissimus
dorsi muscle. All these are derived from the superior primary divisions
of the dorsal nerves. Others come out in a series along the side of the
chest. These are branches of the intercostal nerves.
There are eighteen Dorsal Nerves. Each leaves the intervertebral
foramen behind the vertebra from which the nerve is named. Whilst in
the foramen it splits into superior and inferior primary divisions. The
former is distributed to the muscles which lie in the costo-vertebral
groove, the largest of which is the longissimus dorsi, and it gives off
cutaneous branches as described above. The inferior primary divisions
comport themselves as follows :
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72          THE SURGICAL ANATOMY OF THE HORSE
That of the first nerve is almost entirely expended in assisting to form
the brachial plexus, and gives off a very slender twig which does not
extend the whole length of the first intercostal space. The second
nerve detaches a slender contribution to the brachial plexus, and is then
continued as the second intercostal nerve. From the third to the seven-
teenth the inferior primary divisions are directly continued as the inter-
costal nerves,
whilst in the case of the eighteenth nerve this division
descends behind the last rib.
The second to the seventh intercostal nerves, inclusive, pass out through
the pectoral muscles, and become superficially placed on the antero-
inferior aspect of the chest. The remaining intercostals leave the
intercostal spaces inferiorly, and ramify in the wall of the abdomen.
A large branch is detached from each intercostal nerve about midway
down the intercostal space. These branches pass outwards, and are
distributed to the skin and skin muscle. The intercostal nerves ^also
supply the muscles of the same name.
The subcutaneous thoracic nerve runs backwards along the wall of the
thorax in company with the spur vein. The course of the latter can
usually be determined in the living animal without difficulty. The nerve
appears near the upper border of the posterior deep pectoral muscle. It
comes from the brachial plexus, its fibres being derived from the eighth
cervical and the dorsal roots. It follows the spur vein to the region of
the flank, and during its course it distributes branches which ramify on
the deep face of the panniculus carnosus with the perforating branches of
the intercostal nerves described above.
This nerve must be carefully avoided when puncturing the chest.
TFIE DIAPHRAGM
This is a muscular and tendinous sheet which forms the partition
between the thoracic and abdominal cavities. Its outline is usually referred
to as resembling that of the heart of-playing cards. It takes a direction
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THE DIAPHRAGM
73
which is downwards and forwards from the lumbar vertebras to the ensiform
cartilage. When relaxed its anterior or thoracic surface is markedly convex,
bearing some resemblance to a laterally compressed dome. This surface is
covered by the pleura, and is related to the bases of the lungs. The
posterior surface is correspondingly concave, and is clothed for the greater
part by the peritoneum. The stomach, liver, spleen, and intestines, are
related to this surface.
The diaphragm consists of a muscular rim, a tendinous centre, and
two crura, or muscular pillars. The rim consists of soft fibres; these are
attached on the superior face of the xiphoid cartilage, about an inch
behind the posterior border of the body of the sternum, and on either
side of this to the cartilages of the ninth to the eighteenth ribs inclusive,
or to the ribs themselves just above the joints formed between them and
their cartilages. These attachments form digitations which are in close
relationship to the attachments of the transversalis abdominis muscle, the
asternal arteries passing between them. From these attachments the
muscle fibres are directed inwards, and end in the tendinous centre, where
their terminations are indicated by a denticulated line.
The tendinous or phrenic centre, sometimes called the mirror of
Helmont, is of a dull white colour, and is made up of glistening fibres
which interlace in various directions.
There are two pillars or crura, right and left. The right crus is
attached through the medium of the inferior common ligament to the
bodies of the first four or five lumbar vertebrae. It is the larger pillar,
and its fibres descend towards the middle of the tendinous centre, where
most terminate. Some, however, pass outwards to the right and extend
towards the muscular rim. The left crus arises similarly from the bodies
of the first two lumbar vertebras and to the left side. Its fibres pass
downwards into the tendinous centre, and occasionally curve outwards
towards the left side and extend to the muscular rim.
On either side the pillars a portion of the superior edge is free, and
curves over the inferior aspect of the psoas magnus and parvus muscles.
K
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74          THE SURGICAL ANATOMY OF THE HORSE
This free curved portion is the lumbo-costal arch, sometimes called the
arcuate ligament.
The sympathetic trunk passes backwards to the lumbar region between
this edge and the surface of the psoas parvus muscle close to the spine.
More outwardly the great splanchnic nerve passes between the arch and
the edges of the psoae muscles.
Between the two crura and beneath the last dorsal vertebra is the
hiatus aorticus, through which the posterior aorta and the initial portions
of the great azygos vein and the thoracic duct are transmitted.
The foramen sinistrum is placed between the fibres of the right crus,
slightly to the left of the middle line. It gives passage to the oesophagus,
the pleuro-cesophageal division of the gastric artery, and the continuations
of the vagi nerves.
The foramen dextrum pierces the tendinous centre about one inch to
the right of the middle line. The posterior vena cava passes from the
abdomen to the thorax through this opening, and the margin of the
opening is intimately adherent to the wall of the vessel. Here the
phrenic sinuses discharge their contents into the vena cava.
In relation to the skeleton, the positions of the foramina are as follows :
The hiatus aorticus is, as already stated, in the same vertical plane as
the eighteenth dorsal vertebra, and just below it. The foramen sinistrum
is between two and three inches below the thirteenth dorsal vertebra, and
the foramen dextrum about six inches below the twelfth, when the dia-
phragm is in the position of expiration. During inspiration the last two
foramina are drawn slightly backwards, though there is very little move-
ment of the foramen dextrum, owing to the attachment to the vena cava,
already referred to.
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DIAPHRAGMATIC HERNIA
75
RUPTURE OF THE DIAPHRAGM—DIAPHRAGMATIC
HERNIA
Occasionally, as a result of extreme tympany, the diaphragm becomes
ruptured, and a portion of one or other of the abdominal organs protrudes
through the aperture into the thorax, producing a hernia of the diaphragm.
Most frequently it is the result of some sudden fall. In horses, in which it
is more commonly encountered than in any other domesticated species, it
sometimes results from the animal's rearing and coming over on its back.
In some cases death quickly results, owing to pressure upon the lungs by
some large portion of a displaced organ, bringing about asphyxia. In
other cases symptoms are presented not very unlike those of a broken-
winded animal. Positive diagnosis is most difficult. If the condition
be suspected, an unfavourable prognosis should be given, as the case is not
one which is amenable to successful surgical treatment.
THE PLEURA
These are two serous membranes placed one in each half of the
thorax ; they are similar to other serous membranes, for each is arranged
after the manner of a clsoed sac with parietal and visceral portions.
The parietal pleura lines the walls of the corresponding side of the
chest. On the lateral wall it adheres to the inner surfaces of the ribs and
intercostal muscles. This portion is referred to as the costal pleura. On
the posterior wall it is intimately adherent to the anterior face of the
tendinous portion of the diaphragm, and loosely to its muscular rim,
forming the diaphragmatic pleura. Near the median sagittal plane it
forms, with the corresponding layer of the other sac, what is known as
the mediastinal pleura. The ligament of the lung, or ligamentum latum
pulmonis, consists of a double fold of pleura containing a quantity of
elastic tissue, which passes from the diaphragm along the mediastinum to
the back of the root of the lung.
.•
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jb          THE SURGICAL ANATOMY OF THE HORSE
At the root of the lung the pleura is reflected on to the surface of the
latter, which it almost entirely covers, forming the visceral pleura. The
two lungs form an intimate attachment behind these roots, so that an area
of each lung here is uncovered by pleura.
The right pleural sac forms a special fold which extends upwards
between the accessory and main lobes of the right lung. Between the
two layers of this fold the posterior vena cava and the right phrenic
nerve run.
The portions of the pleura described above form a continuous mem-
brane arranged as a closed sac, the interior of which is the pleural
cavity. In the living animal, however, this is strictly a potential cavity
when the animal is in a normal healthy condition, the parietal and
visceral layers being everywhere in close apposition. The opposed
surfaces of these layers are extremely smooth, and present a glistening
appearance, since they are moistened by a quantity of serous fluid. This
being so, the smooth surfaces which are in apposition glide freely over
one another, so that friction with the chest wall during the movements
of the lungs is restricted, and the movements are greatly facilitated. A
section through the wall of the sac reveals the fact that it is made up of
a single layer of endothelial cells, which line its free surface (and there-
fore the two surfaces which are in apposition), and these are supported
by a layer of fibrous connective tissue in which the nerves and blood and
lymphatic vessels ramify.
The above is the condition of a healthy membrane. In cases of
pleurisy the smooth surfaces in the early stages become dry and more or
less roughened. The movements of the lungs and chest wall are attended
by most acute pain. Consequently there is a natural effort on the part
of the animal to restrict them by fixing the chest and " breathing from
the flank." In the later stages, when an abnormal amount of inflam-
matory exudate accumulates between the two layers of the sac, these
layers become separated, so that the above evidences of pain disappear.
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PARACENTESIS THORACIS
77
PARACENTESIS THORACIS
This is the technical term applied to the operation of tapping the
chest with the object of removing the inflammatory exudate referred to
above, or other liquid accumulations in the pleural sac. Such accumulated
material exerts undue pressure upon the lungs, thus interfering with
respiration, and also upon the heart and great vessels, obstructing the
action of the former and impairing the circulation. By the removal of
the material such pressure is relieved, but the operation has no effect apart
from this mechanical relief, and cannot be regarded as curative.
In cases of accumulated septic material the beneficial effect of its early
removal is obvious. Good results frequently follow the performance of
the operation in cases of septic wounds penetrating the chest wall, for the
purpose of washing out the chest cavity with antiseptics.
Since there is usually in the horse a natural communication through
the posterior mediastinum, between the right and left pleural sacs, the
fluid passes from one sac to the other; and if there is evidence of liquid
in both sacs, the right side is selected for the operation. This will avoid
injury to the heart. Probably the best guide to the seat of puncture is
the spur vein. The position of this, as already stated, is plainly visible
in the living animal. Below this the upper border of the posterior deep
pectoral muscle can also be detected. Both these structures are to be
avoided, and the seat should be above the vein, but quite close to it, in
order that the punctured opening may be as near the floor of the chest
as possible. The opening should be made in the fifth, sixth, or seventh
intercostal space, and immediately in front of the posterior rib bounding
the space, to keep quite clear of the intercostal vessels and nerve. A
common method of arriving at the seat is to take a span behind the point
of the elbow and on a level with it.
The operation is performed with a trocar and canula, the former
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78          THE SURGICAL ANATOMY OF THE HORSE
having a length of from one and a quarter to two and a half inches, and
the latter a diameter of from a quarter to half an inch.
It is unnecessary to cast the animal. The instruments and operation
area should be rendered thoroughly aseptic. The skin is usually movable
on the chest wall. It should be drawn slightly forwards, and held in
position with three fingers of the left hand (the index and pollex are left
free to seize the canula).
The introduction of the point of the trocar is facilitated by making
a small punctured incision in the skin with a scalpel. This should always
be done in cases where the skin is thick. The instrument is now taken
in the right hand, the index finger being extended along the canula, the
handle in the hollow of the hand, and the instrument held between the
thumb and remaining fingers perpendicular to the surface of the chest
wall. The index finger is utilized to guide the point of the trocar to
the exact seat of puncture, and trocar and canula are pressed through
the wall into the thorax. The canula is now seized between the thumb
and finger of the left hand, and with the right the trocar is steadily
withdrawn. The point of the index finger is immediately placed over
the entrance to the canula. This is to prevent an inrush of air into the
chest. The finger is removed when the pressure of liquid can be felt.
It is essential that the removal of the liquid should be gradual, so that
the pressure on the heart and vessels may not be relieved too suddenly.
Cases are not infrequently lost through sudden change in the blood-
pressure in the chest. Occasionally the lumen of the canula becomes
blocked by flocculi of lymph material. This should be removed by
means of a probe. At other times the surface of the lung presses against
the opening, and thus arrests the flow of liquid. A little side-to-side
movement of the canula will generally prove effective in these cases.
The position of the puncture is at a higher level than the lowest limit
of the floor of the thorax, Consequently it is impossible to evacuate the
whole of the contents. Even if possible, it would be inadvisable to do so,
inasmuch as many practitioners advise that not more than about six quarts of
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THE LUNGS
79
liquid should be removed at one time. For the reasons stated above, rather
than remove more, it is preferable to perform the operation again later.
Having removed as much liquid as is considered desirable, the trocar
is thoroughly cleansed and reintroduced into the canula. Both are now
carefully removed, the skin is allowed to slip back by removing the left
hand, and the wound is dusted over with dry dressing, or a layer of iodo-
form and collodion applied.
THE LUNGS
During life the lungs fill up the greater part of the thoracic cavity.
The right lung is much larger than the left. Each may be said to present
two surfaces, three edges, an apex, and a base.
The external surface is convex, and is moulded on to the inner surface
of the chest wall, to which it is related. It is the more extensive of the
two surfaces, and is covered by the visceral layer of the pleura. This is
frequently referred to as the costal surface.
The internal or mediastinal surface presents depressions for the accom-
modation of the organs placed between the layers of the mediastinum.
Thus superiorly there is a longitudinal groove for the posterior aorta. Below
and almost parallel to this is another somewhat shallower depression for
the oesophagus, which is much deeper on the left lung than on the right.
Antero-inferiorly is a deep cavity with a circumferent border. This
accommodates the heart. The circumference is incomplete, and presents a
deep notch inferiorly which permits the heart to come into apposition
with the chest wall—a point of considerable clinical and surgical impor-
tance. Postero-superiorly to this cardiac depression is the root of the
lung. This is made up of the bronchus, which is placed superiorly, the
pulmonary veins, placed inferiorly, and the pulmonary artery, the entrance
to which is placed in front of the root, between the bronchus and
pulmonary veins. In addition we have the nerves and lymphatics,
together with connective tissue. Below the pulmonary veins on the right
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80          THE SURGICAL ANATOMY OF THE HORSE
lung a channel commences at the posterior border of the cardiac depres-
sion, and passes longitudinally backwards, to be continued on to the
diaphragmatic surface. Along this the right phrenic nerve and the
posterior vena cava run, and a small flap of lung tissue is incompletely
separated by them from the main body of the organ. In front of the
cardiac depression a small area of this surface is flattened, and is applied to
the anterior mediastinum.
The base is related to the diaphragm, on the anterior surface of which
it is moulded. It is consequently concave. The base of the right lung
shows the fissure in which the posterior vena cava and right phrenic
nerve run, and which cuts off a small portion from the main body, as stated
above.
The apex is narrow but rounded, and extends forwards to near the
entrance to the thorax.
The superior or vertebral border is almost straight. It is thick and
rounded transversely, and lies in the groove between the bodies of the
vertebrae and the ribs. The inferior border is thinner and shorter, and
anteriorly presents a deep notch, which is smaller on the right lung than
on the left. The remaining border surrounds the diaphragmatic surface.
It is thin and sharp, and lies between the wall of the thorax and the
muscular rim of the diaphragm.
The above is a description of the lung in situ and in the ordinary con-
dition of distension. As soon as the thoracic cavity is opened, the lung
loses its proper conformation, collapses, and its size is reduced by about
two-thirds. The ordinary form as described is due to distension of the
highly elastic lung tissue by pressure of ther air in the lungs.
The colour of the lungs varies. During life it is pink. After death,
if the animal has not been bled, it is dark red, but in animals which have
been bled freely, as for dissection, the colour is a greyish-red. The foetal
lung is greyish in colour. It does not crepitate and is of a firmer consis-
tency. Relatively the organ is smaller, and, as is well known, it sinks in
water, whereas lung tissue which has once contained air floats.
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THE PERICARDIUM
81
THE PERICARDIUM
This is the name given to the sac in which the heart is placed. It is
situated between the layers of the middle mediastinum, and therefore near
the middle of the thorax. It consists of an external bag which is fibrous
in structure, and between the inner aspect of which and the exterior of
the heart itself is a serous membrane.
In general form it bears some resemblance to the organ which it
contains, and is thus somewhat conical ; superiorly it is pierced by the
large vessels which enter or leave the heart, and the fibres of the sac
blend with the outer coats of the vessels. The apex of the cone is
attached to the floor of the thorax, the area of its attachment being limited
anteriorly by a transverse line drawn through the third chondro-sternal
joints, and posteriorly by one drawn an inch in front of the inferior
attachment of the diaphragm. Although thin, the fibrous layer is tough,
and is not elastic.
Each lateral surface is crossed in its upper third by one of the phrenic
nerves, above which, on the left side, two cardiac nerves are observed to
pierce the sac, and at a still higher level the pneumogastric nerve of this
side passes backwards, and detaches its inferior laryngeal branch before
leaving the pericardium. These surfaces are almost entirely concealed
by the lungs, to which they are related, but inferiorly a small area on
each side lies in close apposition to the wall of the thorax. This area is
much larger on the left side, and extends from the third intercostal space
to the fifth. On the right side the area of contact is limited by the third
and fourth ribs. This is a point of ccnsiderable surgical importance, for
it indicates the best seat for operation when puncturing the pericardium.
Its base extends forwards to the level of the second intercostal space, and
backwards to the sixth. During dissection the mediastinal pleura can be
readily stripped off the outer surface of the sac over which it is spread.
Like all other serous membranes, that of the pericardium consists of
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82          THE SURGICAL ANATOMY OF THE HORSE
parietal and visceral layers. The parietal layer lines the deep face of the
fibrous sac, to which it is intimately adherent. Superiorly it is reflected
around the roots of the pulmonary vessels and the aorta, and becomes
continuous with the visceral layer. The latter envelops the aorta and
pulmonary artery, covers a small portion of the pulmonary veins near
their attachment to the roof of the left auricle, and the terminations of
the anterior and posterior Venae cavas. It then passes on to the surfaces
of the auricles and ventricles. It is everywhere in close relationship to
the wall of the heart and great vessels, excepting where it bridges over
the transverse and vertical grooves. Here it lies on the fat usually
accumulated in the grooves and on the coronary arteries.
The free surfaces of these two layers of serous membrane are smooth,
and are formed by a single layer of endothelial cells. They are kept
moist by serous fluid, of which normally there is present only a very
small quantity, so that there is, strictly speaking, only a potential cavity
in the sac. In abnormal conditions of the membrane, it frequently
happens that an abnormal amount of fluid accumulates in the sac, the
parietal and visceral layers become widely separated, and we have an
actual cavity between them.
TAPPING THE PERICARDIUM
This operation is performed for the removal of fluid which has
accumulated within the pericardial sac. It is most frequently per-
formed in the dog and ox. Should it be necessary in the horse, the
seat of operation selected should be on the left side, between the
fourth and fifth ribs (see Plate VIIL), where, owing to the greater size
of the notch in the lung on this side, the pericardium comes into close
apposition with the wall of the thorax. The operation of paracentesis
thoracis must first be performed; and having introduced the instrument
into the chest, great care must be taken, when puncturing the wall of the
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INJURIES TO THE CHEST WALL                     83
pericardium itself, to avoid injury to the heart. For this reason the trocar
employed should taper sharply to a point—i.e., the sharpened end should
be short.
INJURIES TO THE CHEST WALL
Injuries to the soft parts of the chest wall are frequently due to
collisions, and to falling on loose stones or hard, uneven ground. The
point of a shaft may bruise, or even penetrate, the wall. In pit ponies the
wall is frequently damaged by the sharp edges or angles of the " tubs."
Occasionally a sharp body passes between the shoulder or arm and the
wall, and leads to serious injury to the large vessels and nerves of this
region. Such cases are frequently fatal.
Prognosis must, of course, depend upon the seat and extent of the
injury. A penetrating wound at the front of the chest must always be
regarded with suspicion, particularly if near the base of the neck. In such
cases the trachea and large blood-vessels may be involved, or even the
vagi, with fatal results. Wounds confined to the muscles usually heal
well, even when extensive and lacerated. If as a complication the scapula
or humerus be fractured, fatal septicaemia usually results. A favourable
prognosis may usually be given if lameness is not very pronounced and
there is only a slight elevation of temperature'.
Should the chest wall be penetrated, pneumothorax, hemothorax, or
pleurisy, may follow. Great care should be exercised when examining a
wound with the object of ascertaining whether the wall is penetrated. A
conclusion can frequently be arrived at simply by making a superficial
examination of the wound, observing the direction which it takes, and
noting the instrument by which it has been produced. The use of
probes, particularly pointed, should be avoided ; otherwise there is a danger
of puncturing the parietal pleura, which may be intact. Exploration can
best be made with thoroughly cleansed fingers. Careful percussion will
usually enable pneumothorax or hydrothorax to be detected. In cases of
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84          THE SURGICAL ANATOMY OF THE HORSE
septic pleurisy the temperature becomes rapidly elevated. Injury to the
lungs is usually associated with a blood-tinged discharge from the nostrils.
Where there is any doubt, it is best perhaps to treat as though the wound
is a penetrating one, and in all such cases the prognosis given should be
unfavourable ; for very small punctures, such as are sometimes produced by
the prong of a fork, may quickly produce a fatal result.
Treatment should follow general principles. Wounds which are
known not to penetrate the wall should be thoroughly examined and
cleansed, all foreign matter being removed. Free drainage must be
provided in the case of deep wounds extending downwards and backwards
at the front of the chest, to prevent the formation of a fistula. For this
purpose it is frequently necessary to make a counter dependent opening.
Large gaping wounds should be packed with tow or cotton-wool saturated
with antiseptics, and all haemorrhage arrested by ligaturing ruptured or
damaged vessels. When secondary haemorrhage occurs, cold applications
should be utilized.
In wounds which penetrate the thorax, any damaged vessels should be
immediately ligatured, the wound should be thoroughly disinfected, and
efforts made to promote healing by first intention. Over the usual dress-
ings a pad is applied, and kept in position by a bandage passed around
the body or by means of the roller.
SHOULDER ABSCESS OR SHOULDER TUMOUR
It will be remembered that the mastoido-humeralis muscle descends
the neck, and passes over the front of the shoulder to run to its insertion
into the ridge descending from the external tubercle of the humerus. As
it passes over the shoulder it spreads out and becomes much thinner.
In draught horses we frequently encounter a large swelling which is
developed either in the muscle near the front of the shoulder or below it,
and which occasionally extends to the front of the chest above the anterior
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SHOULDER ABSCESS OR SHOULDER TUMOUR 85
extremity of the cariniform cartilage of the sternum. To this swelling the
name shoulder abscess or shoulder tumour is given.
In the early stages the swelling is hard and well-defined, and is but
slightly painful to the touch. It rarely causes lameness, and the skin
covering the growth is usually found to be quite sound, and is not inti-
mately adherent to the underlying tissues.
The swelling always contains pus, and the presence of pyogenic cocci
can invariably be demonstrated. As the condition progresses, the growth
becomes harder, the abscess cavity gradually diminishes, and its walls
thicken, so that the enlargement presents a tumour-like appearance.
Many different explanations have been offered as to the manner in
which the organisms gain access to the part. It is unreasonable to assume
that they are admitted through a wound or other such injury to the part,
owing to the condition in which the skin is found. Some observers,
including Franck, have associated the affection with injury to the
prescapular lymphatic glands, which, it will be remembered, are in close
proximity. Others have reported the occurrence of the tumour as a sequel
to infection of the foot and lower part of the limb, maintaining that in
these cases the pus-producing organisms are conveyed to the seat of
formation of the abscess by the lymph stream. The appearance of the
swelling has also been observed in cases of strangles. This is probably an
accidental circumstance, since the affection is almost exclusively confined
to draught horses. Most frequently, however, it is attributed to injury to
the parts beneath the skin of this region produced by a badly-fitting
collar.
The growth increases in size very slowly, and an animal may work for
a considerable length of time without experiencing much inconvenience,
and especially so if the pressure of the collar over the seat of the growth
be relieved by removing some of the padding.
There are many methods of treating the affection, such as blistering,
puncturing the abscess and curetting its walls, internal administration of
iodide of potassium, etc. But the best method is to excise the growth.
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86          THE SURGICAL ANATOMY OF THE HORSE
If the growth be very large, its size may be considerably reduced, and the
operation of excision thereby facilitated, by the frequent internal adminis-
tration of small doses of iodide of potassium.
The animal should be cast on the healthy side, and the operation area
thoroughly cleansed, the hair being removed. A number of pairs of
artery forceps should be at hand, as there is usually a considerable amount
of haemorrhage. The cutaneous incision is made downwards and back-
wards over the middle line of the tumour, care being taken to limit the
incision to the skin. As has already been stated, the skin is but loosely
applied to the subjacent structures (should any portion of it be firmly
attached, this part should be removed). Dissection is thus easy, and the
free edges of the skin are drawn apart. A piece of stout tape is now
passed through the growth by means of a needle. By means of this the
operator is enabled to exert traction on the tumour. The subsequent pro-
cedure is very similar to that adopted in excising an elbow tumour (see
Vol. II.). During dissection care must be taken not to make an incision
into the tumour, as this would give rise to a considerable amount of
unnecessary haemorrhage. Keeping strictly to the limits of the growth,
the connective tissue can frequently be broken down with the fingers. It
is best to work first to the inner side of the growth, and then below it.
During this stage care must be taken to avoid the inferior cervical artery
and the carotid and its branches. The former, it will be remembered,
splits into two divisions, one of which ascends the neck, whilst the other
descends in the groove between the mastoido-humeralis and the anterior
division of the pectoral muscle alongside the cephalic vein. Whilst
breaking down the connective tissue, vessels which feed the tumour will
be encountered. These are frequently of considerable size. To each of
these two ligatures should be applied, and the vessel severed between them.
The tumour, firmly seized by means of the tape, is now removed. Tha
haemorrhage is arrested by ligaturing the gaping ends of any vessels, and
the cavity is washed out with antiseptic solution. It is then plugged with
antiseptic tow or cotton-wool, and the edges of the skin are brought
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THE BACK AND WITHERS
87
together by means of two or three loosely-inserted sutures to hold the
plug in position. Finally the part is dusted over with dry dressing and
the animal allowed to rise. Next day the sutures should be cut, the plug
removed, and the cavity dressed. A fresh plug is introduced, and held in
position as before. After repeating this process three or four times, all
that is necessary is to keep the wound clean and apply dry dressings
frequently, allowing the cavity to heal up by the ordinary process from
the bottom. Granulation tissue quickly forms, and after a period varying
from three to four weeks the surface of the wound is level with the
surrounding skin, and is covered by a thin dry pellicle.
THE BACK AND WITHERS
In Plate IX. we have represented a transverse vertical section across
the anterior third of the dorsal region. It is of interest inasmuch as it
represents the parts as they are superposed one to the other in the region
which in the working animal is subjected to considerable pressure—in the
riding animal by means of the saddle, and in the draught animal by the
pad or saddle of the harness or gears. In the centre of the Plate is the
body of a dorsal vertebra which is pierced by the neural canal containing
the spinal cord. Extending upwards from the body is the neural spine,
the great height of which in this region is apparent. At the tip of the
spine is the supraspinous ligament, which at the summit of the spine of
the fourth dorsal vertebra becomes continuous with the funicular division
of the ligamentum nuchas. The scapula and its cartilage of prolongation
are clothed by muscle on either side. In the costo-vertebral groove on
either side there is a bed of muscular tissue composed chiefly of .the
longissimus dorsi, latissimus dorsi, dorsal portion of the rhomboideus,
dorsal trapezius, and the semispinalis muscles. The scapular fascia, which
binds down the supraspinatus and infraspinatus muscles on the dorsum
of the scapula, and which is firmly attached to the scapular spine, extends
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88           THE SURGICAL ANATOMY OF THE HORSE
upwards over the outer surface of this bed of muscle as a dense tough
sheet, to blend superiorly with the supraspinous ligament. Superposed
to this is the fascia of the dorsal portion of the panniculus carnosus.
It is loosely connected with the scapular fascia, and during the process
of dissection is easily separated. Covering the whole, again, is the skin
and subcutaneous fascia.
SADDLE GALLS
These are swellings which are frequently found on the area upon
which the saddle rests. They are sometimes firm and well-defined, in
which cases the injury is almost entirely confined to the skin. Occasion-
ally they are ill-defined, and are soft and fluctuating when the extrav-
asation of blood and lymph is into the loose subcutaneous fascia.
The condition is due to bruising of the part by a badly-fitting
saddle, the surface of which does not respond accurately to the surface
of the body upon which it rests, with the result that there is abnormal
compression of some parts, which damages the blood-vessels and lymphatics.
When the pressure is relieved by removing the saddle, extravasation
quickly occurs, leading to the formation of the swellings referred to. It
will be observed from the Plate that bruising of the skin covering the tips
of the superior spinous processes very readily occurs, since there is no
underlying muscular tissue to give elasticity to the part. In these cases
the swelling is diffused. They are frequently due to injury by the
pummel or abnormal pressure through insufficient pannelling. The
swellings vary in size. Some are no larger than a shilling. Others,
again, appear as large more or less circular patches with flattened surfaces.
Their presence is best detected by passing the palm of the hand gently
over the region.
When the condition is confined to the skin, and there is not a great
amount of extravasation, the latter may quickly become reabsorbed and
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SADDLE GALLS                                        89
the swelling disappear. If more deeply seated, they last for a much
longer period.
A common sequel in cases which do not receive proper attention is
necrosis of a small area of skin and the formation of what is known as
a "sitfast."
It will be evident, from what we have said, that to prevent the
formation of galls it is advisable not to remove the pressure on the part
too suddenly. For this reason the saddle is allowed to remain in position
for about an hour after the animal has been stabled, thus allowing the
circulation of the part to be gradually restored.
If the gall is present, and the case is seen immediately after its
formation, cold applications are indicated, as they prevent an extension
of the extravasation. Gentle massage with the hand assists reabsorption.
Next day moist warm applications should be utilized and the massage
continued.
In cases of " sitfast," hot fomentations, poultices, etc., are frequently
adopted to hasten separation and sloughing of the necrosed part. But
the most effective method of dealing with them is to dissect out the dead
tissue, the knife passing through the zone of healthy tissue surrounding
it, and subsequently to treat the wound in the ordinary way with dry
antiseptic dressings.
FISTULOUS WITHERS
This is the term commonly applied to a tubular ulcer in the region
of the withers. Strictly speaking, however, the condition is usually a
sinus opening on to the cutaneous surface. A true fistula may be formed
when there is a communication between the cutaneous surfaces of both
sides, or when the tube extends into a joint (e.g., costo-central or inter-
vertebral), conditions which are met with in rare cases. The condition
may arise as a sequel to a suppurating gall, or it may be due to some
more deeply seated injury, such as fracture of portions of the vertebras,
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go           THE SURGICAL ANATOMY OF THE HORSE
injury to and necrosis of ligament, etc. The nature and course of the
affection are very similar to those associated with a sinus of the poll
(Poll Evil, see Vol. I.), but the withers is a very much more favourable
seat for operating, and adequate drainage is more easily procured. This
will be readily appreciated if a reference be made to the two figures
indicating vertical sections through the two seats.
Treatment is on the ordinary lines, as in poll evil—namely, to open
up the sinus to its depth and remove any diseased tissue which is operating
as a foreign body. It will be observed that one can operate with much
greater freedom at the withers, owing to the great depth of muscular
tissue here. Several arterial branches will be encountered; these are
derived chiefly from the dorsal artery. Haemorrhage from them should
be arrested by compression with artery forceps. The wall of the sinus
should be removed with the curette, and, if necessary, adventitious fibrous
tissue sliced away.
When the sinus is of great depth, it will often be found effective, in
producing adequate drainage, if the withers be pierced and a seton tape
led out at the other side. Consecutive treatment is similar to that already
described in Vol. I. when dealing with poll evil.
THE BONES—FRACTURES
The Dorsal Vertebra
Of these there are eighteen in the horse. The centrum is shorter
than in any other region. Its anterior extremity is convex, but less
so than in the cervical region. Correspondingly, its posterior end
is more shallow. One of the characteristic features of this series is
the presence at each end of the body, and on either side, of a small
concave facet. This forms, with the facet on the adjacent vertebra and
the intervertebral substance, a cup-like cavity for the reception of the
head of a rib in the formation of a costo-central joint. Anterior and
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THE BONES—FRACTURES
91
posterior notches are present, the posterior being the deeper. In the last
few members the latter are frequently converted into foramina. The
oblique or articular processes are very small, as are also the transverse
processes. The latter are undivided, and each carries a small flattened
facet for articulation with the tubercle of a rib. The neural ring is
transversely elliptical. But the most striking feature of these vertebrae
is the enormous size of the superior spinous process. Each of these is
flattened from side to side. Its posterior edge is thicker than the anterior,
and the former is also grooved. The inferior spine is simply represented
by a faint ridge.
The height of the superior spinous processes varies in the different
members. It is greatest in the fourth, from which its height diminishes
as we proceed forwards and backwards. The spine of the second vertebra
is broader than that of the first. From the second to the tenth the breadth
diminishes, and then progressively increases again from the tenth to the
eighteenth. In most of the vertebrae the summits of the spines are rough
and tuberous. In others they are smooth and compressed from side to
side. The sixteenth spine is disposed vertically. Those in front of it
incline slightly backwards, and those behind slightly forwards.
The first dorsal vertebra bears a close resemblance to the last member
of the cervical series. Its superior spine has a height of about three
inches only, and its summit is pointed. Its remaining processes and the
notches in the arch are relatively large. There is no posterior capitular
facet on the body of the eighteenth vertebra. With the exception of the
transverse processes, the last few members of the dorsal series bear a close
resemblance to those of the lumbar region.
A close examination reveals a tendency to division of the transverse
processes. This tendency is accentuated as we proceed from the first
member backwards, and in the last three or four bones it is complete, the
inner portion being found above the anterior oblique process and corre-
sponding to the mammillary process of the human subject, and the outer
portion carrying the facet which articulates with the tubercle of the rib.
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92           THE SURGICAL ANATOMY OF THE HORSE
There are several minor points in connection with these bones, which,
however, do not concern us here.
Fractures of the dorsal vertebras in the horse are not uncommon.
The transverse and oblique processes are very small, and are well protected
by the mass of muscle lying in the costo-vertebral groove. The bodies
are also afforded similarly a considerable degree of protection. Consequently
the same causes of fracture as operate in most other regions, such as blows
received over the part, are generally less effective here. But the tips of
the superior spines are particularly exposed, and are not uncommonly
broken off. The spines which are most exposed are the highest—namely,
those in the region of the withers. Thus we find portions broken off
and displaced, leading to the formation of fistulous withers. Colliery
ponies are particularly predisposed to fractures of this type, through
catching the part in transverse beams which support the roof in places
where the latter is low. In these ponies, also, crushing of the arches and
bodies of the vertebra? is common as a result of falls of the roofs; but it
will be conceded that the risks run in these cases are extraordinary.
Fracture may also be due to the animal's coming over on its back when
rearing, whilst it may be the result of a violent collision. It is said, too,
to result from starting or stopping too suddenly.
But the most frequent cause of fracture of the vertebras is violent
muscular contraction in jumping or in struggling after casting. When
the longissimus dorsi is relaxed the muzzle can be drawn readily towards
the breast. A sudden and violent contraction of this great muscle would
then throw enormous pressure on one vertebra, particularly towards the end
of the dorsal series, the pressure being frequently so great as to crush the
bone into several pieces. Thus we have a comminuted fracture. The
bringing of the muzzle towards the chest, arching of the back, and sudden
violent contractions of the longissimus dorsi, can be observed in any spirited
horse when he is cast for operation, unless steps have been taken to prevent
them. Thus fractured vertebra is most commonly a complication when an
animal is cast for the purpose of performing an operation, and the fracture
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THE BONES—FRACTURES
93
is not due to the fall, but to the struggling of the animal to release
itself.
Should there be no displacement or serious rupture of the ligaments,
it is possible for a fracture to occur and for the parts to reunite without
any symptoms being presented which call particular attention to the case.
Post-mortem examination of bones reveals the fact that such cases are by
no means rare. In them the ligaments have maintained the parts in
position and prevented displacement, thus avoiding any undue pressure
upon the spinal cord.
Fracture is predisposed in cases of anchylosis of vertebras, ,and also in
old animals and others where the bones are abnormally brittle. This is
owing to the diminished elasticity of the part.
Excessive contraction of the muscles of one side, which act in curving
the spine, may also bring about fracture of the vertebras or their oblique
processes.
It will be readily understood that the muscles concerned can by their
contraction throw much more pressure upon the vertebras towards the
middle of the spine if the animal be on its side than if it be placed on its
back, for in the former position much greater freedom is afforded them.
Consequently, as Moller and DieckerhofF pointed out, fracture whilst the
animal is lying on its back is rare.
According to W. Williams, fractured vertebra was in his day
much more common in Scotland than in England, and he attributed it to
the Scotch method of securing the animal when cast so as to prevent
movement of the limbs.
In cases of fractured superior spines at the withers, the fractured
pieces can sometimes be felt if the case be seen early and before much
swelling has appeared. There is an alteration in the conformation, which
is lowered, for the fractured pieces are usually displaced in the downward
direction. There is also interference with the muscles acting on the fore
limb, which are attached to these processes, so that the animal may go
lame.
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96          THE SURGICAL ANATOMY OF THE HORSE
the thorax, and is clothed by the parietal layer of the pleura. The
anterior border is curved, with the concavity directed forwards. It is thin
and sharp. The posterior border is much thicker. It is convex and
rough, and presents a groove for the accommodation of the intercostal
vessels and nerve, which is most pronounced in the upper half of the
bone. The inferior extremity is irregularly excavated for the reception of
the upper end of the corresponding costal cartilage. Where the body
presents its greatest degree of curvature we have what is known as the
angle of the rib.
A rib develops from one principal centre of ossification for the body,
and two supplementary centres for the head and tubercle respectively. It
contains a large proportion of spongy tissue, particularly in its inferior
third, and this affords the bone a considerable degree of elasticity.
A typical costal cartilage is a somewhat cylindrical rod slightly com-
pressed from side to side; at its upper end it is received into the cavity,
already described, on the lower extremity of the rib, and forms with the
rib an obtuse angle. Its inferior end is either tapering to a blunt
extremity or in the form of an enlargement carrying an articular surface.
The latter are the cartilages of the sternal ribs, which numerically are the
first eight. The former are the terminations of the asternal or false ribs.
The cartilage of each asternal rib is attached to that of its predecessor in
the series. That of the ninth rib is intimately attached to the eighth or
last sternal rib. The cartilages of the second to the eighth sternal ribs
articulate with facets, to be described, on the lateral surface of the
sternum, whilst the cartilages of the first pair of ribs articulate one
with the other in the notch on the superior border of the presternal
cartilage.
The length of the ribs and cartilages increases progressively from the
first to the ninth, and then progressively decreases to the eighteenth. The
curvature becomes more pronounced from the first to the last; the breadth
of the body increases from the first to the sixth, and then progressively
diminishes to the end of the series.
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THE BONES—FRACTURES                              97
The first rib has special characters, which have been described when
dealing with this bone in Vol. II.
Fracture of the first rib is one of the greatest importance and intense
interest to the surgeon, since it usually produces a peculiar lameness
associated with characteristic symptoms in the fore limb. The condition
has been treated at length in Vol. II. (pp. 146-151).
With regard to the remaining ribs, the second to the sixth are well
protected by the scapula and humerus, with the enormous muscular mass
found in the angle formed between them. But the remaining ribs are
particularly exposed to risk of injury, and fracture of them is common as a
result of blows or kicks, collision with the extremities of shafts or carriage
poles, falling on hard, uneven ground, crushing between the tubs and wall
of the passage in collieries, etc. The fracture may be simple (in young
animals partial fractures where the bone has simply been bent inwards
have been observed) or compound, and may lead in the case of the
majority of the ribs to septic pleurisy. Occasionally serious injury
is inflicted on the lung by the jagged fractured ends, and even on the
heart.
Remembering the line of attachment of the diaphragm and the
concavity of its abdominal surface, fracture and displacement of the
posterior ribs may lead to serious injury to structures in the abdominal
cavity, in illustration of which we have the case of Groswend's, in which,
the last rib being fractured, the omentum and stomach were pierced by
the displaced portions. The diaphragm is frequently punctured or
lacerated.
But an examination of skeletons reveals the fact that ribs are very
frequently fractured, and the fracture repaired, without any suspicion having
been drawn to the case during life.
It will thus be seen that cases vary from those which are so simple as
not to attract any particular attention, to cases of extreme gravity with
such complications as septic pleurisy or peritonitis, or laceration of some
large blood-vessel, with fatal internal haemorrhage. In considering the
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96          THE SURGICAL ANATOMY OF THE HORSE
the thorax, and is clothed by the parietal layer of the pleura. The
anterior border is curved, with the concavity directed forwards. It is thin
and sharp. The posterior border is much thicker. It is convex and
rough, and presents a groove for the accommodation of the intercostal
vessels and nerve, which is most pronounced in the upper half of the
bone. The inferior extremity is irregularly excavated for the reception of
the upper end of the corresponding costal cartilage. Where the body
presents its greatest degree of curvature we have what is known as the
angle of the rib.
A rib develops from one principal centre of ossification for the body,
and two supplementary centres for the head and tubercle respectively. It
contains a large proportion of spongy tissue, particularly in its inferior
third, and this affords the bone a considerable degree of elasticity.
A typical costal cartilage is a somewhat cylindrical rod slightly com-
pressed from side to side; at its upper end it is received into the cavity,
already described, on the lower extremity of the rib, and forms with the
rib an obtuse angle. Its inferior end is either tapering to a blunt
extremity or in the form of an enlargement carrying an articular surface.
The latter are the cartilages of the sternal ribs, which numerically are the
first eight. The former are the terminations of the asternal or false ribs.
The cartilage of each asternal rib is attached to that of its predecessor in
the series. That of the ninth rib is intimately attached to the eighth or
last sternal rib. The cartilages of the second to the eighth sternal ribs
articulate with facets, to be described, on the lateral surface of the
sternum, whilst the cartilages of the first pair of ribs articulate one
with the other in the notch on the superior border of the presternal
cartilage.
The length of the ribs and cartilages increases progressively from the
first to the ninth, and then progressively decreases to the eighteenth. The
curvature becomes more pronounced from the first to the last; the breadth
of the body increases from the first to the sixth, and then progressively
diminishes to the end of the series.
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THE BONES—FRACTURES
97
The first rib has special characters, which have been described when
dealing with this bone in Vol. II.
Fracture of the first rib is one of the greatest importance and intense
interest to the surgeon, since it usually produces a peculiar lameness
associated with characteristic symptoms in the fore limb. The condition
has been treated at length in Vol. II. (pp. 146-151).
With regard to the remaining ribs, the second to the sixth are well
protected by the scapula and humerus, with the enormous muscular mass
found in the angle formed between them. But the remaining ribs are
particularly exposed to risk of injury, and fracture of them is common as a
result of blows or kicks, collision with the extremities of shafts or carriage
poles, falling on hard, uneven ground, crushing between the tubs and wall
of the passage in collieries, etc. The fracture may be simple (in young
animals partial fractures where the bone has simply been bent inwards
have been observed) or compound, and may lead in the case of the
majority of the ribs to septic pleurisy. Occasionally serious injury
is inflicted on the lung by the jagged fractured ends, and even on the
heart.
Remembering the line of attachment of the diaphragm and the
concavity of its abdominal surface, fracture and displacement of the
posterior ribs may lead to serious injury to structures in the abdominal
cavity, in illustration of which we have the case of Groswend's, in which,
the last rib being fractured, the omentum and stomach were pierced by
the displaced portions. The diaphragm is frequently punctured or
lacerated.
But an examination of skeletons reveals the fact that ribs are very
frequently fractured, and the fracture repaired, without any suspicion having
been drawn to the case during life.
It will thus be seen that cases vary from those which are so simple as
not to attract any particular attention, to cases of extreme gravity with
such complications as septic pleurisy or peritonitis, or laceration of some
large blood-vessel, with fatal internal haemorrhage. In considering the
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98          THE SURGICAL ANATOMY OF THE HORSE
latter complication, it is well to remember the courses taken by the inter-
costal and internal thoracic arteries, as these are the vessels most frequently
involved. Where the first few members of the series are fractured,
laceration of the still larger vessels near the entrance to the thorax may
complicate the case.
If the lung be injured, there is frequently a blood-tinged discharge
from the nostrils. In pleurisy the breathing is hurried, and there is
frequent coughing. Palpation does not render much assistance unless
the fracture affects one of the posterior members, and the case be seen
early, before there is much swelling of the muscular layers covering the
ribs. If the fracture be compound, diagnosis is of course easier, since a
finger thoroughly cleansed may be introduced carefully into the wound.
It is most difficult to reduce fractures of ribs. The animal should be
kept quiet, and movement of the part limited as much as possible. With
the latter object Williams applied a belt around the body. In compound
fractures, antiseptic dressings should be applied and the wound closed to
guard against septic infection.
SINUS OF THE CHEST WALL
This is a chronic condition, and is usually due to necrosis of one or
more ribs as a result of external injury. Occasionally it is a burrowing
downwards of purulent material in cases of fistulous withers. The
necrosed tissue acts as a foreign body, irritating the surrounding healthy
parts and setting up chronic inflammation. The surrounding tissues
become thickened, and much adventitious fibrous tissue is formed. There
is in consequence little tendency to perforation into the pleural sac and
septic pleurisy. The pus burrows outwards, and we have an opening on
the exterior from which there is a chronic offensive discharge.
Efforts should first be made to ascertain the position of the diseased
bone by searching the depths of the sinus with a probe. It may be
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THE STERNUM—FRACTURE AND OTHER INJURIES 99
necessary to enlarge the cutaneous opening to facilitate drainage. If there
be a loose piece it should be removed; otherwise the area should be
carefully curetted, together with the walls of the sinus, which should
afterwards be washed out with antiseptic solutions in the ordinary manner.
When the sinus opens into the pleural sac the case is usually hopeless.
THE STERNUM—FRACTURE AND OTHER INJURIES
This is sometimes referred to as the haemal spine. It is placed at
the floor of the thorax, and is partly osseous and partly cartilaginous in
structure.
It presents three surfaces, three borders, and two extremities. The
superior face is in the form of a much-elongated isoceles triangle, the
apex of which is directed forwards. This surface forms the floor of
the thorax, and is slightly concave in the longitudinal direction. Its
inclination is obliquely downwards and backwards.
The lateral surfaces incline obliquely downwards and inwards to the
middle line, where they meet at the inferior border. Each presents
superiorly seven articular areas, which are slightly depressed for the
reception of the extremities of the costal cartilages in the formation of
the chondro-sternal joints. The first four depressions are widely separated,
and elongated from above to below. The last three are more circular
and closer together. The remainder of each lateral surface is roughened
for the attachment of the pectoral muscles.
Along each border separating the superior and lateral surfaces, runs
a fibrous cord. These borders meet anteriorly.
Attached to the front of the bone is the presternal or cariniform
cartilage. This is a plate compressed from side to side. Its inferior
border is convex, and is continuous with the inferior border of the
sternum itself, which border is also largely cartilaginous. Its superior
edge presents a deep notch in which the cartilages of the first pair of ribs
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ioo THE SURGICAL ANATOMY OF THE HORSE
meet, as already stated. Its anterior end is curved and free, and in many
cases can be felt in the living animal. Attached to the last segment of
the bone is the ensiform or xiphoid cartilage. This is also plate-like,
and is flattened from above to below. It is usually referred to as bearing
in outline a semblance to the heart of playing-cards. Its superior
surface is very slightly concave, and that portion behind the line of
attachment of the diaphragm forms part of the floor of the abdomen.
In the horse the sternum is particularly well protected, in marked
contrast to the corresponding bone in the human subject. It is extremely
well clothed by the thick muscles at the front of the chest, so that fracture
in the horse is very rare. It can only occur as a result of a very severe
injury, and is usually accompanied by fatal internal haemorrhage through
laceration of the internal thoracic arteries. These, it will be remembered,
pass underneath the triangularis sterni muscle on the floor of the thorax,
and in close apposition to the bone. Their position is so inaccessible that
practically nothing can be done to arrest haemorrhage from them, even if
the case be successfully diagnosed.
Notwithstanding what we have said regarding actual fracture of the
sternum, the bone is frequently damaged, and a sinus opening at the front
of the chest as a result of a deeply-seated diseased portion of the sternum
is a common occurrence. The depth of muscular tissue provides an
excellent medium for the burrowing of purulent material for a consider-
able length of time without attracting attention, and in directions which
are sometimes very deceptive.
Occasionally the anterior portion of the bone is involved in pene-
trating wounds at the front of the chest received during collisions. In
colliery practice these are probably most common, owing to low-lying
obstacles which are frequently encountered. Or such a wound may
result from the animal alighting on a stake when attempting to negotiate
a fence. The posterior portion may be injured by prominent calkins or
fore shoes.
The parts between the fore limbs swell up in many cases to such
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THE JOINTS
101
a degree as to interfere markedly with the action of the limbs. After
a while multiple openings may present themselves. That the persistence
of the affection is due to an injury to the bone may be ascertained by
probing carefully, when the passage of the probe will be suddenly arrested
by a hard resistant structure at the depth of the principal sinus. The
rational treatment would be that adopted in treating sinuses generally—
namely, to lay open the sinus, curette its walls, and scrape the diseased
bone, following this with antiseptic treatment of the wound, which is
allowed to heal from the bottom. The destruction of the walls by means
of the introduction of the actual cautery has been frequently practised.
The sinuses, however, are of the most persistent nature, the anatomy of
the parts being distinctly favourable to their formation, as already stated.
Consequently favourable results from treatment are rare, and prognosis
should be given accordingly.
THE JOINTS
The Intervertebral Joints.—These are the joints between adjacent
vertebras. The anterior end of the centrum of one vertebra is united to
the posterior end of that immediately preceding it through the medium
of the intervertebral substance, thus forming an amphiarthrodial joint.
This substance is a disc of fibro-cartilage, convex on its anterior aspect,
and concave posteriorly. In the dorsal region the discs are not so thick
as in the cervical and lumbar regions, and in this region they assist
in forming the cup-like cavities which receive the heads of the ribs.
Towards its centre each disc is soft and pulpy. Its periphery is thicker,
and is made up of fibrous tissue and fibro-cartilage in alternating layers.
The periphery unites the adjacent vertebrae, and the nature of the central
portion enables the bones to move one on the other.
The ligaments uniting the bones in a typical intervertebral joint
(e.g., between the fourteenth and fifteenth dorsal vertebrae) are as follows:
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io2 THE SURGICAL ANATOMY OF THE HORSE
Supraspinous Ligament.—As its name implies, this runs along the tips
of the superior spinous processes. It is in the form of a thick and
powerful cord which runs from the summits of the sacral spines to the
spine of the fourth dorsal vertebra, where it becomes continuous with the
funicular division of the ligamentum nucha?. This ligament is frequently
involved in cases of fistulous withers, when portions of it have to be
excised.
Inter spinous Ligaments.—These fill the spaces between the superior
spines. Each ligament consists of two small flat sheets closely applied to
one another. The fibres run obliquely downwards and backwards, and
thus permit the separation of the spines when the back is arched.
Ligamenta Subflava.—These connect the edges of the arches of
adjacent vertebra.
Inferior Common Ligament.—This runs along the inferior aspect of the
centra and intervertebral discs. It is represented by a thin layer of fibres,
and some may be traced on the inferior aspect of the sacrum. As a
distinct band, however, the ligament terminates at the sixth or seventh
dorsal centrum where the longus colli begins. This replaces the inferior
common ligament in the neck.
Superior Common Ligament.—This ligament runs along the floor of the
neural canal on the superior surfaces of the centra, to which it is closely
adherent. It also adheres to the interarticular ligaments of the costo-
central joints and to the superior borders of the intervertebral discs. As
it passes over each disc its breadth increases. Posteriorly it extends to
the coccygeal region, whilst anteriorly it becomes continuous with the
odontoid ligament of the atlanto-axial joint.
The anterior pair of oblique processes of one vertebra articulate with
the posterior pair of oblique processes on the immediately preceding bone,
forming diarthrodial joints. Each of these joints is provided with a small
capsular ligament which is attached around the margins of the articular
surfaces of the two processes which come into apposition, and which is
lined internally by a synovial membrane.
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THE JOINTS                                          103
The joints between the vertebra? of this region are capable of flexion,
extension, and rotation. They may also be curved laterally.
The height of the superior spines and the thin intervertebral discs
restrict flexion and extension, so that they are not so freely performed as in
the cervical region.
The Costo-Central Joints.—Each of these is formed by the articula-
tion of the head of a rib with the cup-like facet formed by two adjacent
vertebras and the intervertebral disc. Its ligaments are—
The Interarticular Ligament, which is attached in the roughened depres-
sion on the head of the rib, from whence it passes on to the upper border of
the intervertebral disc, to which it is also attached. In the middle line it
becomes continuous with the corresponding ligament of the opposite side.
The superior common ligament passes over it. It is not present in the first
costo-central joint.
The Costo-Vertebral or Stellate Ligament.—This arises from the rib just
below its articular head. Its fibres spread out and become attached to the
bodies of the two vertebra; concerned in the formation of the joint, and to
the intervening disc. This ligament is thus below the articulation.
Each costo-central joint, with the exception of the first, possesses two
small synovial membranes, which are placed one on either side the inter-
articular ligament. The first joint has only one.
The Costo-Transverse Joints.—These are the small diarthrodial
articulations formed between the tubercles of the ribs and the transverse
processes of the vertebras. The facets on these bones have already been
described. Each joint possesses the following ligaments :
1.   Anterior Costo-Transverse.—This runs from the neck of the rib in
front of the tubercle to the inferior part of the front of the transverse
process.
2.   ^Posterior Cos to - Transverse.—This passes from the back of the
transverse process downwards and backwards over the posterior aspect of
the articulation, to be attached inferiorly to the back of the rib just below
the tubercle.
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io4 THE SURGICAL ANATOMY OF THE HORSE
With the exception of the last two or three members of the series,
each costo-transverse joint possesses a small synovial membrane, which is
supported by the two ligaments just described. The last two or three
joints are supplied by small pouches derived from the posterior membranes
of the costo-central joints.
In the Costo-Chondral Joints, which are the articulations formed
between the upper extremities of the cartilages and the depressions at the
lower ends of the ribs, assistance in binding the bones and cartilages
together is provided by the passage of the periosteum of the bone on to the
surface of the cartilage.
The Chondro-Sternal Joints.—These are formed between the carti-
lages of the sternal ribs and the lateral surface of the sternum. The cartilages
of the first pair of ribs, however, meet in the middle line and form one
joint between them. Each of the remaining sternal cartilages is articu-
lated to one of the facets described on the sternum, and the articulation is
surrounded by peripheral fibres, which form a kind of capsular ligament
which supports internally a synovial membrane. Above and below this
ligament presents thickenings which are sometimes called the superior and
inferior chondro-sternal ligaments.
Traumatic arthritis of the intervertebral and costo-vertebral joints may
arise from an extension of a sinus into them, as, for instance, in deep
sinuses of the withers. Extensive lacerated wounds at the sides of the
chest may also communicate with the chondro-sternal joints. Diagnosis
is not so readily established as in traumatic arthritis of most other joints.
Owing to the position of the articulations, the escape of synovia from the
capsule of the joint is usually not apparent, since it is either discharged
into the surrounding tissues or accumulates in one or other of the pockets
formed during the tunnelling of the sinuses.
Owing to the complexity of structure of the intervertebral and costo-
vertebral joints, and the amount of pressure which this area of the body is
required to sustain, these joints are frequently the seats of injuries which
are practically impossible to diagnose accurately during life, and their
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THE JOINTS
io5
common occurrence is effectively confirmed by examination of post-
mortem specimens. It is not difficult to conceive of the readiness
with which one or other of the numerous ligaments described may be
ruptured or lacerated during abnormally sudden and violent curvature of
the spine. From pressure on the back we may have laceration of the
superior and inferior common ligaments, and displacement of the vertebrae
forming the joint. When such displacement does not occur to a degree
which admits of abnormal pressure on the cord, the difficulty of diagnosis
is only accentuated. Similarly, the small capsular ligaments and the synovial
membranes of the joints between the oblique processes may become injured.
The result is that, from the above amongst numerous causes leading
to a chronic inflammation, anchylosis of the joints is common.
As has been stated, such affections are obscure, but to a keen observer
the presence of some injury will be suggested by the want of freedom in
the movements of the animal; he does not turn with the usual elasticity,
he backs with snatchy movements. The efforts are restricted, and it will
be apparent that in the movements in which the spine is concerned the
animal does not put its whole energy into its work. These differences
will be most apparent to one who is acquainted with the animal. Injury
to these parts is most frequently encountered in animals which are
energetic, nery workers.
Little can be done. If injury is suspected, palpation of the part may
produce evidence of pain if the case be seen in the early stages. Too
much reliance, however, must not be placed upon this, since most animals
will flinch if the points of the fingers be applied to the back, even with
slight pressure. Variations in cutaneous temperature are of little assistance,
owing to the depth of muscle between the skin and joints. If the case
be suspicious, no harm can be done, and considerable relief frequently
afforded, by hot applications to the back, followed by a liniment.
The condition, however, usually runs a chronic course, leading to
anchylosis of one or more of the joints, though the animal may work
regularly for the rest of its life.
o
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CHAPTER III
THE ABDOMEN, LOINS, ETC.
The cavity of the abdomen is much the largest of the body cavities. It
is placed behind the thorax and in front of the cavity of the pelvis.
From the thoracic cavity it is separated by the diaphragm. Posteriorly
it passes insensibly into the pelvic cavity, for there is no partition between
them. The brim of the pelvis, the anterior border of the sacrum, and
the ileo-pectineal line, are, however, generally regarded as forming the
line of division between the two chambers.
In form it is somewhat ovoid, but slightly compressed from side to
side. Its longest dimension extends from the centre of the attachment
of the diaphragm to the • sternum, backwards to the middle of the
entrance to the pelvis. Its greatest vertical dimension would be
indicated by a line drawn perpendicular to the body of the first lumbar
vertebra.
Superiorly the cavity is bounded by the lumbar vertebrae and the
sublumbar muscles, together with the upper portion of the diaphragm.
Its floor is made up of the xiphoid cartilage of the sternum, the two
straight abdominal muscles, the aponeuroses of the four oblique and
two transverse abdominal muscles, and the abdominal tunic. Laterally
it is bounded by the oblique and transverse abdominal muscles, the
abdominal tunic, the cartilages of the asternal ribs, those parts of the
posterior ribs which are behind the attachment of the diaphragm, and
parts of the iliac segments of the pelvis.
Three apertures pierce the diaphragm, as already described. In
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THE ABDOMINAL WALL                             107
addition the abdominal wall is pierced by the two inguinal canals, and in
the foetus also by the umbilical opening.
The contents of the cavity include the digestive and the greater part
of the urinarv apparatus, part of the internal generative organs, together
with numerous nerves, blood and lymph vessels, and glands.
THE ABDOMINAL WALL
The sides and floor of the abdominal wall are made up chiefly of
muscle.
If the subject be placed on its back and the skin reflected, the
panniculus carnosus and the abdominal tunic are exposed, whilst
anteriorly the posterior broad portion of the posterior deep pectoral
muscle is seen.
The Panniculus Carnosus is a thin sheet spread over part of the
abdominal wall, and extending over the thorax on to the shoulder. It
does not extend posteriorly on to the hind limb, but may be said to
commence in the loose fold at the flank, from whence its superior border
extends upwards and forwards to near the superior dorsal spines, whilst
its inferior border runs downwards and forwards to an angle placed from
five to six inches from the puckered cicatrix-looking body known as the
umbilicus. From this latter angle the inferior border runs upwards and
and forwards in the direction of the elbow. It sends a thin tendon
forwards between the chest wall and the fore limb, to be attached to
the internal tuberosity of the humerus. Superiorly the aponeurosis of this
muscle is attached to the spines of the vertebras. For a great extent the
deep face is intimately adherent to the abdominal tunic. By the action
of this muscle the animal is enabled to twitch the skin.
The Abdominal 'Tunic is a sheet of tough yellow elastic tissue. It is
spread over the floor and sides of the abdomen. It is thickest near the
middle line and posteriorly. Tracing it forwards, it will be found to pass
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108 THE SURGICAL ANATOMY OF THE HORSE
beneath the posterior deep pectoral muscle. Outwardly it extends over
the muscular portion of the external oblique muscle, and becomes very
much thinner. The tunic assists the muscles to support the abdominal
viscera, and acts as a natural elastic bandage. Posteriorly it detaches two
slips, which are known as the suspensory ligaments of the prepuce.
The Obliquus Abdominis Externus.—Having removed the abdominal
tunic, this muscle is exposed. Its muscular portion, which is placed
superiorly, arises from the outer surfaces of the last fourteen ribs and from
the tendon of the latissimus dorsi muscle. This is succeeded by a large
expanded aponeurotic tendon which is inserted into the linea alba, the
external angle of the ilium, and the prepubic tendon. The direction
taken by its fibres is obliquely downwards and backwards. Between the
prepubic tendon and the angle of the haunch the fibres of the tendon curve
upwards and forwards, forming what is known as Poupart's ligament, which
forms one of the boundaries of the inguinal canal.
The Obliquus Abdominis Internus.—This muscle is deeply seated to the
preceding muscle. Its fleshy portion arises from the external angle of the
ilium and the outer part of Poupart's ligament. The fibres run obliquely
downwards and forwards. The muscle expands as it descends, so that its
fleshy portion is fan-shaped and its aponeurotic tendon is spread out over the
inferior portion of the abdominal wall. It is inserted into the prepubic
tendon, the linea alba, and into the cartilages of the last five ribs.
It will thus be seen that the thickness of the abdominal wall in the
region of the flank is mainly formed by the fleshy division of this muscle,
a point to be remembered when performing an operation, to be described
hereafter, in this situation.
The Rectus Abdominis.—The anterior end of this muscle can be seen
before removing the internal oblique ; but when the tendon of the latter is
dissected away, the whole of the rectus is revealed. It is in the form of a
band, which is broadest in its middle third, and which runs longitudinally
along the floor of the abdomen to the side of the middle line. Here the
two recti muscles are separated only by the linea alba. It arises from the
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THE ABDOMINAL WALL
109
inferior aspect of the sternum and from the cartilages of the fifth to the
ninth ribs. By means of the prepubic tendon it is inserted into the
anterior border of the pubic bone. This muscle is easily recognized by
the fact that its substance is crossed by a number of white tendinous
intersections, forming what are known as the lines transversa?. The
thickness of the abdominal floor is mainly due to the two recti muscles.
The Transversalis Abdominis.—This is the most deeply seated of the
muscles of the abdominal wall. From the name it will be understood that
its fibres run transversely. Its fleshy portion, which is placed superiorly,
arises from the cartilages of the last ten ribs and from the transverse
processes of the lumbar vertebras. This portion is succeeded by a broad
aponeurotic tendon, which obtains insertion into the ensiform cartilage of the
sternum and into the linea alba.
The floor and sides of the abdominal wall are thus chiefly made up of
four pairs of muscles supported by a powerful elastic web, the fleshy
portions of the muscles being arranged in such manner as not to be
directly superposed one to the other.
BLOOD-VESSELS OF THE ABDOMINAL WALL
The Subcutaneous Abdominal Artery.—As its name implies, this vessel,
which is of considerable size, is placed superficially. It is found
immediately on reflecting the skin, posteriorly and quite close to the
middle line. It is one of the terminal divisions of the external pudic
artery, and may be traced forwards to the umbilicus, a little in front of
which it becomes lost. During its course it distributes branches to the
skin, the superficial inguinal lymphatic glands, to the scrotum and prepuce
in the male, and the skin covering the mammary glands in the female.
The corresponding vein runs in close company with this vessel.
Haemorrhage from this artery is common in lacerated wounds on posterior
parts of the abdominal wall.
Superficially and more outwardly placed there is another vessel,
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no THE SURGICAL ANATOMY OF THE HORSE
the course of which is plainly indicated by an upheaval of the skin in the
living animal. This is the Subcutaneous 'Thoracic or Spur Vein. It is
formed by the union of a number of small veins which drain the blood
from the skin of the flank and the region in front of the prepuce. The
vessel so formed runs forwards along a groove on the outer surface of the
panniculus muscle. Near the hinder edge of the posterior deep pectoral
muscle it pierces the panniculus, and continues its course forwards to the
axilla, where it joins the brachial vein. This vessel is commonly injured
by the spur.
A number of small branches of the intercostal arteries penetrate the
deep face of the panniculus muscle and are distributed to it.
External Pudic Artery.—This vessel may be found in the inguinal
canal. After the removal of the abdominal tunic, it will be observed
behind and slightly to the inner side of the spermatic cord. It is one
of the divisions of the prepubic artery, and it terminates by splitting into
the subcutaneous abdominal artery, already described, and the anterior
dorsal artery of the penis, which corresponds to the mammary artery
of the mare. It is accompanied by the external pudic vein. Care must
be taken to avoid this vessel when operating in the inguinal canal, and it
should be remembered that the vessel is not within the cord.
In the region of the flank a number of small arteries will be found
which are deeply seated, and are distributed to the obliquus internus and
transversalis abdominis muscles. They are derived chiefly from the
anterior division of the circumflex-iliac artery, but a few are detached
from the posterior division.
The rectus abdominis muscle is supplied by the anterior and posterior
abdominal arteries.
These vessels are deeply seated. The former is one
of the divisions of the internal thoracic artery. It may be found at the
side of the ensiform cartilage, and it runs backwards along the superior
face of the rectus abdominis muscle, giving off a number of collateral
branches. The posterior abdominal artery is the other terminal division
of the prepubic artery. Passing to the inner side of the internal abdom-
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NERVES OF THE ABDOMINAL WALL
inal ring, it runs along the deep face of the internal oblique muscle
forwards, to enter the rectus abdominis, to which it is distributed. Its
terminal branches anastomose with those of the anterior abdominal artery.
These arteries are accompanied by the corresponding veins.
NERVES OF THE ABDOMINAL WALL
A number of small nerves run down the deep face of the panniculus
muscle. They come out through the external oblique muscle, and are
perforating branches which are derived from the intercostals, from the
last dorsal nerve and the first lumbar.
Tiny filaments — branches of these perforating nerves — pass out
through the panniculus to penetrate the skin. These are very numerous
and extremely small. They are cut through when the skin is dissected
free from the panniculus.
Similar perforating branches come from the second and third lumbar
nerves. The branch of the former comes out near the angle of the
haunch, and is distributed to the skin of the anterior crural region. The
latter appears about two inches lower down, and follows the course taken
by the descending division of the circumflex-iliac artery.
"The External (or Subcutaneous) Thoracic Nerve.—This nerve comes
from the brachial plexus, and arises in common with the ulnar nerve. It
runs backwards, following the course taken by the spur vein. It dis-
tributes branches to the latissimus dorsi muscle and to the posterior
division of the deep pectoral. A number of its branches join the per-
forating branches of the intercostal nerves. Its terminal ramifications
pass to the panniculus and to the skin covering the side and floor of the
abdomen.
The last ten intercostal nerves, leaving the inferior ends of the inter-
costal spaces, continue their course downwards on the superficial face of
the transversalis abdominis muscle, and between this muscle and the rectus
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ii2 THE SURGICAL ANATOMY OF THE HORSE
abdominis. They distribute filaments to both these muscles, and other
branches which pierce the rectus abdominis from within outwards to be
distributed to the skin. The inferior primary divisions of the eighteenth
dorsal and the first and second lumbar nerves, after detaching filaments
which pass to the oblique muscles in the region of the flank, are finally
distributed in a similar manner.
INJURIES TO THE ABDOMINAL WALL
Wounds, bruises and other injuries of the abdominal wall are common.
In colliery ponies, particularly those of the larger type, the part is
frequently crushed by passing " tubs." Blood-vessels become ruptured and
otherwise damaged, with the result that a large swelling makes its appear-
ance, owing to extravasation of blood between the layers of the muscles
and sometimes also subcutaneously. At times the swelling contains pus
and is of the nature of an abscess, whilst commonly it is simply due to an
accumulation of inflammatory exudate. Wounds of the abdomen vary
from a superficial cut which may not penetrate the whole thickness of the
skin, to deep wounds which pierce the various muscular layers, and even
the parietal layer of the peritoneum. They may be caused by rough
hedges or barbed-wire fences when jumping, by the prongs of a fork, in
army horses by gun-shots, lances, bayonets, etc. The wound may be
sharply incised, but frequently the wall is extensively lacerated. In many
cases it is difficult to ascertain the exact depth of the wound owing to the
overlapping of the muscular layers, and for this reason the probe does not
provide much information.
Deep penetrating wounds of the abdominal wall of the horse were
generally regarded as being of extreme gravity, owing to the supposed
greater liability of the horse than any of the other domesticated animals to
peritonitis. Macqueen and others have in recent years shown that this
view was greatly exaggerated, and their contention is supported by the
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INJURIES TO THE ABDOMINAL WALL
manner in which the operations of ovariotomy in the female and castra-
tion of the cryptorchid male can be performed, with very little risk to the
patient, under ordinary precautions.
As will be gathered from our description of the anatomy of the part,
there will usually be a considerable amount of haemorrhage, owing to the
plentiful blood-supply, and not uncommonly vessels of considerable size
are ruptured or severed.
Treatment to a great extent depends upon the nature and degree of the
injury. In cases of swelling without penetration of the skin, care must
be taken not to confuse the enlargement with a hernia. At times they
can be readily distinguished by manipulation, particularly when the
hernia is reducible. In other cases of hernia the rupture in the
abdominal wall can be distinctly felt. Where there is any doubt, how-
ever, a searching needle should be employed.
Recent swellings as a result of crushing or bruising may frequently be
treated with advantage by cold applications. These are followed by warm
applications to promote reabsorption. Commonly, however, it is neces-
sary to open the swelling surgically and allow its contents to escape.
Should the swelling contain pus, this method should be adopted at once;
and in these cases it is frequently necessary to make a counter-opening,
owing to the manner in which the purulent material usually burrows
between the muscles. The subsequent treatment should follow the
common antiseptic lines. It is advisable, however, to keep the part as
still as possible, owing to the tendency which the wall has in such cases to
rupture, with the subsequent production of a hernia.
Those wounds are the most serious which are complicated by prolapse
of a portion of the bowel, omentum, uterus, or some other abdominal
organ. Such cases demand immediate attention. The exposed part
should be replaced at once, after cleansing it thoroughly with a warm
weak antiseptic solution. Fairly large portions of omentum may be
excised with little risk. In these cases, when the portion to be removed
is of considerable size, it is at times necessary to ligature first the large
p
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ii4 THE SURGICAL ANATOMY OF THE HORSE
vessels. Removal of a part of the omentum is also the best procedure
when the part is contaminated by foreign material or when it is necrosed.
Cases which are least hopeful are those in which a portion of the bowel
has been exposed for some time, and there is evidence of superficial
necrosis. With regard to the opening in the abdominal wall, loose
ragged necrosed pieces of tissue should be removed, taking particular care,
however, to save all healthy tissue. It will be gathered, from our descrip-
tion of the blood-supply, that to arrest the haemorrhage it will be
commonly necessary to apply ligatures. The part is then cleansed and
thoroughly disinfected, when the opening in the muscles is closed by
means of stout sutures coarsely inserted. The cutaneous wound is then
closed ; support will be afforded the sutures by applying a few strips of
adhesive strapping. If necessary, the wound can be washed out later by
removing two or three of the sutures in the skin.
Uncomplicated wounds should be dressed and sutured, the deep layer
being sutured separately.
PUNCTURE OF THE ABDOMEN—PARACENTESIS
ABDOMINIS
This is a simple operation performed for the removal of fluid which
has accumulated in the peritoneal cavity. The old practice was to
puncture through the rectum or vagina, but these seats of operation have
been discarded, owing to the obviously greater risk of infection.
In the horse, to avoid injury to the caecum, the seat selected is on the
right side of the wall. A short trocar and canula, with a penetrating
length of from one and a half to two and a quarter inches, depending upon
the size of the animal, should be utilized. The animal remains in the
standing position. The hair is removed from the seat, and the latter is
cleansed thoroughly and washed with antiseptics. A small incision is
now made in the skin with a scalpel. The trocar and canula, which
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RUPTURE OF THE ABDOMINAL WALL
have previously been sterilized, are then taken in the right hand, the
handle of the trocar resting in the palm. The instrument is now
pressed through the wall at right angles, and when the trocar is with-
drawn the fluid escapes through the canula, which is left in position.
Occasionally the discharge of the fluid is arrested by the lumen of the
canula becoming blocked by flocculi of lymph. Its patency should be
restored either by means of a probe or by reinserting the trocar. After
the removal of the liquid, the trocar is replaced and both instruments
withdrawn simultaneously.
RUPTURE OF THE ABDOMINAL WALL-
VENTRAL HERNIA
Occasionally, as a result of external injury, such as a blow with some
blunt object, a kick, or collision, the abdominal wall becomes ruptured,
but the skin remains intact. Through the opening a portion of the
bowel, omentum, or some other internal organ, passes, and is suspended
in a pouch of the skin. The condition is known as a ventral hernia.
The rent in the wall may be due to excessive muscular contraction in the
efforts to expel the foetus during parturition.
The pouch or sac usually consists of skin and panniculus, whilst its
contents are commonly intestine or omentum, though such extraordinary
displacements as portions of the liver, uterus, and bladder, have been
recorded. In the horse the most common seat of the rupture is on the
left side, and the rent extends backwards from the last rib. In some
cases the swelling extends the whole length of the abdominal wall to
the flank. Commonly, however, they vary from the size of a fist to that
of a football.
If seen soon after the injury, the parts are hot and tender to the
touch. Tbey may feel either firm or soft; and if there has been much
haemorrhage the presence of blood may be detected by fluctuation.
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n6 THE SURGICAL ANATOMY OF THE HORSE
Later the inflammatory symptoms subside and the swelling is cold.
Usually it is readily compressible, and in most cases careful manipula-
tion will enable one to detect the hole in the abdominal wall. Most
commonly this latter is elongated, but in some cases it is more or less
circular. It is only in very rare cases that a ventral hernia becomes
strangulated. The methods of differentiating between a hernia and an
inflammatory swelling have already been indicated.
After a while the size of the swelling diminishes perceptibly, and a
small ventral hernia may completely disappear. It is, however, an
added risk in brood mares and in cases of colic and tympanites. For this
reason it is inadvisable to breed from a mare which is the subject of a
ventral hernia.
Animals frequently work for many years with a hernia of this kind
without suffering any apparent inconvenience, and treatment in old-
standing cases is thus rarely adopted. Should it be decided to treat, there
are several different methods which might be employed. A common
method in the case of a small hernia is to apply some irritant which will
corrugate the wall of the sac, and thus cause its contents to be pressed
back into the abdominal cavity. For this purpose sulphuric acid is a
common application. If the neck of the sac be narrow, the application
of a simple ligature is sometimes effective. Most frequently, however,
if the method of ligation be adopted, multiple ligatures must be utilized.
Then quite a large number of different kinds of clams are recommended,
some of wood, others metal. When adopting this method, and also the
method of ligation, care must be taken to ascertain that there are no
adhesions, and that the contents of the sac are completely reducible.
Probably the best clams are those made of aluminium, with a thumb-
screw at each end. They are light yet durable, and the screws enable the
operator to graduate the pressure. Heavy clams have a tendency to slip
off, and also cause too much traction. The length of the clams used
depends upon the size of the sac to be removed. An ample length
should be provided. The contents of the sac are replaced in the
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RUPTURE OF THE ABDOMINAL WALL             117
abdominal cavity; the wall of the sac is then grasped with both hands,
if the sac be a large one, whilst an assistant applies the clams in the
direction of the linea alba usually, quite close to the abdominal wall. At
first the screws should be tightened only to a degree sufficient to
prevent the clam from slipping off. The pressure should be increased
slightly each day by means of the screws. If this precaution be not
taken, the hernial sac may slough away before adhesion above the clam
has taken place. In an ordinary case the sac should slough off in from
seven to fifteen days.
Degive's method is one for which much success has been claimed,
and one which has been frequently employed recently in this country.
The sac is first opened surgically and its contents carefully reduced, any
adhesions being broken down. Large pack-needles are then passed
through the skin and the edges of the rupture in the abdominal wall.
Above the needles a screw clam is applied. The needles are then
removed and horseshoe nails inserted in their stead, the points of which
are recurved. The tissues below the nails become necrosed, and slough
away in about seven days. This method is similarly applied to cases of
umbilical hernia.
In some cases reduction is difficult, and it may even be necessary to
enlarge slightly the opening in the abdominal wall. This should not be
resorted to, however, unless the operator has completely failed in his
efforts to return the protruding organ. Patient manipulation with the
fingers will frequently enable one to reduce successfully in a most un-
favourable-looking case. In this connection it should be remembered
that the greater the difficulty of reduction, the less the probability of
recurrence after the operation has been completed.
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u8 THE SURGICAL ANATOMY OF THE HORSE
NATURAL OPENINGS IN THE ABDOMINAL WALL
We have already referred to the communications between the thoracic
and abdominal cavities through the diaphragm. Here we are concerned
with three openings which pierce the abdominal wall from within
outwards, and which, were they divested of their contents, would place
the abdominal cavity into communication with the exterior. They are
the umbilical opening and the two inguinal canals.
THE UMBILICAL OPENING—UMBILICAL HERNIA
The umbilical opening is placed in the middle line and towards the
front of the posterior half of the linea alba. Through it the umbilical
cord passes in the fcetus. In the ordinary condition the cord practically
fills the ring.
In some cases the umbilical ring in the newly-born animal is
abnormally large, with the result that some of the contents of the
abdomen are pressed out of the cavity through the ring alongside the
cord, constituting an umbilical hernia or omphalocele (exomphalos).
Owing to the fact that the ring closes soon after birth, the hernia is
either present at birth, and is regarded as congenital, or makes its appear-
ance during the first few weeks of extra-uterine life—i.e., is acquired. It
is rare to encounter one which has formed in an old animal.
The wall of the sac is made up of skin and parietal peritoneum, whilst
its contents are usually a portion of the caecum, colon, small intestine, or
omentum. In all cases the umbilical ring is abnormally large. Anything
which tends to pull the skin away from the wall of the abdomen or to
increase the pressure within the abdominal cavity will contribute to the
formation of a hernia here.
There is no tearing of the abdominal wall; consequently inflammatory
symptoms, such as are exhibited in many recent cases of ventral hernia,
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THE UMBILICAL OPENING—UMBILICAL HERNIA 119
are not presented. To confirm diagnosis, the fingers should be pressed
upwards in the middle of the swelling and an endeavour made to locate
the umbilical ring. Usually this can be felt without difficulty.
In many cases in the young animal, an umbilical hernia disappears
spontaneously as the animal takes hard, bulky food. This causes disten-
sion of the bowel, stretches the abdominal wall, and makes the skin and
peritoneum tense, so that the sac becomes obliterated and its contents are
pressed back into the abdominal cavity. The abdominal cavity enlarges
and the mesentery does not proportionately increase in depth so that in a
case of hernia of the small gut the bowel becomes gradually retracted into
the abdomen. It is thus inadvisable to treat at once, but to wait until
the animal is from six to nine months old.
Many and various methods of treatment are adopted. Sometimes
endeavours are made to reduce the hernia by pressure exerted by means
of trusses and plasters of various kinds. Blistering the wall of the hernia
is a popular method, and is very effective in cases where the hernia is
small and its contents readily reducible. Cantharides ointment is
frequently used for this purpose. Occasionally diluted or concentrated
acids are applied, the latter with glass rods in streaks across the sac.
Line firing is also adopted. Practically the same principle underlies the
use of all these irritant applications. Care must be taken not to apply too
severe an irritant (i.e., the lines in firing and in the application of concen-
trated acids must not be too close together) ; otherwise the sac may swell
to such an extent as to rupture, with prolapse of its contents as a serious
sequel.
Another common method of treatment is by ligation. Sometimes an
elastic ligature is applied after reduction of the contents of the sac.
Simple ligation is useful in those cases where the hernia has a narrow
base. To prevent the ligature from slipping off, a needle or skewer is
sometimes passed through the sac below the ligature. When the base is
broad, multiple ligation is resorted to. The animal is placed on its back
and the contents of the sac reduced. The hair is removed from the area,
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i2o THE SURGICAL ANATOMY OF THE HORSE
which is thoroughly disinfected. It is sometimes of assistance to apply a
clam loosely to the wall and in the longitudinal direction. A double-
threaded needle is then passed through the sac and near one end. One
thread is then cut close to the needle, and its ends are passed horizontally
backwards and tied at the hinder end of the sac. The needle with the
other thread is then passed through the sac in the opposite direction, and
about three-quarters of an inch in advance of the point at which the sac
was first penetrated. The ends of this thread, which now hang on the
same side of the sac, are tied. This process is repeated until the anterior
end of the sac is reached, when the whole of the wall will have been
ligatured. It is obviously of importance to note that the contents are
completely reduced, otherwise the needle might penetrate a portion of the
bowel.
Various kinds of clams are also employed, as in the treatment of ventral
hernia, already described, and, failing other methods, herniotomy, in which
the sac is opened surgically, can be performed and the umbilical ring sutured.
THE INGUINAL CANAL
There are two of these, one on either side. Each is a passage through
the posterior part of the abdominal wall. Its length in an average-sized
animal is about four inches, and the direction which it takes is obliquely
downwards, forwards, and inwards. The posterior boundary of the canal
is slightly concave, and is formed by Poupart's ligament. It is smooth
and shiny. Anteriorly the canal is bounded by the fleshy portion
of the internal oblique muscle. The passage is thus placed between the
two oblique muscles, for Poupart's ligament is formed by the reflected
portion of the tendon of the obliquus abdominis externus. The canal
communicates with the cavity of the abdomen superiorly by what
is known as the internal abdominal or internal inguinal ring. On
first examining the area when the abdominal cavity is opened, the term
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THE INGUINAL CANAL
121
ring appears to be appropriate, for one's attention is directed to the small
circular aperture through which the vas deferens passes, and which will
scarcely admit the tip of a finger. This opening is, strictly speaking, the
entrance to the cavity of the tunica vaginalis, and is known as the vaginal
ring. The internal inguinal ring lies beneath the parietal layer of the
peritoneum. After dissecting out the structures which pass through the
canal, however, it will be seen that the aperture by which they enter or
leave the canal is elongated and slit-like. In front of it is the edge of the
internal oblique muscle, which is here quite thin. Behind is the ligament
of Poupart. The length of the opening is about four inches, and its long
axis runs from the prepubic tendon of the abdominal muscles in the direc-
tion of the external angle of the ilium. As stated, the opening as
described is not apparent without a dissection of the part, as a considerable
amount of connective tissue surrounds the structures as they enter or leave
the canal, passes from one structure to another, and also across from the
edge of the internal oblique muscle to Poupart's ligament. The external
inguinal ring is a well-defined slit in the tendon of the external oblique
muscle. Its posterior extremity lies about an inch and a half in front of
the brim of the pubis, and the direction taken by its long axis is
obliquely forwards and outwards. The length of this opening also, in an
animal of average size, is four inches. In the male the spermatic cord
with the cremaster muscle and tunica vaginalis, the external pudic
artery with its satellite vein, and the inguinal nerves (usually two) and
lymphatics, pass through the canal (in the mare the mammary vessels and
nerves pass through it). The external pudic artery and vein, the latter
being smaller than the artery, pass to the back of the cord and slightly to
its inner side. The inguinal nerves, which come from the second and
third lumbar nerves, usually run down one on either side the cord. At
times both are found on the same side. They are distributed to the
prepuce, the scrotum, and the adjacent skin.
The tunica vaginalis is a serous membrane, and is a diverticulum of the
abdominal peritoneum. Like all other serous membranes, it consists of
Q
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122 THE SURGICAL ANATOMY OF THE HORSE
parietal and visceral layers. The parietal layer is directly continuous with
the parietal layer of the peritoneum at the vaginal ring. It has a tubular
portion which lines the inguinal canal, and a distended portion which
lines the scrotum. From the back of the inguinal canal the membrane
becomes reflected around the cord, and it also covers the testicle and the
epididymis, thus forming the visceral layer. The cavity of the tunica
vaginalis communicates with that of the peritoneum through the vaginal
ring.
INGUINAL HERNIA—SCROTAL HERNIA
Opinions differ as to the actual cause of this affection. Many observers
claim that it is practically impossible for a portion of the abdominal
contents to pass into the inguinal canal when the internal opening is of
normal dimension. An examination of the area in the mature animal
appears to support this contention, though Moller reports having
encountered the condition in an animal in which the opening was
unusually small. In many cases a portion of the omentum or small
intestine passes into the canal during the descent of the testicle. Should
it pass down into the scrotum, it constitutes the condition known as scrotal
hernia, so that the latter is simply an extension of an inguinal hernia.
Anything which increases the abdominal pressure, such as tympanites,
predisposes to the condition, as also do violent movements of the parts,
particularly when slipping suddenly backwards and outwards. The latter
tends to dilate the entrance to the canal. Undue traction on the cord
during castration acts in a similar manner. In the stallion, the altered
position of the body during copulation is said to favour the condition.
The size of the swelling varies within very wide limits. At times it is
only diagnosed with the greatest difficulty. In other cases it is reported
to extend downwards as far as the hocks. A portion of the intestine when
in the scrotum is said to lie always to the inner side of the spermatic
cord. Assistance in diagnosis is obtained by exploration through the
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INGUINAL HERNIA—SCROTAL HERNIA             123
rectum. If. the hernia be strangulated, slight colicky symptoms are
exhibited, the respirations are accelerated, the limbs are turned outwards,
and the animal moves stiffly. The twitching upwards of the testicle of
the affected side in the stallion is regarded by many as a diagnostic
symptom. Later the animal is frequently observed to sit on its buttocks,
and vomiting is sometimes seen.
Hernia into the inguinal canal should always be regarded as a serious
condition. Even the most simple cases may become strangulated, when
death is commonly the termination. The most favourable cases are those
in which very young animals are affected. Spontaneous recovery is
common in foals, but is rare in animals of more than one year old.
There are several methods of treating a hernia which is not strangu-
lated, such, for instance, as multiple ligation of the scrotum, as recom-
mended by Bouissy, or applying a ligature around the tunica vaginalis
and spermatic cord. These are methods, however, which are not now
commonly practised. In some cases the application of counter-irritants
over the region of the external inguinal ring is adopted, the object being
the same as in the treatment of umbilical hernia. Another method is to
castrate the animal if it be an entire, and, after reducing the hernia, to fix
the cord in the inguinal canal by suturing its free extremity to the edges
of the external inguinal ring. The most effective method of preventing
a recurrence of the condition would be to suture the internal abdominal
ring, but the difficulties and risks attached to this procedure are obviously
so great that it cannot well become a common practice. By some,
however, attempts are made to occlude this opening by promoting a
swelling of the spermatic cord and bringing about adhesions between it
and the surrounding structures. This is done by rubbing the cord and
scrotum until an inflammatory condition is set up, or by tying a soft
ligature around the scrotum close to the external ring, and allowing it to
remain on for from six to ten hours.
In the gelding the animal should be cast, anaesthetized, and placed on
its back. An incision is made around the scar indicating the seat of
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i24 THE SURGICAL ANATOMY OF THE HORSE
incision when castrated, and the parts dissected until the exterior of the
tunica vaginalis is seen. Clams are then applied after separating the
tunic as high up as possible, the procedure resembling that in castration
by the covered method. Care must be taken to observe that the intestine
or omentum is completely reduced before the clams are applied. If any
doubt exists, it is advisable to incise the tunic and introduce a finger.
A portion of omentum may be removed without any serious results, but
it is better to abstain from this unless reduction is impossible otherwise.
Cases of suspected strangulation call for immediate treatment. The
animal should be cast, placed under an anaesthetic, and turned on its back.
By pulling the leg of the affected side backwards and outwards, the
affected area is better exposed. Attempts are now made to reduce the
hernia by manipulation; meanwhile an assistant passes his hand up the
rectum and applies gentle traction to the portion of the bowel which
enters the inguinal canal. Failing reduction by this method, the operation
of herniotomy is performed under the strictest antiseptic precautions. An
incision is made down to the tunica vaginalis, and this is separated from
the superposed structures by breaking down the fascia with the fingers,
working in this manner along the inguinal canal to within an inch or so
of the internal inguinal ring, where the greatest degree of strangulation
usually occurs. The procedure now is to endeavour to reduce the hernia
by manipulating in the canal with the fingers, and by traction through
the rectum, as before described. Failing this method, and as a last
resource, the tunica vaginalis may be incised, or the internal inguinal
ring even enlarged. For this purpose, special long hernia knives have
been designed by Girard. Having reduced the hernia, the subsequent
treatment is as in those cases where there is no strangulation—namely,
the application of a pair of clams outside the tunica vaginalis and as high
up as possible.
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THE PERITONEUM
125
THE PERITONEUM
This is the serous membrane which lines the wall of the abdominal
cavity. Like other membranes of this kind, it consists of parietal and
visceral layers. In the male it is a completely closed sac, but in the mare
the ostium abdominale of each Fallopian tube opens into it, so that the
cavity communicates through the tube with the uterus and exterior. The
surfaces of these two layers come into close apposition, so that the cavity
between them is only potential. The parietal and visceral layers are
attached to the wall of the abdominal or pelvic cavities and to the outer
surfaces of the viscera by a quantity of subperitoneal tissue. Certain
portions of the peritoneum receive special names. Those portions which
pass from the stomach to other viscera are called omenta. Thus we have
the gastro-hepatic and gastro-splenic omenta, passing from the stomach
to the liver and spleen respectively, and the great or gastro-colic omentum,
which passes from the stomach to the terminal portion of the large colon
and the beginning of the small colon. The mesenteries are those portions
of the peritoneum which suspend the intestines from the roof of the
abdominal cavity, the great mesentery suspending the small intestine, and
the colic mesentery the floating colon. Between the layers of the omenta
and mesenteries the nerves and blood-vessels run. Here also is placed a
quantity of fat and connective tissue, together with lymphatic glands.
Portions of the peritoneum which connect viscera other than the digestive
tube with the wall of the cavity are called ligaments. Thus we have the
ligaments of the liver and bladder, the broad ligaments of the uterus, etc.
Posteriorly the peritoneum extends into the pelvic cavity. This
cavity is bounded superiorly by the sacrum and first three coccygeal
vertebrae, laterally by the ilia and great sacro-sciatic ligaments, and
inferiorly by the pubic and ischial bones. It contains the rectum, portions
of the urino-genital apparatus, muscles, vessels, nerves, etc. The cavities
of the pelvis and abdomen communicate with each other, the line of
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126 THE SURGICAL ANATOMY OF THE HORSE
demarcation being the brim of the pelvis. The peritoneum only lines
the anterior portion of the pelvic cavity. It is a point of great surgical
importance to remember that the membrane does not extend farther back-
wards than the fourth sacral vertebra. Here it is reflected on to the rectum,
and covers the anterior portion of this. Leaving the inferior surface of the
rectum, it forms a small reduplication called the urogenital fold. The free
edge of this passes on either side into the inguinal canal, whilst inferiorly
the fold is reflected on to the bladder. The fold envelops the vasa
deferentia, the anterior portions of the vesiculae seminales, and the uterus
masculinus. The peritoneum passes from either side of the bladder to the
walls of the pelvis, forming the lateral ligaments of the bladder, in which
are the remains of the umbilical arteries of the foetus. Where it is reflected
from the inferior aspect of the bladder on to the floor of the pelvis it forms
a fold which is sometimes called the middle ligament of the bladder.
In the mare the urogenital fold is very much larger, and envelops the
uterus and the anterior portion of the vagina. On either side the
peritoneum forms a large fold which connects the side of the uterus with
the wall of the pelvis and posterior portion of the abdomen. These two
folds are the broad ligaments of the uterus.
The operation of tapping the peritoneal sac (paracentesis abdominis)
has already been described in connection with the removal of abnormal
accumulations of liquid material. The sac is occasionally washed out
with antiseptic solutions in the treatment of certain diseased conditions.
For purposes of description of the internal organs, it has been
customary to divide the abdominal cavity into nine areas by two trans-
verse and two longitudinal imaginary planes. The former passed through
the fifteenth costal cartilages and the external angles of the ilia respectively,
whilst the two latter passed through the middle of the ligaments of Poupart.
The central area is the umbilical. In front of this is the epigastric, on
either side of which is a hypochondriac area. Behind the umbilical area
is the hypogastric, on either side of which is the iliac area. The two
remaining areas were the right and left lumbars.
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THE STOMACH AND INTESTINES                    127
Although now conceded that the value of this division for topo-
graphical purposes has been much overrated, it is given here as being
still of some slight assistance.
THE STOMACH AND INTESTINES
The stomach is placed between the oesophagus and small intestine,
and is the most dilated portion of the alimentary tube. For purposes of
description, it may be said to possess two surfaces, two borders, and two
extremities. Both surfaces are convex, the anterior looking upwards and
forwards and being related to the liver and diaphragm, whilst the
posterior looks downwards and backwards and is related chiefly to the
gastro-hepatic flexure of the large colon. The organ is curved in its
length. Its concave border, which is the lesser, curves upwards and to
the right, the convex border downwards and to the left. The position
of the organ is in the left hypochondriac and epigastric regions, its broad
end, or fundus, extending to the left into the former region; whilst its
right extremity, which narrows down to form the pylorus, is in the
epigastric area. The pyloric end is continued as the duodenum. The
left extremity is related to the base of the spleen and to the pancreas.
Its greater curvature is related to the concave border of the spleen and
to the intestines. The lesser curvature is attached to the back of the
liver by the gastro-hepatic omentum. The oesophagus opens into the
stomach on this border, about one-fourth the distance along it from
the cardiac end. On examining the interior of the organ, it will be seen
that at this orifice the mucous membrane is thrown into folds, and that
the muscular fibres have a peculiar horseshoe-like arrangement, referred
to in Vol. I. wheri dealing with passage of the probang. The mucous
lining will be observed to be divided into two parts by a sinuous
elevation. This is the cuticular ridge. That portion of the membrane
at the left end is pale in colour and harsh. There are no true gastric
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i28 THE SURGICAL ANATOMY OF THE HORSE
glands here, and this part is simply an extension into the stomach of the
lining membrane of the oesophagus, which it resembles. The right
portion is soft and is of a rosy colour. The epithelium is a single layer
of columnar cells, and true gastric glands are numerous. This is the
villous division, and is very highly vascular.
The stomach of the horse is peculiar in that it is so small for such a
large animal, its capacity being only from three to four gallons.
The small intestine commences at the pyloric orifice of the stomach.
It is more or less arbitrarily divided into three portions, termed the
duodenum, jejunum, and ileum, to which are respectively allocated
two, thirty, and forty, of the seventy-two feet which is the length of the
intestine in an average-sized animal. Leaving the stomach, the duodenum
is first related to the back of the liver. Passing over the inferior surface of
the right kidney, it runs to the outer side of the crook of the caecum. It
now passes almost transversely across the spine just behind the root of
the anterior mesenteric artery, and here the jejunum may be said to
commence. The duodenum thus forms a loop, and in this the major
portion of the pancreas is placed. The duodenum is easily distinguished
from the remainder of the small intestine by the fact that it is relatively
fixed in the position described. The jejunum and ileum form a great
number of coils in the umbilical, iliac, and hypogastric regions. They
are freely movable, inasmuch as they are attached to the free edge of a
very broad fold of peritoneum known as the great mesentery. The
posterior extremity of the ileum projects for a short distance into the
crook of the caecum, and here regurgitation from the caecum into the
ileum is prevented by an arrangement known as the ileo-caecal valve.
The surface of the small intestine differs from that of the large in that,
when distended, it is not puckered, but is smooth.
The large intestine is much more naturally subdivided, the parts
being known as the caecum, colon, and rectum, respectivelv. The
caecum has an average length of about three feet, and a capacity of about
four gallons. It tapers anteriorly to a blind blunt extremity. Posteriorly
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THE STOMACH AND INTESTINES
129
it is curved, forming what is known as the crook. This is connected
with the right kidney and the pancreas, and is attached in the right
sublumbar region by means of loose connective tissue, from whence
the caecum runs downwards and forwards through the right hypo-
chondriac region to the epigastric area, where its blunt termination is
usually placed. Only the crook, however, is fixed, so that the remainder
is subject to considerable displacement.
The colon is sharply divided into two portions. The first of
these, which immediately succeeds the caecum, is the double or large
colon. The orifice by which its lumen communicates with that of the
caecum is placed above the ileo-caecal valve, and is on the concave border
of the crook. The large colon is from nine to twelve feet in length, and its
■ average capacity is about sixteen gallons. Leaving the caecum, it runs
downwards and forwards to the epigastrium, through the right hypo-
chondriac region. Here it curves to the left, forming what is termed the
suprasternal flexure. Its course is now directed backwards, on the left side
of the abdomen, to the entrance to the pelvis, where it curves upwards,
forming the pelvic flexure. There have thus been formed two fairly
distinct parts, and they are referred to as the first and second portions
respectively. There are two other portions, known as the third and
fourth. The third runs forwards above the second part. In the
epigastric region it curves to the right, forming the diaphragmatic or
gastro-hepatic flexure, and here the colon is in intimate relationship to
the posterior aspect of the stomach, liver, and diaphragm. The fourth
part runs backwards above the first, to which it is closely related.
Posteriorly it is attached to the inner side of the crook of the caecum,
and here it suddenly narrows down, and is continued as the floating or
small colon. This is where intestinal obstructions are usually arrested.
So long as they remain in the large colon and stationary, they may attain
enormous proportions without subjecting the animal to apparent incon-
venience, for the wall of the bowel forms a pouch for their accommoda-
tion. Calculi of great weight have been discovered thus when making
R
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130 THE SURGICAL ANATOMY OF THE HORSE
post-mortem examinations on animals which have lived many years longer
than an average life. Serious difficulty arises when an attempt is made to
pass the obstacle into the floating colon, for, owing to the sudden
narrowing down of the lumen, the latter becomes blocked and the
obstacle arrested. It is for this reason that the incision is made in the
right flank when operating (see Laparo-enterotomy). The fourth portion
has the broadest lumen, and the third the smallest. Moreover, the
fourth portion is not puckered when distended. The small or floating
colon has a length of about ten feet. Its lumen is little greater than
that of the small intestine, but its surface is puckered. Although it
commences on the right side, it is mainly placed in the left lumbar and iliac
regions, where it is coiled up very much after the manner of the small
intestine at the free edge of a portion of the peritoneum known as the
small mesentery. It is continued as the rectum, which in an average-
sized animal has a length of about two feet. The rectum passes straight
backwards to the anus. At its anterior end it is puckered, and is not
unlike the small colon. Posteriorly it is much dilated and sac-like.
Here the fasces collect.
The wall of the stomach and intestines is formed by serous, muscular,
submucous, and mucous layers.
FISTULA OF THE BOWEL
In the physiological laboratory, this is a condition which is frequently
induced for the purposes of scientific investigation. The term is applied to
a direct communication between the lumen of the bowel and the exterior
through the bowel and abdominal walls. The condition may arise as the
result of an injury. It is obvious that, in cases of penetrating wounds of
the abdomen when the intestine is pierced, an adhesion between the edges
of the wounds in the intestine and abdominal walls will lead to the
formation of a fistula, or a fistula may arise as a result of an internal
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FISTULA OF THE BOWEL                           131
affection. Inflammation of the wall of the intestine, leading to an
adhesion between its exterior and the inner surface of the abdominal
wall, is sometimes complicated by abscess formation, and in this manner
the abdominal wall may be perforated and a fistula formed. Fistula not
infrequently arises as a result of the careless treatment of a hernia. The
condition is, of course, chronic, and the animal exhibits little systemic
disturbance apart from a loss of flesh. The persistency of the case
is due to the continuous discharge of the bowel contents. This
should therefore be arrested, and the treatment should follow general
lines. The edges of the opening should be scraped, and an endeavour
made to bring them into apposition. If the aperture be small, the
application of biniodide of mercury ointment will frequently promote
sufficient swelling to effect a closure. Failing this, deeply-laid sutures
should be inserted, one or two simple interrupted sutures passing across the
opening, and a stout purse-string suture around it. Care must be taken,
when curetting the wall, to break down any adhesion between the bowel
and abdominal wall, and also to include in the sutures the wall of the
abdomen and the skin. Failure to take the latter precaution frequently
leads to subsequent abscess formation, with a recurrence of the fistula.
PUNCTIS INTESTINI—ENTEROCENTESIS
This is the term applied to the operation of puncturing the bowel.
The operation becomes necessary in those cases of colic in which the
caecum and large colon are distended owing to an abnormal production of
gas within. The pressure of the distended viscera on the diaphragm
interferes with respiration to such a degree that in many cases, unless
surgical relief be afforded, the animal will die from suffocation. The
operation is one which demands special care, both in the selection of the
seat of puncture and during the manipulation of the instrument. Coils of
the small intestine are insinuated between the wall of the abdomen and a
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132 THE SURGICAL ANATOMY OF THE HORSE
great portion of the large colon. The gas usually collects in the parts of
the bowel which are placed superiorly, the inferior portions being
occupied by masses of food material. The broad end or base of the
caecum is fixed on the right side, and this portion it is desirable to
puncture. The operative area is triangular in outline, and may be mapped
out as follows : From the external angle of the ilium draw a horizontal
line along the tips of the transverse processes of the lumbar vertebras
forwards to the last rib. From the anterior extremity of this another
line should be drawn downwards to the middle of the rib. An oblique
line joining the inferior extremity of this line to the posterior end of the
line first drawn will indicate the third side of the triangle. The area
included between these lines must be carefully examined and percussed,
the point actually selected being that which presents the greatest degree
of distension and a resonant sound. Friedberger's trocar is probably the
best instrument on the market. The trocar is trifacial at its extremity, and
the canula has a very fine bore and is without side-holes. The instrument
should be rendered strictly aseptic by boiling, and the operative area
shaved and cleansed thoroughly. If time will permit, spirit or ether should
be employed for cleansing. A small incision should be made in the skin with
a scalpel. The skin should now be drawn a little forwards or backwards
with the left hand, and the trocar pressed inwards in a perpendicular
manner with the right for a distance of three to four inches, depending
upon the size of the animal. It should be remembered that both the
oblique muscles of the abdomen, together with the transversalis, have to be
pierced. Gas escapes through the canula when the stilette is withdrawn,
and the former is left in position until gas ceases to accumulate. This
can be tested by closing the canula for a time with a small cork. If after
withdrawing the latter no gas escapes, the canula may be removed. This
is done by reintroducing the stilette and withdrawing botn together.
The skin will slip back into position and cover the puncture in the
abdominal wall.
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LAPAROTOMY
!33
LAPAROTOMY
This is the term applied to the operation of opening into the
abdominal cavity. A view which was generally held was that the
peritoneum of the horse was peculiarly susceptible to peritonitis, rendering
any operation which necessitated opening the wall of the abdomen much
more dangerous than in other species. This view is still held by many.
Macqueen, in a valuable paper read before the National Veterinary
Association in 1895, cited a large number of varied cases of injuries
perforating the wall of the abdomen which were successfully treated, and
did much to show that the theory as to the greater degree of susceptibility
of the horse to inflammation of the lining membrane of the abdominal
cavity was somewhat exaggerated. This contention is strongly supported
by the now common practice of operating on cryptorchid horses with very
slight antiseptic precautions. Macqueen showed that incisions could with
ordinary precautions be made in the abdominal wall, and that the
abdominal contents could be handled with no extraordinary risk to the
patient. In 1849 Felizet, without the aid of anaesthetics or antiseptics,
successfully performed the operation of laparo-enterotomy (i.e., incising
the abdominal and bowel walls) on a horse affected with calculus arrested
near the entrance to the floating colon.
Macqueen, in the paper referred to, reported two successful cases in
which the operation was performed experimentally. Unfortunately, no
obstruction was present, so that the case of Felizet remains the only one
in which the operation has been performed and an obstruction removed.
Macqueen, however, demonstrated that the operation was possible, and
that the record of Felizet's case was by no means incredible. The non-
success of the attempts of other operators is probably explained, as Dollar
states, by their having delayed the performance of the operation until it
was too late to afford the case a fair chance of recovery.
Macqueen's method was as follows :
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i34 THE SURGICAL ANATOMY OF THE HORSE
The seat selected was the right flank. Here is placed the beginning
of the floating colon, where the fourth part of the large colon becomes
suddenly narrowed down, and this is where the obstruction is usually
arrested. With the first incision he divided the skin, fascia, and external
oblique muscle, the incision commencing " at a point four inches below
the lumbar transverse processes, and midway between the angle of the
haunch and the last rib," and extending in an oblique manner downwards
and forwards for seven or eight inches. " The upper hind limb is
unhobbled and drawn backwards. The wound gapes and exposes the
internal oblique muscle, which is then cut with scissors in the direction of
its fibres. A similar opening is made in the transversalis. The third
wound exposes a layer of fat which is lined by peritoneum; this is
pierced with the finger, and the opening is enlarged with scissors in the
direction of the transversalis wound." He then " opened the bowel at
the middle of the longitudinal band, where the wall appears strongest and
most capable of supporting sutures." With sharp-pointed elbowed scissors
the gut can be punctured and the wound extended without the slightest
difficulty. The contents of the bowel having been removed, the edges of
the wound were cleansed with a fresh sponge, and the wound was then
closed by inserting Lembert's sutures. The stitches were placed one-
eighth of an inch apart, and two or three were inserted beyond each
extremity of the wound. The sutures were not tied until all had been
passed. Having sponged the part, it was then " douched with boiled water
which had been cooled to 1060 F., the packing around the wound was
removed, and the assistant by whom the loop of bowel was held allowed
it to slip back into the abdominal cavity. The wound in the transversalis
muscle was not sutured, but its edges were adjusted. The opening in the
internal oblique muscle was closed by inserting two or three sutures. The
upper hind limb was now placed back in the hobble, and the edges
of the external oblique muscle were brought together by inserting a few
fine sutures. The external wound was closed by passing a number of
sutures through the skin and muscle. A slit was now made obliquely down-
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INJURIES TO THE RECTUM AND ANUS             135
wards and backwards for a length of two inches from the lower extremity
of the first incision, for the purpose of draining the operation wound. The
area was then washed and cleansed, and the animal allowed to rise.
Aseptic tow was inserted in the drainage wound, the area dusted over with
dry dressing, and then covered by carbolized cotton and gauze. These
were kept in position by winding bandages around the body. The horse
was muzzled, but was not tied up. The part was not disturbed until there
was oozing from the surface, when the dressings were renewed. It is
scarcely necessary to state that the whole procedure was carried out under
the strictest antiseptic precautions.
INJURIES TO THE RECTUM AND ANUS
These are common, and are due to a variety of causes, such as the
careless introduction of a clyster syringe or by the penis during coition.
Occasionally the injury is inflicted maliciously. The wall of the rectum
may be damaged by the foetus in the mare during parturition, or it may
be accidentally incised during the performance of the operation of ovari-
otomy. In connection with such injuries, it should be remembered that
the posterior portion of the rectum for a length of from nine to twelve
inches — depending upon the size of the animal—has no peritoneal
covering, so that laceration or puncture of this portion does not open
into the peritoneal cavity. Injuries to the anterior portion are, therefore,
much the most serious, and, according to some authorities, such wounds,
when the wall of the rectum is perforated, always terminate fatally.
That portion which is not covered by peritoneum is surrounded by a
quantity of loose connective tissue, by which it is attached superiorly to
the inferior surface of the sacrum, and inferiorly in the male to the wall
of the bladder, and in the female to the uterus and part of the vagina.
Penetrating wounds of this part not infrequently lead to inflammation and
thickening of this tissue. Occasionally secondary strangles abscesses
develop in it.
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136 THE SURGICAL ANATOMY OF THE HORSE
In cases where such conditions are suspected, it is advisable to give
a guarded prognosis prior to exploration of the part, in order that no
blame may be attached to the one conducting the examination, for the
original injury.
The method of procedure depends upon the nature and seat of the
injury or affection. It is usual to evacuate the rectum and wash it out
with antiseptic solutions. Such injections are, however, contra-indicated
when the wounds communicate with the peritoneal cavity, since they only
tend to carry infective contents of the bowel into that cavity. In these
cases little can be done beyond the administration of sedatives to restrict the
movements of the bowel. Wounds near the anus may be sutured. Cold
injections are frequently useful in checking haemorrhage. With regard to
the treatment of abscesses, much depends upon their position. According
to general principles, their contents should be evacuated as soon as possible,
and the point to be considered is that this should be done in the least
dangerous manner. In the mare the abscess can frequently be opened
through the vagina; but in those cases where the abscess is not far distant
from the anus, its contents can be evacuated by making an incision in the
skin near the anal opening, but clear of the sphincter muscles, and by
insinuating the finger or a blunt probe alongside the wall of the rectum.
The consecutive treatment is as usual.
Woodruff recently had a case in which there was a large rent in the
wall of the rectum, through which fasces escaped. He opened the left
flank, withdrew a loop of the floating colon, and performed colotomy,
providing an artificial anus. The patient did well, and under local treat-
ment by irrigations the rent in the rectum closed. As Woodruff stated,
had the animal (a mare) been required for breeding purposes " or for use
on a farm, she might have been left alone " ; but as she was required " for
town work, an attempt was made to join up the two separated ends of the
small colon." This was done, but during its performance " an unfortunate
accident happened, in that the upper piece of bowel was cut into and
fascal matter escaped into the wound, soiling the edges of the incision."
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PROLAPSE OF THE RECTUM AND ANUS           137
Apart from this there seems little doubt but that the case would have
recovered. The mare died two days later, and the post-mortem revealed
*' a slight defect in suturing at the omental attachment of the gut; other-
wise the join was beautifully healed." As Woodruff stated, " this case,
although eventually unsuccessful for the reasons given, certainly confirms
the opinion held by Professor Macqueen, that bowel surgery may be
performed in the horse without fear of any supersensitiveness of the
peritoneum."
PROLAPSE OF THE RECTUM AND ANUS
After each act of defalcation in the horse, the mucous membrane of
the posterior end of the alimentary tube is for a short time exposed.
When this protrusion is permanent, it constitutes the condition known as
prolapse. The length of the prolapsed portion varies; it may be simply
the anus or posterior portion of the rectum. In these cases the connective
tissue surrounding the tube must be first torn. Occasionally, however,
more anterior portions of the bowel which are clothed by peritoneum are
exposed, and are invaginated in the posterior end of the rectum, which
remains fixed.
The condition most frequently results from a severe attack of diarrhoea.
Increased peristaltic action and abdominal pressure force the bowel out
of position. Violent struggling whilst hobbled, irritation of the mucous
membrane by clysters which are too hot, and difficult parturitions, have
also been followed by prolapse.
To distinguish between ordinary prolapse and prolapse with invagina-
tion, an attempt should be made to insinuate the hand flatwise between
the prolapsed portion and the wall of the rectum. This can be done in
cases of invagination.
In recent cases the mucous membrane is cleansed and the prolapsed
portion replaced by steady pressure with the hand. Should there be
s
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138 THE SURGICAL ANATOMY OF THE HORSE
invagination, it is obvious that the hand must be passed up the intestinal
passage to a much greater length than that of the exposed portion of
bowel, in order that the invagination may be obliterated. If the mucous
membrane be much swollen, superficial scarification is sometimes adopted,
or the part is washed with some astringent lotion. These facilitate its
reposition. The diarrhoea should be treated by internal medication.
Usually the difficulty in replacement is not great, but the tendency is for
a recurrence of the condition. There are several methods of preventing
this, such as the internal administration of sedatives, the smearing of the
interior of the rectum with cocaine ointment, or the occasional injection
of some sedative lotion. The hind feet should stand on high ground,
and observation be kept on the animal for several hours. Should signs of
straining appear, one or other of the various methods of exerting pressure
on the loins should be adopted.
Some operators, to prevent a recurrence, insert one or two tape sutures
transversely across the anus, the ends of the sutures passing under the skin
on either side. Others, again, adopt Andre's suture, which passes
circularly in the skin around the anus, and which is inserted after the
manner of a pouch-string.
If the prolapse has existed for some days, and its surface shows signs
of structural alteration, it is not advisable to attempt replacement, and
removal of the protruding portion becomes necessary. Some operators
adopt methods which cause the projecting portion to slough away, such,
for instance, as the application of caustics or the use of simple or
multiple ligatures. If ligation be adopted, it is obviously necessary to
keep the anus patent. For this purpose Stockfleth devised a wooden
tube, the exterior of which presented a groove into which the wall of
the bowel was pressed by the ligature. This kept the tube in position
and hastened the process of sloughing.
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TUMOURS AND CYSTS IN THE RECTUM AND ANUS 139
FISTULA OF THE RECTUM OR ANUS
These are not uncommon. Some are congenital, such as many of
those which place the rectum and vagina in communication. Others are
the results of injuries during parturition, or of wounds which have not
been effectively treated. A careful search should be made for the opening
of the canal, and the direction which it takes accurately ascertained by
means of a probe. Treatment should then follow the general principles
which have already been described—namely, to lay open the canal and
dress with antiseptics which are also slightly caustic. Simple injections
without surgical interference are rarely successful. The sphincters of the
anus should, however, not be incised if they can possibly be avoided.
TUMOURS AND CYSTS IN THE RECTUM AND ANUS
These are not uncommon in horses. Here the melanotic carcino-
mata which are so peculiarly associated with grey horses are most
frequently seen, and they are usually placed near the root of the tail.
Other different kinds of tumours, which may have diffused bases or be
more or less pedunculated, are not unusually associated with the rectum.
It is not difficult to detect them when they are placed close to the anus,
as they may be readily seen. Others situated farther in the passage present
much greater difficulty. At times their presence is accidentally detected
when examining the rectum for some other purposes. In some cases
difficulty in defalcation leads the observer to suspect their presence,
whilst in others, which are placed near the hinder end of the rectum, the
tumours become visible at the anal orifice during each act of defalcation.
Treatment depends largely upon the nature, position, and size of the
growth. If these permit, extirpation should be practised. The removal
of some growths placed immediately subcutaneous and near the anus is a
very simple matter. Pedunculated tumours and cysts in the rectum, when
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i4o THE SURGICAL ANATOMY OF THE HORSE
not too forwardly placed, also present little difficulty. In other cases a
thin chain or wire ecraseur is probably the best instrument to be used.
In pedunculated cases ligation is commonly practised.
Hemorrhage can be controlled either by plugging the rectum or
washing it out with cold astringent solutions.
RECTAL EXPLORATION
In the diagnosis of many internal affections in the horse, exploration
through the rectum is such a valuable aid that the importance of its
frequent practice cannot be too strongly emphasized. It is only by
constant and repeated attempts that a sense of the normal " feel" of the
various structures encountered can be acquired. Macqueen gave the
results of his observations on this point in a paper read before the
National Veterinary Association in 1895, and these are so useful that
indulgence is sought for inserting them here at length. He says that
"the height of the operator and the length of his arm should be
considered as well as the state of the horse's bowels. In a healthy horse
fifteen hands high and of medium coupling, the hand may reach the
cceliac axis and the last rib. In a long-loined sixteen-hands carriage
horse, lying on his right side, I have felt without difficulty the border of
the spleen, the last rib, and the left kidney ; but in the standing horse I
have never reached the spleen. Experiment warrants the assertion that
an imaginary vertical plane falling from the last lumbar vertebra to
midway between the xiphoid and umbilicus represents the forward limit
of rectal exploration. Employing the left hand for the right half and the
right hand for the left half of the abdomen, all the viscera behind this
boundary may be examined more or less satisfactorily in the healthy
horse. In abdominal disease, especially in obstruction, the intestines are
often crowded towards the pelvis, and frequently the hand cannot pass
onwards in consequence of straining and pressure from distended bowels.
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THE LIVER
141
But when the hand has reached the flank, it may, and sometimes does,
discover displacements, volvulus, or invagination; recognize and remove
concretions ; ascertain the condition of the contents of the colon, caecum,
floating colon, and small intestine ; and in hernias distinguish and liberate
omentum and bowel. Cases that give no sign to exploration are
uncommon, and without this precious aid diagnosis, whether positive or
negative, is doubtful. In this, as in other diagnostic efforts, the spirit of
the practitioner dominates procedure. With faith in possibilities, rectal
exploration may be tried again and again, and information may be gained
at every exploration."
THE LIVER
This is [the largest glandular organ in the body. It is of a very
irregular shape, is reddish-brown in colour, and is placed immediately
behind the diaphragm. Its average weight is about twelve pounds.
Inferiorly it is split by a number of notches. Two of the largest of these
divide it into three main lobes—namely, right, left, and middle. The
middle, or lobulus quadratus, is the smallest. In old subjects the left
lobe is larger than the right, but in the immature animal the left is the
smaller. At the upper end of the right lobe is a small projection, which
is the homologue of the human lobulus caudatus.
The anterior surface is convex and related to the diaphragm. It
presents a vertical groove down which the posterior vena cava descends
to the foramen dextrum. The posterior surface is slightly concave. On
this surface is the portal fissure, by which the portal vein, hepatic artery,
nerves, and lymphatics, and the bile duct, enter or leave the liver. Its
superior border shows a deep notch through which the oesophagus passes
to the stomach. The inferior border presents the two notches which
divide the organ into its three main lobes, and a number of smaller
notches. The posterior surface is related, near the upper border of the
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142 THE SURGICAL ANATOMY OF THE HORSE
right lobe to the right kidney, to the duodenum, stomach, the large
colon, and the pancreas.
Blood is carried to the liver from the spleen and digestive tract by
the portal vein. The hepatic artery is, however, the nutrient vessel.
Blood leaves the organ by the hepatic veins, which empty themselves
into the posterior vena cava, where the latter lies in the groove on the
front of the gland.
Its nerves come from the hepatic flexus, to the formation of which
the vagus and sympathetic nerves contribute.
Regarding its position in the body, the greater part of the liver lies
to the right of the middle line. Its right lobe extends to the highest
level—namely, that of the right kidney. The left lobe extends to the
lowest level, its extremity being placed from three to four inches from
the floor of the abdomen, and opposite the seventh intercostal space.
The liver is held in position by a number of folds of peritoneum,
referred to as the ligaments of the liver. Thus, we have the right lateral
ligament, passing between the right lobe and the rim of the diaphragm;
the left lateral ligament, running from the tendinous centre of the latter
to the left lobe; and the falciform or suspensory ligament, which runs
from the middle lobe to the diaphragm and floor of the abdomen, and the
posterior border of which contains what is sometimes called the round
ligament, but which really represents the remains of the umbilical vein.
A small fold passes from the front of the right kidney to the right lobe.
This is the ligament of the caudate lobe. Lastly we have the coronary
ligament, which attaches the organ to the posterior face of the diaphragm
on either side the anterior fissure.
The liver is the gland by which the bile is formed. The hepatic
duct, which conveys the bile to the intestine, is formed at the portal
fissure by the union of right and left ducts. It has a length of only
about three inches, whilst its diameter is half an inch. To reach the
duodenum, the wall of which it pierces obliquely, it runs between the
two layers of the lesser omentum.
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THE PANCREAS
r43
THE PANCREAS
This is the gland which secretes the pancreatic juice. It is sometimes
called the false sweetbread. It is placed near the roof of the abdominal
cavity, its central portion lying beneath the last two or three dorsal
vertebra. Its superior surface, which looks upwards and slightly
forwards, is related to the pillars of the diaphragm, the posterior vena
cava, posterior aorta, the right kidney and adrenal body, and the coeliac
axis. This surface is partly covered by peritoneum. The inferior surface
is concave. Towards the right it is related to the crook of the caecum,
and another larger depression accommodates part of the large colon.
Only a small portion at the anterior angle of this surface is covered by peri-
toneum. The pancreas has two borders: an anterior, which is related to
the stomach, duodenum and liver; and a posterior, to the centre of which
the root of the anterior mesenteric artery is related. The thicker end
of the gland, or head, is towards the right, and is related to the duodenum.
Its left end, or tail, is related to the base of the spleen. The gland is
pierced by what is known as the pancreatic ring, through which the
posterior vena cava passes. Two excretory ducts leave the right end of
the pancreas; the larger is the duct of Wirsung, and it pierces the wall
of the duodenum near the hepatic or bile duct. The smaller penetrates
the wall on the opposite side. In the fresh subject the pancreas is
yellowish in colour, but post-mortem changes quickly render it almost
black. It is supplied with blood by branches of the coeliac axis and
anterior mesenteric artery, and its nerve-supply is derived from the coeliac
and mesenteric sympathetic plexuses.
THE SPLEEN
This is the largest of the ductless glands, and it lies against the left or
cardiac end of the stomach. In the horse it is sickle-shaped, and presents
an outer face which is slightly convex and is related to the diaphragm.
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i44 THE SURGICAL ANATOMY OF THE HORSE
Its inner face is related to the double colon, and is slightly concave. Its
anterior border embraces the greater curvature of the stomach. This
border is thick, and is penetrated by the vessels of the organ. Its posterior
border is convex, free, and lies between the diaphragm and the intestines.
Its base is related to the left kidney and to the pancreas.
It lies chiefly in the left hypochondriac region, has an average weight
of a little over two pounds, and a length of eighteen to twenty inches. It
is held in position by the gastro-splenic omentum, which connects the
anterior border of the organ with the greater curvature of the stomach,
and by the splenic or lieno-renal ligament—a fold of peritoneum which
passes from the front of the left kidney to envelop the spleen.
The splenic artery supplies the organ with blood, and its nerves come
from the splenic plexus.*
THE LOINS
A transverse vertical section through the posterior portion of the
lumbar region is represented in Plate XIV. Above the transverse pro-
cess is a mass of muscle, made up chiefly of the middle gluteus and
longissimus dorsi. These have already been described. Below the
process there is another mass, forming what are known as the sublumbar
muscles, which include the following :
'Psoas Parvus.—This muscle arises from the bodies of the last three
dorsal and the first five lumbar vertebras. It is an elongated and flattened
muscle, and its outer portion is tendinous. The width of its tendon
increases until it reaches the pelvic inlet, where it narrows down and the
tendon passes to its insertion into the ilio-pectineal eminence. Its superior
surface is related to the vertebras, to the lumbar nerves, and in part it
conceals the psoas magnus. Inferiorly its anterior portion, which is
* The liver, pancreas, and spleen, are described briefly to add to the completeness of the work.
In the present state of our knowledge of abdominal surgery in the horse, they have little surgical
importance. In the physiological laboratory, operations are frequently performed on them in the dog.
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THE LOINS
H5
within the thorax, is related to the sympathetic nerve, the crura of the
diaphragm, and to the pleura; whilst the abdominal portion of the right
muscle is related to the posterior vena cava, the sympathetic nerve trunk,
the right ureter, and the peritoneum. This portion of the left muscle, in
addition to the sympathetic nerve cord, left ureter, and peritoneum, is
related to the left kidney and the posterior aorta.
Both muscles, acting simultaneously, flex the pelvis on the loins. If
only one acts, the pelvis is inclined laterally. They derive their blood-
supply from the intercostal and lumbar arteries, and their nerve-supply
comes from the lumbar nerves.
'Psoas Magnus.—This is much larger than the preceding muscle, by
which, as stated, it is partially covered. It is broadest in front, and its out-
line is somewhat triangular. It arises from the inferior surfaces of the
transverse processes of the lumbar vertebras and the upper portions of the
last two ribs. Its middle is thick and fleshy, its edges being much
thinner. Posteriorly it becomes rounded and more or less conical, and is
continued by a powerful tendon which passes downwards and backwards
to become inserted into the internal or small trochanter of the femur in
common with that of the iliacus muscle. Superiorly it is related to the
two last dorsal vertebrae and corresponding ribs and internal intercostal
muscles, to the lumbar vessels and nerves, and to thequadratus lumborum,
longissimus dorsi, and iliacus muscles. Inferiorly it is related to the iliac
fascia, peritoneum and pleura, the diaphragm and sartorius muscle, the
kidney and intestines. This surface is crossed by the circumflex iliac
artery, and part of it lies on the psoas parvus.
The psoas magnus is a flexor of the hip joint and an outward rotator
of the thigh. The lumbar and circumflex-iliac arteries provide its
blood-supply, and its nerve-supply is derived from the lumbar nerves.
Quadratus Lumborum.—This muscle arises from the inferior surfaces of
the lumbar transverse processes and the upper portions of the last two ribs.
It is inserted into the sacro-iliac ligament and the anterior border of the
sacrum. It is a thin muscle with tendinous fibres running throughout.
T
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146 THE SURGICAL ANATOMY OF THE HORSE
Superiorly it is related to the last two ribs, the lumbar transverse processes,
and branches of the lumbar arteries. Inferiorly it is related to the psoas
magnus, and between these two muscles the last intercostal and the first
three lumbar nerves run. One muscle acting singly assists in curving the
loins to that side. Both muscles acting together assist in fixing the ribs
and lumbar vertebras. The lumbar nerves and arteries supply it.
All the above muscles are paired.
The psoas magnus and iliac us are intimately related, and are sometimes
described together as the ilio-psoas muscle.
In this region there are also strands of muscle fibres connecting
the adjacent transverse processes. These are the intertransverse muscles of
the loins.
STRAIN OF THE PSOtE MUSCLES
Regarding this condition there is considerable divergence of opinion.
Some clinicians deny its existence, whilst others include under this term
several other affections which are now readily distinguishable.
According to W. Williams, it arises as a result of the animal's being
cast in the stall, or by any other accident which causes undue extension of
the psoas muscles.
From our description of the muscles, it will be deduced that inability
of them will have a marked effect upon the control of the hind limbs.
Paralysis resulting from a broken back can be readily distinguished, since
in the case under consideration the animal, when lying down, retains the
power of flexing and extending the lower joints of the limbs. Frequently
the animal goes down and is unable to rise. If assisted up and placed in
slings, he is able to stand if the feet be placed in position and flat on the
ground. Williams states that " there is always a marked tendency to
knuckling over at the fetlock joints." Should the strain be not severe,
and the animal be able to stand, if compelled to move forwards he will be
observed to drag the hind limbs. Rectal exploration will assist in diagnosis,
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THE LUMBAR VERTEBRA—FRACTURE
for it will reveal heat and tenderness over the affected area on palpation.
Williams further describes a " swelling around the rectum and perineum,
or vagina, if the patient be a mare," which appears within a few hours of
the accident.
The old practitioners frequently confused hemoglobinuria with this
affection. In our present knowledge of the former disease, such confusion
is now highly improbable.
Treatment consists in placing the animal in slings, and applying mild
counter-irritants to the loins after hot fomentations, for two or three days.
Some inject warm enemata, claiming that they act as internal local
fomentations. If there is systemic disturbance with elevation of
temperature, febrifuges should be administered internally. The usual
atrophy of inaction occurs, and to endeavour to restore the bulk of
muscle the loins are sometimes blistered and the animal turned out to
grass.
THE LUMBAR VERTEBRA—FRACTURE
There are usually six members of this series. Their centra are inter-
mediate in length between those of the cervical and dorsal regions, and
their extremities are flatter. The arches of the first two members are
similar to that of the last dorsal vertebra, but in the remaining four the
breadth and height of the arch progressively diminish as we proceed back-
wards. The articular processes are small, and mammillary processes are
fused to the anterior pairs. The most characteristic feature of these
vertebra? is the enormous size of the transverse processes. These are large
plates which project outwards and curve slightly downwards. The first
two bend slightly backwards, the last two forwards. They are all
flattened from above to below. Synovial joints are formed between the
fifth and sixth transverse processes and between the latter and the anterior
border of the sacrum. The superior spines are well developed, and
resemble that of the last dorsal vertebra.
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148 THE SURGICAL ANATOMY OF THE HORSE
As in the case of the dorsal vertebra?, these bones are particularly well
clothed by muscles. The major portion of what has been written regard-
ing causation, and course of fracture of the dorsal vertebra? will also
apply to fracture of these bones. The only portion of a lumbar vertebra
which is more liable to injury is the outer end of the transverse process,
and this more particularly in animals in which the muscles are poorly
developed.
The first lumbar and last dorsal vertebra? are generally regarded as the
weakest bones in the spinal column, and, moreover, they are placed where
the greatest pressure is placed upon the bones during curvature. It is not
surprising, therefore, that these are the two bones which are most
frequently fractured. According to Moller, Paltz and Degive observed a
greater predisposition to osteomalacia, with, of course, a liability to fracture,
in portions of the bones in the lumbar region.
THE CROUP AND TAIL—THE SACRUM AND
COCCYGEAL VERTEBRA—FRACTURES
The five vertebra? in the region of the croup are fused together,
forming what is known as the sacrum. The single piece thus formed
may be said to possess two surfaces, two borders, a base, and an apex, so
that in outline it is somewhat triangular. In the middle line on the
superior surface are the five superior spines, the bases of which are com-
pletely fused. The summit of the first spine is sharp ; that of each of the
others is rough and tuberous. The first two spines are almost equal in
height. The height of the others diminishes progressively backwards.
Thus we have the gradual decline of the body down the croup to the root
of the tail. On either side the row of spines there are four superior sacral
foramina, through which the superior primary divisions of the spinal
nerves in this region pass. Towards the front of this surface on either
side is a roughened area which looks upwards and outwards. It is the
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THE CROUP AND TAIL                              149
auricular facet, which articulates with the innominate bone. The sacro-
iliac ligament is attached near this facet. The inferior surface forms the
roof of the pelvic cavity. It is concave from before to behind, and is
smooth. Four faint markings cross it transversely, and these indicate the
lines of fusion of the originally separate segments. There are eight inferior
sacral foramina opening on this surface, four on either side the middle
line. They transmit the inferior primary divisions of the spinal nerves.
The lateral edges are sharp and irregular, and give attachment to the great
sacro-sciatic and inferior ilio-sacral ligaments. The base or anterior border
shows the neural ring, beneath which is the anterior end of the first sacral
centrum. It is slightly convex, and is transversely elongated. On either
side of this is another elliptical facet. These form synovial joints with
like facets on the posterior borders of the two last lumbar transverse
processes. At the apex of the triangle the neural ring is observed to be
triangular in outline. Above it is the posterior border of the last neural
spine, and below it the hinder surface of the centrum of the last sacral
segment. This is nearly flat, and is united by intervertebral substance to
the first coccygeal vertebra. A pair of rudimentary transverse processes
project backwards at this end, but the oblique processes are not represented.
Anteriorly there are two small oblique processes.
The coccygeal vertebras are usually eighteen in number. They are the
bones of the tail, and are placed behind the sacrum. The first coccygeal
vertebra is sometimes ossified to the last sacral segment, which it closely
resembles. It has a short centrum with ends which are slightly convex,
a rudimentary arch which is triangular, and rudimentary oblique, trans-
verse, and superior spinous processes. The processes are represented, but
are still more rudimentary, in the second and third bones. In the fourth
bone the arch is incomplete, as the lamina? do not meet. As we proceed
backwards the pedicles diminish in size and disappear, until in the last few
members of the series the vertebrae are simply represented by constricted
rods of bone with convex extremities.
Fractures of these bones are not common in the horse. They occur
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iSo THE SURGICAL ANATOMY OF THE HORSE
most frequently in the ox. It was observed, when dealing with luxation
of the sacro-iliac joint (Vol. III.), how the sacrum was sometimes displaced
downwards in colliery ponies as a result of a fall of the roof. From a
similar cause the sacrum is sometimes fractured. Displacement is always
in the downward direction, there is a marked hollow over the region of
the croup, the internal angles of the ilia stand out more prominently, and
in very serious cases there is inability to defalcate, or even micturate. The
hind limbs may be paralyzed. Diagnosis may be confirmed by careful
rectal exploration. Serious haemorrhage into the spinal canal is a common
complication in such cases, owing to injury to the ascending branches from
the lateral sacral artery, which pass upwards through the inferior sacral
foramina. Fracture through the first or second coccygeal vertebra may lead
to paralysis of the rectum, bladder, and even the hind limbs, when there is
extensive haemorrhage into the neural canal.
When the sacrum is fractured, a favourable prognosis can usually be
given in those cases in which the animal retains the ability to stand. When
symptoms of paralysis are presented, the cases are much less hopeful.
Paralysis of the bladder necessitates the frequent passage of the catheter.
In cases of uncomplicated fracture of the sacrum, treatment should follow
general principles, rest being provided for the part, and the animal placed
in slings. If there are complications, treatment is rarely successful, and
the best course is to advise slaughter.
In simple fractures of the tail a splint can be readily applied. If the
fracture be compound, or there is severe bruising of the part, amputation is
the best course to adopt.
OPERATIONS ON THE TAIL—CAUDAL MYOTOMY
Before commencing an operation on the tail, the position of the
principal vessels and nerves should be studied. This is best noted in a
transverse section, such as is represented in Plate XV. In the centre
of the Plate is seen a section of one of the caudal vertebrae, which is
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OPERATIONS ON THE TAIL—CAUDAL MYOTOMY 151
almost circular. There are two small arteries on either side, the superior
and inferior lateral coccygeals. The largest artery is placed inferiorly in
the median line. This is the middle coccygeal artery. Superficial and
deep veins are placed superiorly, laterally, and inferiorly, and some are of
considerable size. The muscles are arranged in a kind of circle around
the bone, and are bound down in position by dense fascia. On either side
the median line above these there are two fairly thick bands. These
are the sacro-coccygeus superior or erector coccygis muscles. Laterally
are the curvator coccygis and inferiorly the compressor coccygis or
depressor muscles.
The practice of dividing the depressor muscles with the object of
causing the animal to carry its tail higher, an operation commonly known
as " nicking," is to be condemned. There are, however, some cases of
curvature of the tail in the correction of which the operation of
myotomy might be justified. The seat of the incision depends upon the
nature of the curvature. Curvature is usually due to unequal develop-
ment of a member of one of the pairs of caudal muscles. Most frequently
one or other of the erector coccygis muscles is affected. Sometimes it is
one of the depressors. In the former case the incision is made longi-
tudinally in the groove on that side of the tail on which is the shorter of
the two unequal muscles (the operation consists in dividing this muscle).
Dissect along the lower border of the erector muscle, towards the
bone. The superior lateral coccygeal artery should be pressed down-
wards with a probe, and the bistoury introduced flatwise above the
artery. Its cutting edge is now directed towards the muscle, which is
severed as the instrument is withdrawn. Care must be taken not to
lacerate the skin, and also to see that the fascia and muscle are divided.
In dividing the depressor muscle, the incision should be made inferiorly
and in the middle line. This will enable the operator to find the middle
coccygeal artery and its accompanying veins, which can be pressed aside,
and thus avoided, during the section of the muscle. A pad of tow or
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152 THE SURGICAL ANATOMY OF THE HORSE
cotton wool sprinkled with dry dressing is now applied to the wound, and
the tail bandaged.
Local anaesthesia is usually sufficiently effective in these cases.
AMPUTATION OF THE TAIL
It has already been stated that this operation is indicated in certain
severe cases of fracture of the caudal vertebras. It is also performed in the
treatment of malignant growths and other diseases of the tail which are
incurable.
The animal is cast and placed under a general anaesthetic. The hair
is shaved from the area of operation, which is cleansed thoroughly and
disinfected. At the base of the tail a tourniquet or elastic bandage is
applied, the hair here being turned upwards beneath the tourniquet. The
operator should now endeavour to locate a joint above the diseased
portion. Having done this, two oblique incisions are made on either
side. One of the incisions passes backwards and upwards, and the other
backwards and downwards, so that the pairs of incisions meet above and
below. Two V-shaped flaps of skin are thus mapped out, one above, the
other below. They are both reflected towards the root of the tail. The
joint can now be felt more readily, and here an incision should be carried
around the tail through the muscles. The lateral and inferior coccygeal
arteries should be seized with the forceps and closed. It may be
necessary to ligature. The joint is now disarticulated, so that the stump
is left with two projecting V-shaped flaps of skin. The apices of
the latter are brought together over the stump and sutured. Sutures are
now inserted in the edges of the flaps, so that the latter effectively enclose
the end of the stump. The end should now be enclosed in tow, with a
plentiful application of dry dressing, and this is kept in position by releas-
ing the hair tied back under the bandage or tourniquet, and tying it around
the tow. The hair is then whipped around with thick thread. Failing
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THE SPINAL CORD                                   153
this method, the tow should be kept in position by means of a bandage.
The usual consecutive treatment is adopted.
THE SPINAL CORD
On opening the spinal canal by sawing away the neural arches,
the dura mater will be exposed. This is the outermost of the three
membranes which enclose the spinal cord. It is a tough fibrous tube
extending from the foramen magnum to the coccygeal region. It forms
a loose envelope. Slender processes attach it to the superior common
ligament. The tube is not of uniform diameter throughout, for at the
base of the neck and in the lumbar region it becomes widely dilated.
Within the dura mater is the arachnoid membrane. This is arranged
in two layers, after the manner of serous membranes, and it is a much
more delicate structure than the dura mater. Between its parietal
and visceral layers is the subdural space, which contains just sufficient
fluid to lubricate the parts.- The quantity of this fluid varies, and its
action is alkaline. The parietal and visceral layers become continuous
around the roots of the spinal nerves as the latter pass out to pierce the
dura mater. The pia mater is the membrane next the cord, to which it
forms a tightly-fitting tunic. It is the vascular membrane, and is made
up of areolar tissue, in which the vessels split up before penetrating the
cord. Laterally it sends out processes connecting it with the dura mater,
and forming what is known as the ligamentum denticulatum. These
processes are attached to the dura mater between the points of exit of the
superior and inferior roots of the spinal nerves. Between the arachnoid
and pia mater is the subarachnoid space, which is broken up by reticulate
fibres passing from the arachnoid to be attached to the pia mater. In
this space is the cerebro-spinal fluid.
The cord itself begins at the foramen magnum, where it is continuous
with the medulla oblongata, and it extends backwards to the middle of
u
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154 THE SURGICAL ANATOMY OF THE HORSE
the sacral region, where it ends in a conical process known as the conus
medullaris. It is not of uniform thickness throughout, for there are two
portions which are much thicker than the rest. One is known as the
cervical enlargement, and it extends from the lower cervical region to the
second dorsal vertebra, behind which the cord again contracts. From
this enlargement the nerves of the fore limb are detached. The other
enlargement is in the lumbar region, and from it the roots of the nerves,
which supply the hind limb are derived. Beyond the conus medullaris
the end of the dura mater projects, and its posterior end forms the filum
terminale. On transverse section the cord is seen to be slightly flattened
from above to below. It is divided into two symmetrical halves by a
superior median fissure and an inferior median fissure, both running
longitudinally. The former is occupied by neuroglia. It is very
narrow, and extends into the cord along the middle line of its superior
surface. The inferior fissure is a cleft in the middle line inferiorly, into
which the pia mater projects. A faint depression runs along the lateral
surface, where the superior roots of the spinal nerves emerge. This is
referred to as the supero-lateral fissure.
The two median fissures do not meet, since they are separated by a bridge
of tissue forming the grey and white commissures which connect the two
halves of the cord. The grey commissure is the upper, and in its centre
is the central canal of the cord. This canal opens anteriorly into the
fourth ventricle of the brain, and extends backwards throughout the
length of the cord. The white commissure is thinner than the grey, and
it stretches across the cord just above the inferior median fissure. The
grey nerve tissue in the cord forms a crescent-like mass, placed in the
interior of the white matter in each half. The convex surface of the
crescent is directed inwards. The extremities of the grey matter are
termed the superior and inferior horns. The former is pointed, and
approaches the surface of the cord at the supero-lateral fissure. The
inferior horn, which is broader and more blunt, lies at a greater distance
from the surface. From the horns the bundles of nerve fibres are
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THE SPINAL CORD
!55
detached which form the superior and inferior roots of the spinal nerves.
In addition to nerve cells, the grey matter consists of nerve fibres, some of
which have medullary sheaths, and nerve fibrillar The white matter
surrounds the crescent of grey matter in each half. The grey matter in
each half divides the white into three columns—namely, a superior or
dorsal column, placed between the superior median fissure and the
superior horn; an inferior or ventral column, between the inferior median
fissure and the inferior horn ; and a median or lateral column, between the
two horns. The superior column is further divided into two portions,
the inner of which forms the column of Goll, the outer the column of
Burdach. In man there is a further division of the white matter into
columns which form definite conducting paths. The white matter also
contains medullated nerve fibres, and its base, as also that of the grey
matter, is a delicate connective tissue known as neuroglia. The average
length of the cord is about six and a half feet, the average weight
approximately nine ounces.
The cord is supplied with blood by the middle spinal artery, which is
formed by the anastomosis of the posterior divisions of the cerebro-spinal
arteries; by branches of the vertebral arteries in the neck, of the inter-
costal arteries in the back, and of the lumbar and lateral sacral arteries in
the lumbar and sacral regions respectively. Blood from the cord passes
to a plexus of veins on its surface, and this is drained by two large veins
which run one on either edge of the superior common ligament. These
in turn empty themselves into vessels which pass out through the
intervertebral foramina to join the vertebral, intercostal, lumbar, or lateral
sacral veins.
From the cord forty-two or forty-three pairs of spinal nerves are
given off—eight cervical, eighteen dorsal, six lumbar, five sacral, and five
or six coccygeal. With the exception of the first, which leaves the canal
by the antero-external foramen of the atlas, they are named according to
the number of the vertebra behind which each emerges. Each nerve
has two roots, which leave the horns of grey matter as described. The
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156 THE SURGICAL ANATOMY OF THE HORSE
filaments of the superior root, after piercing the dura mater, converge
towards the intervertebral foramen, forming a cord upon which there is
superposed a reddish oval ganglion. This is the sensory or ganglionic
root.
The fibres detached from the inferior horn of grey matter pass out
through the dura mater, and form the inferior root of the nerve, which is
also called the motor or aganglionic root, and which also converges to the
intervertebral foramen, where its fibres become commingled with those of
the superior root beyond the position of the ganglion. A short common
trunk is thus formed, which almost immediately splits into two portions,
each containing fibres derived from both the superior and inferior roots,
and each being, therefore, sensory-motor. These two portions are known
as the superior and inferior primary divisions. The series of superior
primary divisions, after leaving the intervertebral foramina, speaking
generally, supply the skin and muscles above the foramina, and the inferior
divisions the corresponding parts below. From the short common trunk
referred to, a small filament passes back into the spinal canal to be
distributed to the bones and vessels, and in the cervical region small root-
lets spring from the sides of the cord to form the cervical contribution to
the spinal accessory nerve.
In the region of the neck the nerves pass out of the spinal canal almost
at right angles to the cord. In the dorsal region they incline slightly
backwards to the foramina, by which they emerge. The inclination
increases progressively in the lumbar, sacral, and coccygeal regions, so that
the sacral nerves are detached from the cord in the lumbar region, and the
coccygeal nerves leave the end of the cord, which is in the middle sacral
region. The similarity between the end of the cord, and the nerves leaving
it, to the end of a horse's tail led to the name cauda equina being given to it.
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INJURIES TO THE SPINAL CORD—PARAPLEGIA 157
INJURIES TO THE SPINAL CORD—PARAPLEGIA
In the horse the spinal cord is frequently injured. This is not
surprising when it is considered what diverse uses the animal is subjected
to, and the violent and sudden exertion which it is frequently called upon
to perform. Paraplegia is the technical term applied to " double-sided
paralysis," and, although some cases arise as a result of injury to the brain,
most are due to injury to the spinal cord. Obviously, the symptoms
presented are subject to a considerable degree of variation, depending upon
the nature and degree of the injury, its situation in the cord, the muscles
controlled by nerves which are detached from the cord posterior to the
seat of injury, etc. In the present state of knowledge, there is very
little definite information concerning a number of these points, and many
peculiar lamenesses are attributed to spinal injury simply for the want of
some better explanation.
That the subject is one in which there is urgent need for research
work will not be denied ; but one of the greatest difficulties to be overcome
is the securing of sufficient suitable material for research, in order that
slowly-proceeding affections may be observed during the various
stages in their development.
Perhaps the best method of classifying these various paralyses is that
adopted by Moller, who divides them into—
1. Complete paraplegia, resulting from injuries to or pressure upon the
cord, as a result of fracture in the dorsal, lumbar, or anterior sacral regions.
It also occurs as a result of inflammation of the substance of the cord as a
sequel to some other disease, such as influenza or strangles, and as a symptom
of sunstroke. Idiopathic inflammation of the cord sometimes occurs, and
has been observed by Friedberger, Dieckerhoff, and others. Tumours in
the spinal canal exert pressure on the cord, and bring about complete
paraplegia. Hertwig had a case in which the condition was due to a
melanoma. Paraplegia is also a part of general paralysis. Changes in the
nerves, muscles, or vessels, of the hind limb may also lead to it.
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158 THE SURGICAL ANATOMY OF THE HORSE
2. Incomplete chronic paraplegia has been applied to most cases in
which the functions of the hind limbs have been disturbed, so that the
movements are irregular and the muscles do not work harmoniously. It
is apparent that these symptoms may be due to a variety of causes, and
are not characteristic of any one particular disease. Wolff had cases in
which the hind legs were dragged after fracture of the coccygeal vertebras.
In these cases it will be understood, from our description of the anatomy
of the cord, the changes must have extended for some distance forward to
the cord from the seat of the original injury. According to M oiler,
French opinion is inclined to the view that paraplegia is generally the
result of an injury to the vertebrae. In some cases there is pressure on the
cord by exostoses which have formed in the spinal canal. Similarly, pressure
may be exerted by tumours or cysts in the canal. It has been reported to
be the seat of carcinomata. In these cases the symptoms, as would be
expected, make their appearance gradually, and the condition is pro-
gressive. In some cases, however, the symptoms present themselves
suddenly, as in one case in which they were found to be due to the
development of an osteo-sarcoma.
When the hind quarters are completely paralyzed, the animal is down,
and unable to rise or stand if raised. The anterior crural nerves are
detached from the anterior portion of the lumbo-sacral plexus (see
Vol. III.). When the injury is behind the origin of their roots, their
function is preserved, so that in these cases the animal can fix the stifle
and can stand, although unable to walk. There is complete loss of reflex
irritability when the cord is injured at or behind the lumbar region. In
addition, as already stated, these symptoms may be accompanied by
paralysis of the bladder, rectum, and also the tail. When the vertebrae
are fractured, it may be possible to detect crepitation. Sometimes dis-
placed pieces of bone can be felt.
In what is termed true incomplete or spinal paralysis, the cause must
be sought in the spinal canal. When due to inflammatory processes in
the cord and its meninges, the movements are irregular, the animal loses
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INJURIES TO THE SPINAL CORD—PARAPLEGIA 159
strength and tires quickly. The limbs can support weight, but render
little assistance in making progress. If the animal be made to walk, the
hind limbs " make irregular ataxic movements." The toe is dragged, and
not lifted clearly from the ground. Later the foot is raised to an abnormal
height, and set down with a sudden jerk. Sometimes the foot describes
a semicircle by swinging outwards, and there is crossing of the feet
during progression. As a rule, sensibility is not lost and the muscles
do not atrophy. In spurious incomplete paraplegia the cause is outside
the canal, such, for instance, as in the vertebra or intervertebral discs.
Commonly it is not a disease of nerve tissue, but is due to derangement
of the mechanical efficiency of the muscles as a result of overwork.
In complete paraplegia in the horse, prognosis is usually unfavourable,
and the cases are generally hopeless. In incomplete paraplegia prognosis
depends upon the cause. When due to degenerative changes in the
nerve tissues, they are usually hopeless, and the same may be said of
those conditions which tend to become gradually worse. But, as we
have already stated, in many of these conditions our knowledge is most
indefinite, and they remain to a great degree in obscurity.
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CHAPTER IV
THE UROGENITAL ORGANS
THE URINARY ORGANS
The Kidneys, Ureters, and Bladder
The Kidneys are the glands which secrete the urine. They are placed
beneath the roof of the abdominal cavity under the psoae muscles. In
colour they are reddish-brown. Each possesses two surfaces, two borders,
and two extremities.
In shape the right kidney has been aptly compared to the heart ot
playing cards. With regard to the skeleton, it may be said to lie beneath
the last three ribs and part of the first lumbar transverse process. Its
superior surface is convex. It is related to the diaphragm in front and
the psoas muscles behind. The inferior surface is almost flat, and is related
to the liver in front, to the pancreas, the cascum, and inwardly to the
right adrenal body. The inner border is the thicker, and is convex. It
is related to the posterior vena cava and the right adrenal body. The
hilus is a deep indentation placed near the middle of this border, and this
is where the renal artery enters the kidney, and the renal vein and
ureter leave it. The outer border is also convex, and around it the
duodenum curves. The anterior and posterior ends are rounded. The
former is the thicker, and is accommodated in a depression on the posterior
surface of the liver.
The left kidney differs very much in shape from the right. It is
more elongated, is not so wide, and is usually referred to as being bean-
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THE URINARY ORGANS
161
shaped. It is placed farther back, extending from the level of the last
rib anteriorly to the third lumbar transverse process posteriorly. Its
superior face is convex, and for the greater part related to the psoas
muscles. Anteriorly a small portion is related to the diaphragm, and
outwardly it touches the spleen. The inferior surface is also convex. It
is related to the duodenum, floating colon, and the head of the pancreas,
but the greater portion of this surface is covered by peritoneum. The
left adrenal body is also related to this surface. The inner border is thick
and almost straight. The hilus is placed near its middle. This border
is related to the posterior aorta, left adrenal body, and the left ureter.
The outer border is convex and related to the spleen. Its anterior and
posterior borders are rounded. The former is related to the pancreas and
vessels of the spleen. The posterior end is usually much the larger,
and is also rounded.
The average weight of the right kidney is about a pound and a half,
the left being from one to two ounces lighter.
The Suprarenal or Adrenal Bodies.—There are two of these ductless
bodies—right and left. They are of a slate-brown colour, and are flattened.
Each is from one to two ounces in weight. That on the right side is
placed between the anterior portion of the inner border of the right
kidney and the posterior vena cava. The left is similarly placed between
the left kidney and the posterior aorta. They are highly vascular, and
have a rich nerve-supply.
The Ureters are the ducts which convey the urine from the kidneys
to the bladder. The left begins at the hilus, and, passing backwards and
inwards over the inferior surface of the left kidney, becomes placed
alongside the posterior aorta and under the psoas parvus muscle. The
spermatic artery, after leaving the aorta, crosses the ureter obliquely.
The latter now curves outwards, passing across the circumflex-iliac artery
and the artery to the cord. It follows for a short distance the external
iliac artery, and then passes across the vessel to enter the pelvis. Here it
runs backwards and slightly downwards over the supero-lateral part of the
X
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162 THE SURGICAL ANATOMY OF THE HORSE
bladder, and curving inwards it perforates the wall of the latter organ a
little in front of the neck. The right ureter in the abdominal cavity is
related to the posterior vena cava. In the male the ureter during its
course in the pelvis also crosses the vas deferens.
The tube has an average diameter of about one-third of an inch.
The Urinary Bladder.—When distended, the bladder is an ovoid sac
placed for the greater part in the pelvic cavity, but its anterior broad
end, fundus or vertex, projects into the cavity of the abdomen "beyond
the pelvic brim. When empty it lies entirely within the pelvis, on the
superior surface of the pubic bones. Superiorly it is related in the male
to the rectum, urogenital fold, vasa deferentia, vesiculas seminales, and
the prostate gland; in the female to the uterus and vagina. The anterior
end of the distended bladder is related to the pelvic flexure of the large
colon, the floating colon, and coils of the small intestine. It is held in
position by folds of peritoneum, known as the ligaments of the bladder.
Where the peritoneum is reflected from the bladder on to the floor of the
pelvis and abdomen, it forms a fold known as the middle ligament. This
is most extensive in the new-born animal. Connecting each side of the
bladder with the corresponding lateral wall of the pelvis is the lateral
ligament. This contains at its free-edge the remains of the umbilical
artery of the foetus, which in the adult is perforate only for a short
distance. The posterior portion of the bladder, which is not covered by
peritoneum, is attached to the neighbouring structures by a quantity of
loose connective tissue containing an admixture of fat. Whilst the
anterior part is freely movable, this part occupies a fixed position.
Part of the wall, as stated, possesses a serous layer. Beneath this is
the muscular layer, the fibres of which have not a definite arrangement,
but form a kind of network. Fibres run longitudinally above and below,
and at the neck of the organ they form a sphincter. The internal lining,
or mucous coat, is thin and pale. The ureters pierce the walls obliquely,
and their internal orifices are placed near the neck posteriorly, about an
inch apart. The manner in which the ureter pierces the wall effectively
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THE URINARY ORGANS                              163
prevents the return of urine from the bladder to the ureter. The orifice
of the urethra is about an inch and a half behind the ureteral openings,
and between these three orifices there is a triangular area known as the
trigonum vesicas, in which the mucous lining differs from that of the rest
of the bladder and is not thrown into folds.
The bladder derives its blood-supply from branches of the vesico-
prostatic, obturator and umbilical arteries. Its nerve-supply comes from
the pelvic plexus. This latter is an intricate network of nerves on the
side of the rectum. It receives contributions from the posterior mesen-
teric plexus of the sympathetic and from the inferior sacral nerves. It
also distributes branches to the rectum, the prostate gland, and vesicula
seminalis in the male, and to the vagina and uterus in the female.
The capacity of the bladder is from three to four quarts.
The Urethra. — This differs considerably in the male and female.
In the former it is a long tube which extends from the neck of the
bladder to the anterior end of the penis. It is thus divided into pelvic
and extrapelvic portions. The former is from four to five inches long.
It has a diameter of from one to two inches. It is greatest behind the
prostate gland, and narrows down where it passes between Cowper's
glands, near the ischial arch. From the arch the remaining portion has
a diameter of one-fourth to five-eighths of an inch. Just behind the glans
penis there is a dilatation, and beyond this the tube again contracts.
Anteriorly it projects freely for a short distance in front of the glans penis.
The intrapelvic division consists of what are generally referred to as
prostatic and membranous portions. The former is very small in the
horse, and simply consists of that part which is surrounded by the prostate
gland and which is continuous with the neck of the bladder. The
membranous portion extends backwards to the ischial arch, where it
bends at an acute angle to become continuous with the spongy
portion.
In the mare the urethra has a length of only about two inches. It
lies on the floor of the pelvis, and into it the finger can be readily intro-
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164 THE SURGICAL ANATOMY OF THE HORSE
duced. It is capable, however, of a considerable degree of distension.
Superiorly it is attached to the wall of the vagina.
In the male the mucous membrane contains many elastic fibres.
Outside this are circular muscle fibres, which are enveloped again by
erectile tissue continuous with the corpus spongiosum. Surrounding
this in the intrapelvic portion is the urethral or Wilson's muscle, and in
the extrapelvic portion the accelerator urinas muscle, the fibres of which
at the root of the penis are arranged circularly around the corpus
spongiosum. Lower down they arise from a median raphe, and curve
upwards over the sides of the corpus spongiosum to the tunica albuginea
of the corpus cavernosum.
URINARY CALCULI—OPERATIONS FOR REMOVAL
Renal calculi are by no means common in the horse, and their
presence is usually detected post mortem, owing to the great difficulty
in effecting a positive diagnosis during life. Moreover, since the kidney,
in the present state of our knowledge of abdominal surgery in the horse,
is practically in an inoperable position, the condition calls for no further
reference here. Occasionally small calculi pass from the kidney down
the ureter into the bladder. These in rare cases become arrested in the
ureter and block its lumen. The points at which such an obstruction is
most likely to occur are where the ureter is passing into the pelvic cavity
and where it pierces the wall of the bladder. By exploration through
the rectum, the distended ureter can be felt. Practically the only course
open in such a case is to endeavour to manipulate the calculus downwards
into the bladder.
Calculi in the bladder, or vesical calculi, can usually be felt by passing
the finger up the urethra in the mare. In the male their presence is
best ascertained by rectal exploration. There are in addition the usual
clinical symptoms. The only effective method of treatment is to remove
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URINARY CALCULI—OPERATIONS FOR REMOVAL 165
the calculus surgically. In the mare, calculi of considerable size can be
removed with a pair of forceps introduced through the urethra. It has
been stated that the tube is capable of a great degree of distension. This
will be facilitated if the mare be placed under a general anaesthetic. The
forceps must be well lubricated and introduced patiently. The calculus
is guided between the jaws of the instrument by a hand passed up the
rectum. Care must be taken, before withdrawing the forceps with its
contained calculus, to rotate it, in order to make certain that no part of
the wall of the bladder is included, and that the calculus is free from
the wall.
In the removal of vesical calculi in the male, the operation of lithotomy
is usually performed. The animal is cast and placed under a general
anaesthetic. Great care must be taken when casting, and plenty of
bedding must be provided. There is a danger in casting an animal with
a distended bladder. It will usually be found most convenient to turn the
animal on its back. The rectum is emptied, the hind limbs drawn well
forward, and the prepuce, penis, and perineal region, thoroughly cleansed.
Urethrotomy is now performed, to gain entrance to the urethra. The penis
is withdrawn, and held by an assistant. It is now advisable to distend the
urethra in order that its course may be clearly made out. There are
several ways of effecting this—namely, by injections, by the introduction of
a catheter or a grooved staff. Axe used a staff. The groove in the staff is
directed towards the raphe in the skin of the perineum, and the instrument
is guided around the ischial arch. A hand is placed in the rectum
to direct the staff into the bladder. The skin is now made tense with the
thumb and fingers of the left hand, and an incision made through it,
extending from the ischial arch to within an inch of the anus. The
incision is made in the middle line, and passes through the skin and
perineal fascia. The retractor penis muscle is now exposed. This can
without difficulty be pushed aside, as in the Plate, or a longitudinal
incision made into it. The incision is next carried through the
accelerator urinae muscle, corpus spongiosum, and the wall of the urethra.
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166 THE SURGICAL ANATOMY OF THE HORSE
A small puncture is first made with the point of the scalpel, and the posi-
tion of the groove in the staff" ascertained. The last incision is then made
by utilizing this groove after the manner of that in an ordinary director.
The staff is now withdrawn, and a sound introduced to ascertain the size
and condition of the calculus. It is advisable to prevent the urine from
escaping as much as possible, for, by preventing collapse of the bladder
wall, the removal of the calculus is facilitated. Subsequent procedure
depends upon the size of the calculus. It is surprising how widely the
urethral orifice can be dilated with patience. It has been reported that
the hand has been introduced through it into the bladder without incising
the constrictor fibres. When necessary to make a second incision, this is
done by introducing a bistoury into the bladder along the grooved
director. The constrictor fibres are incised just behind the neck of the
bladder during the withdrawal of the instrument. Great care must be
taken not to injure the rectum. The forceps are now warmed, oiled, and
passed into the bladder with the jaws closed. Separating the jaws, the
calculus is manipulated between them by means of the hand in the
rectum. The operator should take the precaution to rotate the instru-
ment before withdrawal, in order to keep clear of the bladder wall. A
careful examination is made by rectal exploration for other calculi or
gravel. Small calculi or gravel may be removed by a lithotomy scoop
introduced in a similar manner. It is frequently necessary to wash out
the bladder with a weak and lukewarm antiseptic solution.
If the calculus be so large that it cannot be removed, the operation of
lithotrity is performed. An instrument known as a lithotrite is introduced,
and with it the calculus is crushed. The portions are then removed with
the forceps or scoop.
Regarding the treatment of the wound, some insert a number of
simple interrupted sutures in the wall of the urethra. Others close by means
of a modified kind of Lembert's suture. The wound may be, however,
and frequently is, left unstitched. The tail is tied to one side, and the
wound dressed with antiseptics. It heals in from twelve to fourteen days.
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PUNCTIO VESICAE                                    167
Calculi are sometimes arrested in the urethra. In these cases removal
is not difficult. In rare cases they are found near the glans penis, when
they can usually be removed with the hand or a pair of ordinary forceps.
Most frequently, in the horse, the calculus is found near the ischial arch.
The writer has encountered them in this situation attaining the size of a
walnut. As a rule it is not necessary to cast the animal, and the opera-
tion can be performed in stocks. After the usual preparatory treatment, a
catheter is passed, and urethrotomy performed over the seat of the
calculus. It is important that the incision in the wall of the urethra be
not larger than will permit the withdrawal through it of the calculus.
In some cases the stone is easily removed with the fingers. In others
forceps are necessary. After its removal urine should escape in quantity.
If it does not, a careful search should be made for other calculi. The
treatment of the wound is similar to that already described.
PUNCTIO VESICA
This is the name given to the operation of puncturing the bladder to
afford relief in cases where, from obstruction or some other cause, there
is retention of urine, the bladder becomes unduly distended, and there is
a danger of rupture. The operation is commonly performed in the
human subject, and in carnivora it is frequently practised with very little
risk, the puncture being made through the posterior portion of the
abdominal wall. In the horse, however, the bladder when distended
passes downwards and forwards, but it does not reach the floor of the
abdomen. Another method is to puncture through the rectum. This
is frequently adopted when operating on fat cattle almost ready for
slaughter. Obviously, there is great risk of the bladder becoming infected
and inflamed. The best method in the horse is that known as punctio
perinealis. An incision is made in the skin to the side of the urethra,
just below the anus. The fingers are then insinuated forwards by
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168 THE SURGICAL ANATOMY OF THE HORSE
breaking down the connective tissue. In this process the handle of the
scalpel is frequently useful. On arriving at the wall of the bladder,
which when distended can be readily felt, a straight trocar is introduced.
The point is thrust forwards through the bladder wall with the canula.
The stilette is then withdrawn, and the urine escapes through the canula,
the latter being now pressed slightly forwards. If it is not considered
necessary that the operation should be repeated, the trocar and canula
should now be withdrawn. The wound is simply kept clean and dusted
over with dry dressing ; it is not necessary to suture. If it is considered
desirable, the canula can without much risk be allowed to remain in
position for several hours, or even two or three days.
PROLAPSE AND INVERSION OF THE BLADDER
These are conditions encountered in the female. The bladder is
occasionally displaced backwards during parturition, and projects through
a rent in the inferior wall of the vagina. This is known as prolapse of
the bladder. It is rare in mares, and is most frequently observed in the
cow and sow. It is not difficult to diagnose, since, if a careful search be
made, the rent in the vagina can be felt. The bladder in this condition
is covered by serous membrane. The condition must not be confused
with inversion of the bladder, in which the bladder is simply turned
inside out and projects through the urethral orifice. This is much more
commonly encountered in mares as a complication through severe straining
during parturition. It will be obvious that anything which dilates the
urethral orifice will predispose to inversion. In this condition the swelling,
which may protrude beyond the vulva or may simply extend into the
vagina, is not covered by peritoneum. It should be examined carefully.
If inversion is suspected, the surface of the swelling will correspond to
the description given of the mucous membrane of the bladder. Before
finally deciding, the ureteral orifices should be found, and the area known
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PROLAPSE AND INVERSION OF THE BLADDER 169
as the trigone located. It will be observed that urine will pass out
of the orifices when the part is compressed. The swelling contains
peritoneal fluid.
It is important to distinguish between prolapse and inversion, because
in the case of the former an unfavourable prognosis has usually to be
given. There is communication with the peritoneal cavity, and septic
peritonitis with a fatal termination is a common complication. It is only
when the case is seen very early, and before any changes have occurred
in the serous covering of the swelling, that an attempt to replace the
organ can be made with any hope of successful results. If the surface
appears normal, it should be gently washed over with a warm and weak
antiseptic solution, and the organ manipulated back through the opening
in the vaginal wall. Occasional injections of warm solutions will assist in
preventing a recurrence. If the opening in the vaginal wall be far back
and near the vulva, it is possible to close it by sutures.
In a case of inversion, the object is to replace the bladder before
changes occur in the mucous membrane. A twitch should be applied
and the hind quarters raised. The exposed membrane is cleansed with
warm antiseptic solutions. It is then compressed, to drive forward the
peritoneal fluid. The next step is to manipulate it back through the
urethral orifice. This can sometimes be done with the fingers. Some
use a blunt instrument with a rounded surface. The greater the difficulty
in replacement, the less the likelihood of a recurrence as a rule.
Occasional injections of warm antiseptic solutions will tend to allay
irritation and prevent a recurrence. Such injections are also said to bring
about a contraction of the urethral orifice.
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lyo THE SURGICAL ANATOMY OF THE HORSE
AMPUTATION OF THE BLADDER
When the bladder has been inverted for a considerable time, and
necrotic changes have taken place in its mucous membrane, return of the
viscus is contra-indicated. Practically the only course open to the operator
under such circumstances is to amputate the bladder. This operation,
although it removes the natural reservoir, and in consequence urine dribbles
from the vagina, does not render working horses useless, and for this reason
Moller claims that it is justified.
The usual method of amputation is by ligation, and there are many
different kinds of ligatures used. Whatever method is adopted, a point
to be observed is that the ligature must be kept behind the orifices of the
ureters. It has a tendency to slip forwards, and this must be prevented.
Moller prefers the elastic ligature, and utilizes a piece of tape in a very
ingenious manner to keep the ligature in position. The free ends of the
tape are passed forwards from the swelling, one above and the other
below the neck. The ligature is then applied around the neck and
tapes. The ends of the latter are now carried backwards and tied behind
the broad end of the swelling. It will thus be seen that the tape will
effectively prevent the ligature from slipping forwards. The bladder is
allowed to slough away.
TUMOURS IN THE BLADDER
Tumours in the bladder are not uncommon in the horse. Some are
benign, such as fibromata and lipomata. Others, such as carcinomata,
are malignant. Barnick, quoted by Moller, discovered a tumour in the
bladder which attained enormous dimensions, being twice as large as a
man's head. The symptoms which are presented are not unlike those
in cystic calculi. As the growth develops, urine is passed more frequently.
It is turbid, and frequently contains blood-clots and pus. The best means
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URETHRAL FISTULA AND STRICTURE              171
of detecting their presence is by rectal or vaginal exploration. Palpation
will reveal the presence of an abnormal growth, which will be found to
have a fixed position, and is readily distinguished from a calculus by its
softer consistency. If the growth be near the neck of the bladder, there
is dysuria. As a rule it is advisable to give an unfavourable prognosis.
The successful removal of a tumour from the bladder is a matter of
considerable difficulty. Those attended with most successful results are
the non-malignant growths which are more or less pedunculated, and
which are situate near the neck of the bladder. In the mare these can
frequently be removed with a wire or chain ecraseur introduced after
dilatation of the urethra.
In the male, urethrotomy must first be performed. The subsequent
treatment is as in lithotomy.
URETHRAL FISTULA AND STRICTURE
Cases in the horse in which the urethra is damaged, except as a
complication to some operation, are rare. Occasionally the mucous
membrane is injured by foreign bodies such as awns of wheat gaining
access and working upwards. Moller quotes a case reported by Bluhm
in which an oat-head four inches long worked its way up the urethra
and set up inflammation. Stricture sometimes follows as a result of such
injury, or it may result from an injury due to the careless introduction of
the catheter. Most frequently, however, it occurs after such operations
as urethrotomy and amputation of the penis. Wounds in which cicatricial
tissue forms commonly lead to stricture. It is a progressive condition
which, in the horse, is serious. The object should be, then, in all such
cases, to secure quick healing. Should it be decided to suture any wound
of the urethra, the greatest care should be exercised during the insertion
of the sutures. It is usual, as in the human subject, to pass bougies
or sounds of varying diameters to dilate forcibly the constricted portion.
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172         THE SURGICAL ANATOMY OF THE HORSE
But a cure is rarely permanent, and the condition has a marked tendency
to recur. As a precaution against stricture formation after an operation,
some pass at intervals the catheter, which has been carefully smeared with
an antiseptic lubricant.
Occasionally operation wounds in urethrotomy are not successfully
closed, with the result that a urethral fistula is formed. This condition
is difficult to treat and close effectively without the subsequent formation
of a stricture. The method of closure for which the greatest success is
claimed, and which is now most frequently adopted, is to sear carefully
the edges of the opening into the wall of the urethra, and then approximate
them by means of a number of fine closely-set interrupted sutures.
THE MALE GENITAL ORGANS
The Scrotum.—This is the pouch in which the testicles and lower
portions of the spermatic cords are suspended. It consists of a number of
layers. Most outwardly is the skin, which is here a modified portion of
the surrounding integument. Running longitudinally is a median raphe,
which extends forwards on to the prepuce and backwards to the perineum.
This skin is thinner than that of the surrounding parts. It is smooth and
moist to the touch, owing to the secretion of numerous sebaceous glands
which it contains. Scattered over it are numerous short fine hairs. It
forms a single sac for the two testicles. Beneath the skin is the
dartos, which is a reddish-yellow layer of connective tissue, containing
many elastic and involuntary muscle fibres. Unlike the preceding layer,
the dartos forms two pouches, one for each testicle. In the median line
the two pouches come into apposition and form the septum scroti.
Above, these two layers separate, and between them the penis passes.
When this layer contracts, the scrotum becomes wrinkled. After
incising the dartos, it is usual to describe three successive layers termed
respectively the spermatic fascia, the cremasteric layer, and the
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THE MALE GENITAL ORGANS
J73
infundibuliform fascia. Little importance is now attached to this division.
The separate layers are represented in Plate XVI. Lastly, we have
the tunica vaginalis, which has already been described (see Inguinal
Canal).
The Spermatic Cord.—Having cut through the layers of the scrotum, if
the testicle be withdrawn through the opening, the spermatic cord which
extends from the testicle up the inguinal canal will be exposed. A good
view of the interior of the lower portion of the canal may be obtained by
applying traction to the cord, hooking the testicle well forward, hooking
aside the plexus of large veins which ramify here, and drawing slightly
backwards the posterior border of the external abdominal ring. Such a
view is represented in Plate X., a careful study of which will
make evident the borders of the ring, the boundaries of the canal, and
most of the contents of the latter. The cord begins at the internal
inguinal ring, where the following structures enter into its formation :
(i) The spermatic artery, which is extremely convoluted. (2) The
spermatic veins, forming the so-called pampiniform plexus. (3) The
lymphatics and sympathetic nerves. The foregoing structures are placed
in the anterior portion of the cord. They are united by connective
tissue, throughout which fibres of the cremaster internus run. Together
they form a distinctly cord-like mass. (4) The vas deferens. This is the
excretory duct of the testicle. It can be felt as a thick tube, and is
placed towards the posterior border of the cord and to its inner side, where
it is enclosed in a special fold of the tunica vaginalis. It is exposed in
Plate XVII., since this fold has been slit open. The vas deferens runs
from the tail of the epididymis to the ejaculatory duct. At the vaginal
ring it separates from the other constituents of the cord, and passes
backwards, upwards, and inwards to the pelvic cavity. It runs over the
supero-lateral aspect of the bladder, and inclining towards the middle line
comes into relationship with the inner surface of the vesicula seminalis.
Behind the vesicula the tube becomes very much expanded, to form
what is known as the bulbous portion of the vas deferens. It terminates
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174 THE SURGICAL ANATOMY OF THE HORSE
under the prostate gland by uniting with the neck of the vesicula to
form the ejaculatory duct, which penetrates the wall of the urethra.
(5) Bundles of unstriped muscle, forming what is known as the internal
cremaster. (6) The tunica vaginalis propria.
The External Cremaster Muscle.—This arises from the iliac fascia, where
it blends with the origin of the internal oblique muscle. It runs down the
canal on the postero-external surface of the tunica vaginalis, to which it is
inserted where the latter is reflected on to the tail of the epididymis.
In the human subject the term cord is appropriate, since the structure is
rounded and cord-like. In the horse this is not so, for when the tunica
vaginalis is slit, it is more sheet-like. Its anterior end is thick and
rounded, and this contains the blood-vessels, nerves, and lymphatics.
These are points of importance to remember when performing the
operation of castration, or operating on a scirrhous cord. The cord
itself is supplied with blood by the artery to the cord, which is a
branch of the external iliac artery, but which sometimes comes off from
the posterior aorta.
The Vesiculce Seminaks.—There are two of these. Each is a small
pyriform sac, placed on the posterior part of the superior surface of the
bladder. In the stallion they are about six inches long and one to two
inches in breadth. They are usually much smaller in the gelding. The
anterior end, or fundus, is blind and rounded. Posteriorly, the vesicula
becomes constricted, forming a short duct. The anterior portion is
covered by peritoneum. The wall consists of fibrous, muscular, and
mucous coats, and the duct unites with the vas deferens, as already stated.
The Testicle and Epididymis.—The testicle is an ovoid gland, suspended
in the scrotum. It has a length of from four to five inches, a depth of two
and a half inches, and a breadth of one and a half inches. The two testicles
are frequently unequal in size, the left being usually the larger. Each
presents two surfaces, two borders, and two extremities. The surfaces,
extremities, and inferior border, are convex. The superior border is
almost straight, and this is where the spermatic cord is attached. The
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THE MALE GENITAL ORGANS
l75
epididymis is attached to this border, and slightly overlaps the external
surface of the gland. The average weight of a testicle is from ten to
eleven ounces. It is the gland which secretes the semen. The epididymis
is an irregular structure placed superiorly. Its anterior end is enlarged,
forming what is known as the head, caput, or globus major ; posteriorly,
there is a smaller enlargement known as the globus minor, or tail ;
whilst the narrow connecting portion is the body. The epididymis is
made up of the extremely convoluted excretory tube of the testicle.
Leaving the globus minor, this tube is continued as the vas deferens.
The greater part of the testicle is covered by the visceral portion of
the serous tunica vaginalis. Beneath this the gland substance is enclosed
within a dense white fibrous layer, known as the tunica albuginea. The
tunica vaginalis and a very thin tunica albuginea also spread over the
epididymis.
The testicle is supplied with blood by the spermatic artery, and the
blood is returned by veins which form the pampiniform plexus. Nerves
from the renal and posterior mesenteric sympathetic plexuses form a
spermatic plexus in the anterior rounded end of the cord, and from this
filaments are distributed to the gland. The interesting structure of the
gland itself does not call for description here.
OPERATIONS ON THE SCROTUM
Injuries to the scrotum are common in the dog, but owing to the '
protection afforded this region in the horse, they are comparatively rare in
this animal. Occasionally the integument is lacerated, and at times the
wound is so deep as to expose the testicle. The usual treatment for
wounds should be adopted, and when the testicle is exposed, it should be
cleansed, replaced, and the wound closed by sutures. In cases of
extensive laceration the sutures should be supported by applying a
suspensory bandage. In cases of serious injury to the gland itself,
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176 THE SURGICAL ANATOMY OF THE HORSE
frequently the best course to pursue is to remove it by castration. When
the gland is slightly contused, relief will be afforded by hot fomentations,
and by supporting the part by a suspensory bandage, or a special testicle
suspender, such as Fleming's.
HYDROCELE
This is the name given to an abnormal accumulation of fluid between
the layers of the tunica vaginalis. Occasionally the fluid is found outside
the vaginal sac. It may occur as an extension of ascites, or be due to
some external injury. As the fluid accumulates, the scrotum enlarges
inferiorly, and the swelling may attain the size of a man's head. The
testicle itself can generally be felt if the postero-inferior part of the swell-
ing be carefully palpated. The swelling is pear-shaped, is soft and
elastic, has a smooth surface, and fluctuates. There is usually, therefore,
little difficulty in distinguishing between it and a hernia. This may be
confirmed by rectal exploration. The quantity of fluid varies from a few
ounces to two or three quarts.
Several methods of treating the affection have been employed.
Various local applications have been utilized, but with unsatisfactory
results. There is little difficulty experienced in removing the fluid with
an aspirator or a fine trocar and canula. But the fluid usually reaccumu-
lates, and herein the greatest difficulty lies. Perhaps the best course is to
castrate the animal with clams in those cases where it is not necessary
to preserve the testicle. If hernia is also suspected, the operator should
expose the tunica vaginalis, and make a slit in it above the epididymis.
Through this slit the part can be explored with the finger. Should this
confirm the presence of a hernia, the animal should be castrated, the
covered method of operation being adopted. If it is essential to preserve
the testicle, good results sometimes follow the injection of tincture of
iodine after the withdrawal of the fluid.
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VARICOCELE AND SARCOCELE
177
VARICOCELE AND SARCOCELE
In old horses the veins of the spermatic cord are sometimes varicose.
In rare cases it is said that the arteries also are involved, and open into the
veins. Owing to the dilatation of the vessels, the anterior rounded portion
of the cord becomes greatly enlarged, and the swelling is elongated from
above to below. It will be readily understood from what we have said
that it will extend up the front of the cord. A careful palpation will
enable one to differentiate between this condition and a hernia, for the
pulsating vessels can usually be felt. Occasionally the testicle itself becomes
greatly enlarged, and we have the condition known as sarcocele. The
enlargement may be due to a variety of causes. Sometimes the gland is
the seat of a malignant growth, such as a carcinoma.
If the above conditions are complicated by an accumulation of fluid in
the scrotal sac, it is usually advisable to remove this first. The only
effective method of treatment, subsequently, is to castrate the animal—the
covered method being adopted whenever possible.
CASTRATION, OR EMASCULATION
This is an operation which is generally performed in this country with
the object of adding to the utility of the working animal. From what
has been said, it will be gathered that it is not infrequently demanded in
the treatment of some pathological or surgical condition.
It is not surprising that in an operation which has been performed for
centuries, and which is so general, there are many different methods.
It may be performed standing, or the animal may be placed on its
side or back. For the standing method it is claimed that the risks
attending casting are avoided. In some parts of the country casting the
animal is regarded as being so risky that clients demand the standing
operation. Statistics have demonstrated time and again that this risk has
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178 THE SURGICAL ANATOMY OF THE HORSE
been much exaggerated. There are distinct advantages associated with
having the animal cast. In the first place, the operator can see without
difficulty the whole of the operation area. He can control haemorrhage
much more effectively, and as a rule much less traction is placed upon
the cord. Preparation of the seat is also usually much more efficient. There
is less risk of injury to the operator himself. For an operator to subject
himself to any risk which can be avoided is certainly not surgery,
although it might be the means of making him appear smart to the
untutored.
The Standing Operation
A twitch should be applied, and the animal backed into a corner with
its right side against a wall. A restless animal may be blindfolded.
Other operators employ various other methods of restraint, but these are
not necessary, for the less the restraint the better does the animal appear
to stand. The parts having been cleansed and dried, the operator stands
with his back towards the horse's head, passes his left hand towards the
scrotum, which is grasped above the testicles in such manner that the
two spermatic cords are clutched between the middle fingers. The
scrotum is made tense by pressing the testicles downwards and backwards,
A castrating knife is then taken in the right hand, which is passed round
the left thigh and then forwards between the legs. The cutting edge is
now directed upwards, and a longitudinal incision made from before back-
wards, the entire length of the right testicle, the whole of the layers of
the scrotum being incised, and the gland exposed. The left gland is
exposed in a similar manner. The scrotal coverings are then pressed
upwards to expose the cords. The whole of each cord, with the
exception of the rounded anterior portion containing the vessels, is
severed with the knife. There are several methods of dealing with
the vascular portions of the cords. Probably the best method is to
crush through it with one of the different kinds of emasculators, or
castrators, of which the best known to the writer are the Reliance and
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CASTRATION, OR EMASCULATION
179
Huish-Blake. Others remove the testicles with the ecraseur, but this
instrument is not so convenient for this operation as the emasculator.
The vascular portions of both cords may be included together within the
chain of the ecraseur, and this can be done also with some emasculators.
Before applying the instrument, it will assist in checking haemorrhage if
the cords be twisted two or three times. The operation of crushing
should be performed slowly. After the testicle has been taken away with
the emasculator, it is advisable to allow the instrument to remain in
position for about one minute before opening the jaws. Some operators
apply wooden clams to the cords, and remove the testicles later.
The wound is washed with antiseptics, and the operation is complete.
Should serious haemorrhage occur later, the scrotal sac should be plugged.
The Recumbent Operation
It is advisable to anaesthetize the animal in the recumbent operation.
The animal may be cast with a rope or hobbles. The latter are the
more convenient for casting, but the rope method is the better for the
performance of the operation, since the hobbles approximate the feet and
restrict the operation area, whilst with the rope method a clear wide field
is presented, and the hind legs can be drawn well forward, with the hocks
out of the way of the operator. A long, thick, and fairly soft rope is
doubled, and its centre taken. Here a collar is formed by making a
figure-of-eight knot. This kind of knot will lie flat, and will not damage
the chest. The rope collar is then passed over the head, and the two free
ends of the rope slipped backwards between the two fore legs. They are
then separated; each is taken by an assistant and passed round the outer
side of the corresponding hind leg. The end is now carried forwards
between the hind legs and passed through the rope collar. A side-line is
passed around the body at the loins, and knotted loosely. Two or
three assistants now take hold of each of the free ends of the rope. The
operator slips the two loops down below the fetlocks of the hind limbs,
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180 THE SURGICAL ANATOMY OF THE HORSE
and gives the order to pull. When the animal goes down, the assistant
at the head presses his weight on the head to prevent the animal raising
it. A half-hitch or two is wound round the hind pastern, and similarly
around the corresponding fore pastern, which is brought backwards and
thus secured. The animal is then turned over, and the two opposite
limbs secured similarly, when the patient is turned on its back. The side-
line is now untied and its ends separated. Each end is then wound round
the cannon region of the corresponding hind limb. This serves the purpose
of keeping the limbs down, and prevents the animal arching its back.
The penis is withdrawn, washed thoroughly, or douched with tincture
of iodine, and rubbed over with some lubricant, such as vaseline or lard, as
is also the interior of the sheath. This will facilitate the protrusion of the
organ after the operation. For this purpose some use zinc ointment.
The whole of the perineal area is cleansed and dried. The part is then
thoroughly palpated, to ascertain whether both testicles are normal and that
there is no hernia. The scrotum covering one of the testicles is now made
tense by grasping between the thumb and maximus finger of the left hand,
as in Plate XVIII. The scrotum is next opened. Some do this with the
sharp edge of a hot firing iron ; others use the castrating knife. It can be
done very well with an ordinary scalpel. The opening should be made
longitudinally, parallel to, and quite clear of, the middle line, and should
pass through all the coverings, leaving the testicle exposed. The latter
will then usually slip out. The grip with the left hand is now released ;
the testicle is taken in the left hand, and with the right the coverings are
pressed downwards (in the position of the animal), leaving the cord
exposed. The posterior portion is slit with the knife, and a pair of clams
applied to the vascular portion. These are held with the left hand, the
testicle being allowed to lie sideways along the clam. With a dull red iron
the cord is now severed and the vessels seared. The cord is severed so
that half an inch or a little more projects above the clams. This will
allow the searing process to be continued until the vessels are completely
closed. The handles of the clam are now seized with the right hand,
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CASTRATION, OR EMASCULATION                  181
particular care being taken not to drag the cord at all; the left hand is
passed from before backwards beneath the clams in such manner that the
cord lies between the maximus and annul us fingers. These hold it gently
between them while the clams are opened. Some open and close the
clams two or three times before removing them. This has a tendency to
reopen the seared vessels. Held between the fingers in the manner
indicated, the seared end can be examined ; and if no blood escapes, and the
searing is considered satisfactory the cord may be released and allowed to
fall into the scrotum. If blood should ooze, there is no difficulty in
reapplying the clams and in continuing the searing process. After having
completed this part of the operation, precisely the same procedure is adopted
in dealing with the other testicle. Care must be taken, when opening the
scrotal sac, to keep clear of the median line. The part is now dusted well
over with dry dressing or smeared with antiseptic ointment, and the
operation is complete. The above is the " clam and iron " method. It
is that which is much the most generally adopted, and is still, perhaps,
for all purposes and under all conditions, the best. Many different kinds
of clams are used. Most have their advantages, and in considering these
much depends upon the operator. Wooden clams (boxwood) are light
and easily manipulated. One operator, whose arm readily tires, prefers to
use this type when operating on valuable animals, and in each case uses
a new clam. Obviously, wooden clams cannot so readily be rendered
aseptic as metal ones. The operation is sometimes performed with the
animal in the latericumbent position. In this case the upper hind limb is
drawn well forward and secured.
There are, as stated, other methods of operating. Possibly the most
surgical is that of ligaturing the blood-vessels. This method was adopted
before the advent of aseptic surgery, and it is not surprising, therefore,
that it met with little success. It was reintroduced and practised by
several operators some ten years ago, but, strange to say, is little practised
now. Fleming and others recommend it when castrating old horses.
The writer has frequently practised it when castrating donkeys from five
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182 THE SURGICAL ANATOMY OF THE HORSE
to eight years of age, for use in collieries. Recourse to this method was
taken owing to the great difficulty experienced in closing the vessels with
the iron. The lumen of the vessel in this animal is relatively broader
than in the horse. The animal is cast as usual, and the scrotum opened
with the knife. The anterior vascular part of the cord is dissected out,
and the remainder severed. A needle with a stout double sterilized thread
is passed through the rounded cord about an inch from the epididymis,
and the threads are then severed from the needle with the scissors,
leaving two threads with four free ends. The two ends of one thread are
carried forwards and then tied, enclosing half the cord. They are then
carried backwards round the whole cord and secured at the back. The
ends of the remaining thread are first carried backwards round the
posterior half, and then forwards round the whole cord. In this manner
the vessels are effectively ligatured, and there is no danger of the ligature
slipping off. The cord is severed just above the epididymis with the
knife, and the testicle removed. The parts are cleansed with antiseptics,
smeared over with antiseptic ointment, and the animal allowed to rise.
There has been very little swelling of the parts, and all the cases, without
exception, have recovered without any untoward incident.
One of the oldest methods is castration by torsion, and this method is
still commonly practised in the smaller animals. The method consists in
rupturing and simultaneously closing the spermatic vessels by twisting the
vascular portion of the cord. After opening the scrotum with the knife,
this is easily done with the fingers alone in such a small animal as the cat.
But in the larger animals much greater difficulty is experienced, and in
them much unnecessary damage is frequently inflicted on the upper parts
of the cord, and too much friction exerted upon it, during the process of
twisting. The walls of the vessels are much tougher, and are not easily
ruptured. To overcome this difficulty, several different kinds of forceps
have been invented. Some operators use only one pair to hold the cord
whilst the testicle is being twisted. Others employ two—one to hold the
cord, and the other fixed a little nearer the epididymis, and utilized
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CASTRATION, OR EMASCULATION                   183
to perform the twisting, the cord being severed between the two points
at which the instruments are applied. Should there be hemorrhage
afterwards, the vessels should be ligatured. The parts are dusted over with
dry dressing. This method, although by no means commonly practised
in this country in the horse, has been recommended as one which is
" comparatively painless, simple, and safe."
The Covered Operation
This method of operation has been referred to as being necessary in
treating abnormal conditions, such as inguinal and scrotal herniae, etc. It
consists in removing the testicles without opening into the serous
covering—the tunica vaginalis. It is a safe method, since there is,
obviously, less risk of septic peritonitis occurring as a sequel. The animal
is cast and the usual preparatory treatment employed. Much greater
care is required when making the incision in the wall of the scrotum.
The cutaneous incision should be slightly longer than in the ordinary
method, and it is advisable that the first incision should pass through
the skin only. A similar incision is next carried through the dartos, and
then through the cremasteric layer, with the fascia on either side. This
will expose the tunica vaginalis, and will be the necessary depth of the
incision. These layers should be worked downwards (the animal being
on its back), and the tunica vaginalis exposed as much as possible. If a
hernia is present, it should be reduced, and a convex clam applied, with
the convexity upwards. A clam of this kind can be applied higher up
and nearer the external inguinal ring. Special clams are supplied by
Arnolds for the purpose. The clam is tied as firmly as possible outside
the tunica vaginalis. Some operators remove the parts beneath the clam
at once, and allow the clam to remain in position for about three days or
even longer. Others allow the dependent structures to remain also until
the clam is removed. The end of the cord is now pressed upwards, the
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184 THE SURGICAL ANATOMY OF THE HORSE
lips of the scrotal opening are approximated, but not sutured, the parts
dusted over with dry dressing, and the operation is complete.
Scraping through the spermatic vessels with the knife, and crushing
through them with the ecraseur, are methods which have been utilized,
and the latter is sometimes employed now.
Complications and Seqjjel^e
Hemorrhage occurring at the time of the operation should be dealt
with at once. It may be necessary to reapply the clams and sear the
end of the cord again. Some dress the stump with haemostatics, or
compress the end for some time with a pair of long-jawed artery forceps,
and others are content to plug the scrotum with tow or cotton-wool.
Secondary haemorrhage occurring some time after the operation is more
serious. The animal should be immediately recast, and the parts
cleansed. The most effective method of dealing with a case of this
type is to ligature the cord in the manner described in castration by
ligation.
Prolapse of Omentum or Intestine.—There is always a liability to a
complication of this kind after castration in those cases where the
internal inguinal ring is large, and there is uneasiness and straining on the
part of the animal. Prolapse might occur even after the covered
operation, when the clams have been removed. Occasionally a large piece
of omentum or knuckle of intestine becomes extruded, and hangs down
for some distance from the scrotal opening. In other cases a small
knuckle of intestine may not extend downwards farther than the inguinal
canal, and may here become strangulated.
In the former cases attention is at once attracted, since the prolapsed
parts can be seen. In the latter, symptoms of strangulated inguinal
hernia are presented. Treatment follows the general principles adopted
in treating hernia. Much depends upon the condition of the prolapsed
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185
SCIRRHOUS CORD
part. If the case is seen early, and the part appears quite normal,
attempts should be made to return it. The animal is cast and
anaesthetized ; this will relax the parts and facilitate reduction, which is
attempted bv manipulation after the parts have been cleansed by gently
sponging with a weak but warm solution. A clam is then fixed outside
the tunica vaginalis to prevent a recurrence. If a large portion of omentum
has descended, and has become much altered, a little more should be
withdrawn, a ligature passed round the healthy portion, and the parts
below removed. The portion with the ligature is manipulated back into
the inguinal canal, and the clam applied outside the tunica vaginalis as
before. The most unfavourable cases, in which little if anything can be
done with hopes of success, are those in which the intestine has been
down some time, and unhealthy changes have occurred, when its surface
presents a blackish-brown appearance.
SCIRRHOUS CORD
This is another sequel of castration. After castration it is usual to have
considerable swelling of the parts, including the stump of the cord.
This is the ordinary acute inflammatory swelling, which as a rule
quickly subsides, and of which in about a fortnight there is no trace.
Occasionally the acute symptoms subside, and the swelling of the stump of
the cord diminishes; it does not entirely disappear, however, but begins
to increase again, and this time does so slowly, for the inflammatory
process is chronic. This is the condition commonly known as scirrhous
cord. The stump enlarges, and ultimately presents a tumour-like
appearance. The size of the enlargement varies considerably, as also does
its shape. At times it is more or less rounded, and confined to the end
of the stump. In other cases it is elongated, and extends up the cord
even beyond the internal inguinal ring. The weight varies from a few
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186 THE SURGICAL ANATOMY OF THE HORSE
ounces to over twenty pounds. The scrotal wound does not heal, and
from it small quantities of pus are discharged at intervals. Diagnosis as
a rule is easy. The swelling can generally be felt in the inguinal region,
and a probe will reveal the presence of even a small opening which
persists in the scrotum. Large swellings interfere with the action of the
animal, and there is an abnormal abduction of the limb on the side
affected. The cause is not definitely known. It has been associated
with several different micro-organisms, such as the Discomyces equi of
Rivolta, the micrococcus of Johne, staphylococci, and others. As M oiler
states, " it is clear that the disease is of an infectious nature, and may
possibly be caused by more than one organism." There are quite a
number of common occurrences during an ordinary castration which might
be regarded as predisposing causes of an affection of this kind. Some of
the methods of dealing with the cord and its coverings are so rough and
coarse, under the guise of being quick and smart, as to be unworthy of the
name of surgery. When it is considered for a moment what a highly
vascular structure is being dealt with, and the richness of its nerve-supply,
it is not surprising that complications of the type described are common.
It should be handled with care and delicacy. The unnecessary
" tu§Smg " which may be so frequently observed is to be condemned..
Even when the stump is taken between the fingers in order that the end
can be examined after the clams are removed, no more pressure should be
exerted than is necessary to suspend it. Why undue licence is taken in
this operation because it happens to be commonly practised is difficult
to comprehend. One has only to consider the structure of the part and
the important relationships of the cord to see that the operation is one
which demands delicate manipulatory and surgical skill.
It will be gathered that imperfect drainage would also predispose
to the formation of a scirrhous cord. The position is one which is
particularly favourable to the securing of proper drainage, and it is only
when the scrotal incision is too small, and closes too quickly, that a
complication of this kind arises.
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SCIRRHOUS CORD                                    187
Many different forms of treatment have been adopted, such as the
application of astringents or caustics, local injections, and internal
administration of iodide of potassium. Although the last-mentioned
is sometimes effective in reducing the size of the growth, and on this
account might be given in cases where the growth is very large, to
facilitate the subsequent performance of an operation, the only effective
method of treatment consists in excising the enlargement. A complete
examination of the patient should be made. The inguinal region is care-
fully palpated, and this, together with a rectal exploration, will enable
the operator to form some idea as to the size of the growth. When the
growth extends into the abdominal cavity, treatment by operation is
generally regarded as ineffective. Those which are the most easily
operated upon with success are the cases where the tumour is confined to
the end of the cord, and the adhesions between it and the surrounding
structures are not very firm.
The animal should be cast, placed under a general anaesthetic,
and turned on its back, the hind limb of the affected side, or both if
necessary, being drawn and fixed well forwards. The area is now
thoroughly cleansed, and by means of a probe the depth and direction of
the sinus is ascertained. Occasionally there are more than one. In some
cases the growth is very dependent, and does not extend far upwards.
An incision should be made in the skin, and in these cases separation
down to the tunica vaginalis can usually be effected with the fingers.
The chain of the ecraseur is then passed round the cord outside
the tunica vaginalis (i.e., as in the covered operation), and the cord is
severed gradually. These are simple cases. In cases where the growth
is large and is adherent to a considerable portion of skin, it is usual to
make an elliptical incision in the skin, the size of which depends upon
the growth, and the skin within this incision is removed with the
tumour. A stout tape is then passed through this elliptical portion of
skin in such manner as to obtain a firm hold, by means of a seton needle.
The ends of the tape are tied, leaving a loop, by means of which either
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188 THE SURGICAL ANATOMY OF THE HORSE
the operator himself or an assistant can control the growth during the
process of dissection. These growths as a rule are highly vascular, and
profuse haemorrhage occurs unless great care be taken in dissection. The
operator should have the cutting edge of the knife directed more towards
the skin and avoid cutting into the growth, excepting when this is absolutely
essential. Much unnecessary haemorrhage can be avoided in this way.
Having completed the separation between the growth and the skin,
the breaking down of the surrounding connective tissue becomes easier,
and can generally be done with the fingers. In some cases it is impossible
to pass the chain of the ecraseur around the cord, so far up the canal does
the growth extend. Practically the only course left to the operator in
such cases, unless the inguinal opening be enlarged, which is not
desirable, is to employ a strong aseptic ligature. There are several
contrivances which enable one to apply a ligature, the simplest, perhaps,
being that described by Fleming, which is " in the form of a small tube of
wood or metal, eight or ten inches in length, into which the double ligature
is passed, so as to make a loop at the end. This loop is pushed high up
over the tumour until the portion of healthy cord is reached, when it is
tightened to the necessary degree by pulling the ends of the cord at the
other extremity of the tube, where they are secured by tying them on a
small piece of wood placed across this extremity. Every second or third
day the tube may receive a twist or two, which will tighten the ligature,
and hasten the process of separation."
The wound should be subjected to the usual antiseptic treatment, and,
if necessary, should be packed with tow or cotton-wool, plentifully
sprinkled with dry dressing.
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THE DESCENT OF THE TESTICLES                  189
THE DESCENT OF THE TESTICLES
During the early stages of its development the testicle is placed in
relation to the inferior surface of the corresponding kidney close to the
roof of the abdominal cavity. As growth of the animal proceeds, the
organ leaves this position and passes down the inguinal canal to become
permanently accommodated in the scrotal sac. Whilst in the abdom ina
cavity the testicle hangs in a fold of peritoneum, known as the
mesochorium, which envelops anteriorly the vessels and nerves of the
testicle, and posteriorly the tail of the epididymis, together with a short
fibrous cord, which later forms the ligament of the epididymis. At the
posterior end of the mesochorium also is the gubernaculum testis, another
fibrous structure which extends from the posterior end of the epididymis
downwards and slightly backwards to the position where the vaginal
ring will later be formed. During the later stages of foetal development
a diverticulum of the peritoneum, the tunica vaginalis, or processus
vaginalis, passes downwards through the inguinal canal. It carries
with it a cremasteric layer, and a layer from the fascia transversalis,
and into the canal the gubernaculum testis also extends to become
blended inferiorly with the layer which later forms the dartos. Into this
pouch of peritoneum the testicle passes, carrying before it the visceral
layer of the tunica vaginalis, or mesochorium. The tail of the epididymis
enters first. Simultaneously the vas deferens descends the back of the
canal and the vas also carries with it a visceral serous layer.
The gubernaculum testis has been generally supposed to function as
a guide to the testicle in its descent from the sublumbar region to the
inguinal canal, and by progressive shortening of its inguinal portion to
exert traction on the gland and assist in its passage through the abdominal
wall. The matter remains, however, to a certain extent in obscurity.
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ioo THE SURGICAL ANATOMY OF THE HORSE
CRYPTORCHIDS
In many foals both testicles have completed their descent and are
present in the scrotum at birth ; but this is by no means general, and
the time at which one or both can be detected in the scrotal sac varies
considerably. In a process which is so complicated and in which there
are evidently so many conditions which operate, this variation is not
surprising, for it would appear that a very slight hitch in one of the
operating factors in the delicate mechanism could readily be the means
of delaying the descent and causing a retention of the organ in the
inguinal canal or even the abdominal cavity. Assuming that the develop-
ment of the remaining parts proceeded uniformly, it is fairly obvious that
owing to the " setting " of the structures and the progressive contraction
of the vaginal ring which normally occurs, a testicle delayed for an
abnormal length of time in its descent from the sublumbar region to the
vaginal ring would have greater difficulty in entering the latter, and the
tendency would be for it to be retained in the abdominal cavity. Retention
in the abdomen is thus, we find, the common permanent form, retention
in the canal being usually temporary. Occasionally the testicle itself is
diseased.
Most writers on the subject refer to the probability of the condition
being hereditary. Little doubt can be thrown on this probability in
many cases, since a peculiarity in structure and conformation might be
inherited which would have a marked effect on the descent of the
testicles. But that all cases are hereditary is open to grave doubt. To
an animal in which both testicles are not present in the scrotum, the
term cryptorchid (or commonly " rig ") is applied. Bilateral cryptorchids
are those in which both testicles are concealed, unilateral cryptorchids, or
monorchids, have one testicle in the scrotum.
Cryptorchidism is common in the horse, but it also occurs in other
domesticated animals and in the human subject.
Anorchids, in which the testicles are absent, are extremely rare.
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CASTRATION OF CRYPTORCHIDS
191
CASTRATION OF CRYPTORCHIDS
For the performance of this operation the animal should be cast and
anaesthetized. There are several different methods of tying and fixing
the animal. That described in detail for the ordinary operation of
castration will suffice, since the side-line, as applied, keeps the hind legs
well down and apart. The object must be to keep the hind legs well
separated. For this reason ordinary hobbles should not be utilized for
this operation. Farmer Miles adopted a very elaborate method of tying,
as also does his old pupil, Blakeway of Stourbridge. Although at first
sight a good deal in this way is done which might appear unnecessary,
one has only to observe the ease by which the operator enters the inguinal
canal and carries out the remainder of the operation to appreciate the
splendid field which this method provides. Donald's method also
provides a good field. It is described in the Journal of Comparative
Pathology,
vol. i.
If there is any difficulty experienced in keeping the legs apart, a
spreader may be used, that provided by Arnolds being useful and simple.
What is required is a position which will facilitate a ready access to the
inguinal canal.
The area is thoroughly cleansed and disinfected. An oblique incision
is made through the skin and subcutaneous fascia level with the external
abdominal ring, or slightly nearer the middle line and parallel to its long
axis. The incision should be from four to five inches long, and is best
made by puncturing the skin, then introducing a grooved director and
running the knife along this. This will avoid injury to the plexus of
large veins found at the external abdominal ring (Plate X.). These
veins are so numerous, and some of them are so large, that injury to them
leads to inconvenient haemorrhage, which in some cases is said to have
even proved fatal. Any haemorrhage should be arrested by means
of artery forceps or, if necessarv, ligatures, and the part dried with
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192 THE SURGICAL ANATOMY OF THE HORSE
pledgets of sterilized tow or cotton-wool. The hand is now the best
instrument, and the inguinal canal is reached best and safest by insinuating
the fingers between the structures, pressing aside the vessels, and breaking
down the connective tissue, which is here fairly abundant. The index
and maximus fingers can now be introduced into the inguinal canal,
and a search made for the testicle. Should it be found, the
remainder of the operation is little different from that of ordinary
castration. In some cases, although the testicle cannot be found in the
canal, the operator can feel a portion of the tunica vaginalis, and even a
portion of the epididymis. If gentle traction fails to bring the testicle
into touch, it becomes necessary to enter the abdominal cavity.
When the hand is in the canal, behind it is the reflected portion of the
tendon of the obliquus abdominis externus ; in front is the fleshy portion
of the obliquus abdominis internus, the soft muscular fibres of which can
be detected without difficulty. The internal abdominal ring is ill-defined,
for here is a quantity of loose connective tissue. Some gain entrance by
breaking this down. But although, if anything, easier to enter the
abdominal cavity in this manner, an abnormally large internal abdominal
ring remains which is patent, with therefore a predisposition to the
subsequent formation of an inguinal hernia. For this reason the method
recommended by Bang is to be preferred.
Instead of breaking down this fascia, he insinuated the fingers between
the fibres of the internal abdominal muscle, thus making a new and some-
what circular opening slightly nearer the middle line than the internal
abdominal ring. An opening made in this manner has the advantage
in that it quickly closes after the operation has been completed. It is
not necessary to rupture the muscle to any appreciable extent. The
bundles of fibres are separated with little difficulty in most cases. In
others more force is necessary, owing to a tendency to fix the abdominal
muscles. On passing the index and maximus fingers through the aper-
ture thus made, a careful search should be made for the testicle. It not
infrequently happens that the tips of the fingers come into contact with
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CASTRATION OF CRYPTORCHIDS
193
it immediately they are introduced into the abdominal cavity. At other
times great difficulty is experienced in finding the missing organ, and it
may be necessary to pass the whole hand into the abdominal cavity.
When doing this, the hand should be contracted as much as possible, since
the testicle, when found, is usually abnormally small and can be withdrawn
through such an opening without much difficulty. As soon as the hand
enters, loops of intestine may be felt. These must be dealt with carefully,
and a ball of faeces must not be mistaken for the missing gland. They
are not difficult to identify, since balls of faeces are usually numerous and
have a relatively harder consistency to the touch. At times the testicle
appears to float into the hand ; at others, a systematic search has to be
made for it. An endeavour should be made to locate the vas deferens.
The feel of this has not inaptly been compared by Hobday to that of a
piece of " soaked string." When a cord of this kind is found, it should
be traced to the testicle, the posterior end of which the vas deferens
leaves. Running to the other end of the organ is the spermatic artery,
the pulsation of which can be felt. The fairly characteristic feel of the
body will confirm identification, and if compressed with the hand, the
animal will flinch. If satisfied with the identity, the organ should be
withdrawn through the inguinal canal and removed with the ecraseur.
The wound is then carefully cleansed and swabbed out. If the testicle
is found in the canal and the abdominal cavity has not been entered,
the after-treatment is the same as that adopted in ordinary castration.
If it is necessary to enter the abdomen, the cutaneous wound must be
closed by means of fine, closely-set sutures. The part is then dusted
over with dry dressing, and the operation is now complete.
This operation has also been performed in the flank. In the case of
a monorchid, the animal is cast on the side opposite to that of the missing
testicle. An incision is made similar to that in laparo-enterotomy, and
which has already been described in detail. Through the opening thus
made, the hand is introduced and directed backwards towards the internal
abdominal ring, the position of which will be evident on reference to the
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i94 THE SURGICAL ANATOMY OF THE HORSE
plate representing a transverse section taken through the lumbar region.
Working from the ring upwards, a search is made for the testicle, which,
when found, is removed with the ecraseur. The wound is closed by
suturing the different layers separately in the manner already described,
and the area is painted over with iodoform and collodion.
The animal is now placed in a loose box with clean bedding, and
given a little gentle exercise daily. On the third day the sutures should
be removed, and free drainage provided by separating the lips of the
wound a little. The wound should be dressed with antiseptics until all
discharge ceases.
Abnormal conditions of the testicles in cryptorchids are common.
The occasional presence of dentigerous cysts containing partially developed
molar teeth is well known, as is also the fact that the testicle and its
coverings are sometimes the seat of the strongylus armatus. Cystic
testicles may attain a very large size, in which case the cyst should be
punctured with the finger-nail and its liquid contents allowed to escape
into the peritoneal cavity before the testicle is removed. Degive and
Cadeac, in cases in which the testicle is too big to be removed, pull the
cord into the inguinal canal, remove a portion of it, and leave the testicle
free in the abdominal cavity.
THE PREPUCE AND PENIS
The Prepuce.—In the horse the prepuce is peculiar as compared with
the prepuce of the human subject. It is commonly called the sheath, and
when the penis is non-erect, it consists of an outer cutaneous involuted
tube, which has two layers, the outer continuous with the surrounding
integument, and the inner, which is continuous anteriorly with the outer,
and which is reflected backwards. There is another and smaller tube
placed within that just described. Its outer layer is continuous posteriorly
with the inner layer of the outer tube, and its inner layer posteriorly is
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THE PREPUCE AND PENIS                          195
reflected on to the penis. This inner tube is strictly the homologue of
the human prepuce. The inner layer of the sheath, or outer tube, is
usually darkly pigmented, devoid of visible hairs, and has numerous
preputial glands, which secrete a sebaceous material of a peculiar odour.
This forms with the shed epithelium the smegma preputii. The inner
layer of the sheath is coarser and more wrinkled than the surface of the
prepuce proper. There are no sebaceous glands on the inner layer of the
latter. The outer layer of the sheath is continued backwards into the
scrotal integument, and presents a median raphe. Forwards it extends to
just behind the umbilicus, where inferiorly and laterally it is reflected
backwards to become continued as the inner layer. Superiorly it is
continued forwards into the skin of the abdomen. There is here,
therefore, an opening bounded laterally and inferiorly by the thick edge
where the sheath becomes reflected backwards. This is known as the
preputial orifice, or ostium praeputiale. Nerves are distributed to the
cutaneous portion of the sheath, which come from the inguinal nerves.
These descend through the inguinal canal from the second and third
lumbar nerves. The blood supply comes from the subcutaneous
abdominal artery, which in turn is a branch of the external pudic artery.
Like the nerves, this artery comes through the inguinal canal. The
nerves and artery, which, it may be observed, are not within the spermatic
cord, may be seen in Plate X.
INJURIES TO THE SHEATH—INFLAMMATION
(BALANITIS)
In the horse the prepuce is frequently damaged, and inflammation of
it, technically called balanitis, is common.
Geldings occasionally fail to extend the penis during micturition, and
irritation of the prepuce is set up owing to urine being discharged into it.
The irritation leads to contraction of the outer walls of the sheath,
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196 THE SURGICAL ANATOMY OF THE HORSE
making it still more difficult to protrude the penis, and in some cases there
is complete inability to do this, and we have the condition known as
phimosis. The smegma accumulates in greater quantities, so great in
some cases as to exert pressure on the urethra, and make urination
difficult. The condition is progressive, and unless the case receives
proper attention, serious complications, such as rupture of the bladder,
lead to the death of the animal. M oiler states that the condition in many
cases is due to a habit of rubbing the sheath and penis with irritating
substances such as pepper, the irritant being often so powerful as to cause
necrosis of the parts. The object of applying these is to attempt to
relieve colic or difficulty in micturition.
Treatment consists in cleansing the parts thoroughly. A thorough
washing out with warm water and soap is necessary to remove the
accumulated smegma. A free exit for the urine must be provided.
Astringent solutions should be applied when symptoms of acute
inflammation are present, and much relief is afforded and recovery is
hastened in those cases where there is considerable swelling of the sheath by
applying a suspensory bandage. Any raw areas should be covered with
zinc ointment. A free application of vaseline to the sheath and
surrounding parts is a common method of treatment. In marked
stenosis of the preputial orifice it may be necessary to enlarge it surgically
by slitting it with the knife inferiorly, the edges being prevented from re-
uniting, and held apart by suturing them to the surrounding skin. This
is a simple operation, which in some animals 'can be performed without
other restraint than the application of a twitch.
TUMOURS ON THE SHEATH
These are frequently seen in the horse. The kind which are
commonly encountered are fibromata, or warty growths ; but tumours of
a more malignant kind sometimes develop, such, for instance, as
carcinomata. As might be expected from the normal structure of the
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THE PENIS
197
part, the growths are not infrequently pigmented with melanin. In many
cases the growths do no harm, and are simply an eyesore. In others,
again, serious complications arise as a result of their development, such,
for instance, as stenosis of the sheath with phimosis or paraphimosis.
They may also cause difficulty in micturition through mechanical
pressure on the walls of the urethra. Treatment depends upon the kind
of growth. A fibroma, which is pedunculated, may simply be removed
with the scissors ; then the application of stick caustic or the actual
cautery will effectively check haemorrhage, and tend also to prevent a
recurrence. Removal with the elastic ligature is a method commonly
practised, whilst others treat with powerful caustics, such as nitric or
sulphuric acid, particularly if the tumours have broad diffused bases.
THE PENIS
This is the male organ of copulation. It extends from the ischial
arch forwards in the middle line to the umbilical region on the inferior
aspect of the abdominal wall, where it ends in a free expansion known
as the glans. Its posterior portion is fixed and extends from the ischial
tuberosities, to which it is attached by what are known as the crura to
the scrotum. When the organ is non-erect, the anterior free and pro-
trusible portion is lodged in the prepuce. When in a condition of
erection, this part projects in front of the scrotum, and the prepuce
proper becomes obliterated.
A cross section will show that the organ in outline is somewhat
elliptical, with its long axis disposed vertically. It is made up of the
corpus cavernosum and the corpus spongiosum. The former is some-
times described in two parallel portions, one arising from each inferior
ischiatic spine. These unite to form a single mass, which makes up the
greater part of the penis. The superior surface of this mass is flattened,
and along it the dorsal nerves and vessels of the penis run. Inferiorly it
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198 THE SURGICAL ANATOMY OF THE HORSE
is grooved for the corpus spongiosum. Its sides are rounded. The
anterior end of the corpus spongiosum terminates in the glans. The
corpus cavernosum is made up of erectile tissue enveloped in a tough
white fibrous coat known as the tunica albuginea, from which a number
of trabecular pass inwards. There is sometimes described an incomplete
median septum—the septum pectiniformi.
The trabecular are made up of white fibrous tissue with unstriped
muscle fibres, and they join in such manner as to form a framework for
the body, which has been aptly compared to a sponge, dividing it up
into a large number of freely intercommunicating spaces. The spaces
are really capillaries much enlarged. They are lined by flat endothelial
cells, and blood from them is drained by the veins.
The corpus spongiosum is a much smaller body and is placed
inferiorly. It is also made up of erectile tissue, and throughout its
length the extra-pelvic portion of the urethra runs. The erectile tissue
forms a kind of sheath around the urethra. Posteriorly the corpus
spongiosum in many animals is enlarged, forming the bulb which is
placed near the ischial arch. This bulb is very small in the horse.
Anteriorly it becomes much enlarged, forming the already-mentioned
glans penis. When the penis is erected, the glans is circumscribed by a
well-defined ridge known as the corona glandis, behind which is a groove
—the cervix. The anterior end of the urethra projects freely in a fossa
on the front of the glans. This projecting portion is the urethral tube,
and it has a length of about half an inch. The suburethral notch is an
interruption in the corona glandis below the urethral tube, and above the
tube is the opening of a cavity known as the urethral sinus. In structure
the corpus spongiosum is similar to the corpus cavernosum. It has a
fibrous covering with trabeculas. These latter are finer than in the
corpus cavernosum. The spaces are small, with the exception of those
in the glans, which are very large. The lumen of the portion of the
urethra within the corpus spongiosum is not uniform. It presents a
dilatation near the ischial arch, and another just behind its slightly-
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THE PENIS                                           199
constricted anterior extremity. This latter dilatation corresponds to the
human fossa navicularis.
The Blood-Vessels.—On each side of the upper surface there are two
arteries, known respectively as the anterior and posterior dorsals. The
former is one of the divisions of the external pudic artery which divides
after leaving, or just within, the inguinal canal. This division has a length
of only a few inches, when it splits into two portions, one of which
courses forwards in a flexuous manner, when the organ is non-erect,
along the dorsum of the protrusible portion of the penis. The other
passes backwards along the fixed portion to anastomose with the posterior
dorsal artery. The latter is a branch of the artery to the corpus
cavernosum, which in turn comes from the obturator artery, and it runs
forwards to anastomose with the anterior dorsal artery in the manner
described.
Branches from the dorsal arteries pass to the corpus spongiosum and
corpus cavernosum, and their terminal branches are distributed to the
glans.
The artery to the corpus cavernosum is detached from the obturator
artery after the latter passes out through the obturator foramen. Running
backwards along the inferior aspect of the ischium, it gives off the posterior
dorsal artery and then passes into the crus penis.
The veins of the penis form a rich plexus on the dorsum and sides,
and this plexus is drained by the external pudic and obturator veins.
From the crura the blood passes into the internal pudic veins.
There are two dorsal nerves of the penis which are disposed in a
flexuous manner to admit of the erection of the organ without the nerves
undergoing undue stretching. They are the continuations of the pudic
nerves, which curve round the ischial arch to reach the dorsum.
Numerous branches are distributed to the body of the penis, and the
terminal filaments pass to the glans.
Besides the accelerator urinas muscle, which has been described with
the urethra, there are two muscles in connection with the penis:
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2oo THE SURGICAL ANATOMY OF THE HORSE
The Erector Penis or Ischio-Cavernosus Muscle.—There are two of these.
Each arises from the corresponding tuber ischii and great sacro-sciatic
ligament, and is inserted into the crus penis. It is placed between the
crus and the semimembranosus muscle, in which there is a groove for its
accommodation. Its action is to pull the root of the penis upwards, and
by compressing it against the pelvis, to exert pressure upon the dorsal
veins, thus assisting in erection. Its nerve-supply is derived from the
pudic nerve, and the obturator artery contributes its blood-supply.
The Retractor Penis.—This arises from the inferior aspect of the centra
of the first two or three coccygeal vertebras in the form of two bands of
unstriped muscle fibres, which run downwards one on either side the
rectum. Below the anus the two bands meet, where the fibres commingle
and form a kind of supporting sling for the posterior end of the rectum
and the anus. The muscle runs between the two layers of the accelerator
urinas muscle, and then longitudinally along the inferior surface of the
penis beneath the last-named muscle. Behind the glans it is inserted in
bundles into the tunica albuginea, to reach which the bundles pierce the
accelerator urinae from without inwards. As its name implies, the muscle
pulls the penis back into the sheath after protrusion, and the sling-like
portion draws the anus upwards and supports it during defalcation.
PHIMOSIS AND PARAPHIMOSIS
Phimosis is the technical term applied to the condition in which the
ostium prssputiale is abnormally small, and in consequence the animal is
unable to expose the glans and protrude the penis. The conditions under
which it occurs in the horse have already been dealt with when con-
sidering the affections of the sheath.
Paraphimosis is the converse condition, in which the glans cannot be
withdrawn into the sheath. It is common in the dog, but is much more
rare in the horse, since the outer fold of the sheath presents relatively a
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PHIMOSIS AND PARAPHIMOSIS
20I
much larger orifice, and in consequence less difficulty is opposed to the
withdrawal of the penis. The condition is attributed to a number of
different causes ; although frequently attributed to paralysis of the retractor
muscles, it is doubtful, as Moller states, if this ever occurs simply. The
condition has been reported as a sequel to thrombosis of the vessels. It
is most commonly due to injury to the penis itself. As stated, the outer
fold of the sheath, even when much swollen, is so disposed as to be rarely
the cause of paraphimosis. Swelling of the inner fold, such, for instance,
as occurs after castration, may, however, cause it (hence the necessity for
exposing the penis and lubricating it and the sheath as stated, before
castration). Occasionally the penis cannot be retracted even when the
acute inflammatory symptoms have disappeared. In these cases inability
is frequently attributed to paralysis of the retractor penis. In some cases
of purpura hemorrhagica, paraphimosis occurs as a sequel, and its occur-
rence under these conditions is difficult to explain. The protruded penis
is particularly exposed to risk of injury. It is commonly damaged. In
some cases it is struck by the hind feet during progression. The whole
of the area should undergo a most careful examination. Where the
condition is due to an abnormality of the sheath, the line of treatment
has already been indicated. In some cases of persistent swelling relief is
afforded by superficial scarification and then applying astringents with a
pad of tow or cotton-wool supported by a suspensory bandage. The
penis itself should be thoroughly cleansed, then washed over with
astringent solutions, and suspended in a bandage with plenty of packing.
WOUNDS AND TUMOURS ON THE PENIS
When there are wounds on the penis, such as are sometimes accident-
ally inflicted with the whip or during coition, the wound or swelling
frequently affects the urethra, which becomes compressed so that there
is difficulty in micturition. Lacerated wounds of the penis are usually
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202 THE SURGICAL ANATOMY OF THE HORSE
quite amenable to treatment. As the acute symptoms of inflammation
subside, the bending of the organ which generally occurs in such cases
usually disappears. The usual treatment for wounds should be adopted,
the part being cleansed and dressed with antiseptics. A suspensory
bandage will assist recovery, and will also be found a useful help in the
application of dressings.
The penis is also the seat of tumours and tumour-like growths, which
in many cases are extremely troublesome. They are of great inconveni-
ence to the animal, interfere with the protrusion and retraction of the
penis, and consequently with micturition. At times they emit a most
offensive odour. They may be benign warty growths which are readily
snipped off with the knife or scissors. Occasionally cancerous growths
of a most malignant type develop, and resist all methods of treatment
other than amputation of the affected part of the organ. Papillomata
are not uncommon on the glans penis.
Regarding treatment, practically the same methods in the case of many
of these growths apply as in similar growths on the sheath. Malignant
growths, as stated, frequently necessitate amputation of portion of the penis
to effect a cure and render the animal workable.
AMPUTATION OF THE PENIS
In addition to cancerous growths other conditions which necessitate
the performance of this operation are—Inflammation of the organ of some
standing, in which changes have occurred, such as necrosis; and para-
phimosis, when all attempts at returning the organ have failed. In
performing this operation the operator should always bear in mind the fact
that the organ has a rich nerve-supply, and, in consequence, is extremely
sensitive; it is very vascular, with the result that unless great care be
taken, profuse haemorrhage will be the result; and, lastly, but perhaps the
point of greatest importance, the great tendency to stricture which the
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AMPUTATION OF THE PENIS
203
urethra possesses after any surgical interference with it has taken place
which has not been in strict accordance with the definitely laid out
methods of procedure—a complication which we have already pointed
out is frequently associated with the most disastrous results.
There are several methods of performing the operation. Some
operators have been bold enough, when circumstances have demanded it,
to cut through the organ without ligaturing the vessels, and rely upon
compression of the stump for a considerable time to prevent haemorrhage.
In this connection Hunting's well-known case quoted by Moller is
worthy of notice. A pony's penis was simply cut through, the stump
compressed for half an hour, and little haemorrhage resulted. Obviously
this would be a dangerous procedure to adopt generally, as those who
have had experience in the amputation of the organ and the removal of
growths from it will appreciate.
A method which has been, and still is, frequently adopted, is ligation.
Although this has a great advantage over all other methods in that it is the
one in which haemorrhage is most effectively checked, it has some disadvan-
tages, and in adopting it there are some points to which particular attention
must be given. To keep the lumen of the urethra patent, some operators
introduce into it a metal tube. Whilst performing its function in this
respect it cannot be urged that this is an effective protection against
undue compression of the urethra, such as will lead ultimately to the
formation of a stricture. The best method of dealing with the urethra
when ligation is adopted is to dissect it out and exclude it altogether
from the ligature. After the ligature is applied it is tightened daily, and
in about a week the amputation is complete. This is the greatest
objection to ligation. It is obviously a long and painful process, and the
present tendency towards enforcing the general administration of anaes-
thetics may render the method illegal.
Another method is to sever the organ by means of a sharp-edged
actual cautery. The animal is cast, and placed under a general anaesthetic.
The urethra is dissected out, and about an inch of it left to project beyond
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2o4 THE SURGICAL ANATOMY OF THE HORSE
the free end of the stump. Two ligatures are then applied and the
section is made between them, the posterior ligature being utilized to
control the stump after section. In adopting this method the operator
should remember the position of the dorsal vessels, and should sear them
carefully. The ecraseur is commonly used to cut through the organ.
The animal is cast, the parts are thoroughly cleansed, and the animal is
anaesthetized. The urethra is dissected out and cut through, so that a
portion from an inch to an inch and a half in length will project from the
stump. The chain of the instrument is then passed around the rest of
the organ. At first the instrument is easily worked, because the corpus
cavernosum is easily compressed and crushed through ; but the tunica
albuginea is so tough that it presents great resistance, and the crushing
process must be proceeded with carefully, otherwise the chain has a
tendency to snap. When this happens, a ligature is placed around the
organ at the constriction, and amputation completed with the knife.
From what was said at the outset, it will be gathered that the
subsequent treatment of the end of the urethra is a matter of the greatest
importance ; and upon it the ultimate success of the operation will depend,
for stenosis of it must be effectively prevented. Operators differ as to the
best method of achieving this desired result. Some claim that it is best
simply to cut through the tube, leaving a freely protruding portion of
about an inch in length, and to subject this to as little interference as
possible.
Another method is to divide the projecting portion of the urethra
into four flaps by two incisions into it at right angles to each other, and
these are fixed back to the edge of the stump by means of fine sutures.
Moller and Dollar adopt some very important modifications of a
method which has been frequently practised on the human subject.
They map out a complete triangle on the inferior aspect of the organ,
expose this portion of the urethra, slit it longitudinally, and cut it
transversely. The flaps are sutured to the edge of skin on either side.
Just beyond the base of the triangle—i.e., on the side of the glans
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AMPUTATION OF THE PENIS                       205
penis—a rubber cord is wound tightly four or five times around the penis
and tied firmly, and about an inch nearer the glans than this ligature
the penis is divided transversely with the knife. Two ligatures are
used—the one to control the stump, and the one just described. The
latter is allowed to remain in position, with the result that necrosis of the
end of the stump occurs. Separation takes place at the ligature, and this
and the necrosed tissue come away in from six to ten days, leaving the
end of the stump deeply notched inferiorly, and the end of the urethra
reflected on to the anterior face of the stump and sutured to the skin
as before.
W. L. Williams uses two ligatures in this manner, and when cutting
through the corpus cavernosum does so in a direction upwards and
forwards. This renders easier the suturing process. He sutures in a
manner which effectively prevents hemorrhage. A straight needle with
silk suture is passed through the edge of the wall of the urethra at the sides
of the triangle before referred to. The needle passes through the corpus
spongiosum and the tunica albuginea of the corpus cavernosum. It is
then brought out, and passed over the surface of the latter, and not
through it. Superiorly the needle is again passed through the tunica
albuginea and the skin, with the vessels between them. When the ends
of these sutures are tied, the edges of the tunica albuginea are brought
together over the erectile tissue, and the edges of the urethra and skin are
approximated in such manner as to compress the dorsal vessels, and thus
hemorrhage from these and the erectile tissue is effectively prevented.
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206 THE SURGICAL ANATOMY OF THE HORSE
THE FEMALE GENITAL ORGANS
THE OVARIES
These are the reproductive organs in which the ova are produced.
They are situated one on either side, superiorly, in the sublumbar portion
of the abdominal cavity, each being placed a short distance (from two
to three inches) behind the corresponding kidney. The size varies in
different subjects. They are usually referred to as being about equal to
an average hen's egg. But one ovary is frequently larger than the other,
and both are larger in the young animal. The average weight is from
two and a half to three ounces. The shape has been not inaptly
compared to that of a short haricot bean, and two surfaces, two edges,
and two extremities, may be described. When the other viscera are
removed, the surfaces are disposed laterally—outer and inner—but in the
ordinary position the organs are pressed upwards, and the surfaces
become superior and inferior. The surfaces are convex and smooth.
They are covered by the peritoneum. The upper border, when the
ovary hangs freely, is convex, and is attached to the uterine broad
ligament. The vessels and nerves enter the organ at this border. The
inferior or free border, which is the shorter, is curved, with the concavity
directed downwards. It presents a notch which leads into the depression
known as the ovulation fossa. The anterior end is rounded, and related
to the anterior or fimbriated extremity of the Fallopian tube. The
posterior end is also rounded, and to it is attached the ligament of the
ovary which connects it with the horn of the uterus.
The ovaries are in contact with the roof of the abdominal cavity. A
point of considerable surgical importance is that their distance from the
entrance to the vulva is on an average about twenty inches.
In structure the ovary is made up of a fibrous framework of firm tissue,
greyish in colour, throughout which rounded, cyst-like bodies, known as
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THE OVARIES
207
the Graafian follicles, are scattered. The Graafian follicles, or ovisacs,
contain the ova. When fully developed the follicles become placed
superficially, and may even form projections on the surface of the ovary.
In the mare the follicles burst during oestrum, and set the ova free at the
ovulation fossa.*
The ovarian artery is a vessel of considerable calibre. It passes in a
flexuous manner to the attached border of the ovary, between the layers of
the anterior portion of the broad ligament, which is sometimes called the
mesovarium. The veins form a plexus in a manner somewhat similar to
that of the spermatic cord. The nerve-supply is derived from the renal
and aortic sympathetic plexuses, and the nerve filaments follow the
course taken by the artery and its branches.
In old mares the amount of fibrous tissue is proportionately much
greater, and in this cysts are frequently present, some of which attain a
considerable size.
The parovarium, which corresponds to the epididymis in the male, is
found between the ovary and the Fallopian tube. It is placed in the broad
ligament, and is made up of a number of short twisted tubules, which
open into a tube running longitudinally. The latter is said to represent
the canal of Gaertner in the cow.
The Fallopian Tubes, or Oviducts.—These convey the ova from the
ovaries to the uterus. Each has a length of about twelve inches, and is
arranged in a very flexuous manner in a fold of peritoneum which is derived
from the outer layer of the broad ligament, and is called the mesosalpinx.
The ovarian end of the tube opens on the surface of an expanded part,
the edge of which is split into a number of short irregular processes
called the fimbria?. This end is thus called the fimbriated extremity, and
the aperture is the ostium abdominale, which communicates with the
cavity of the peritoneum. Some of the fimbria? are attached to the ovary
in front of the ovulation fossa. When the ova are extruded from the
* For a more detailed account of the microscopical structure a textbook on histology should
be consulted.
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208 THE SURGICAL ANATOMY OF THE HORSE
ovulation fossa, they fall into the ostium abdominale. The uterine end
of the tube opens into the horn of the uterus by a small aperture called
the ostium uterinum.
The tube has an external serous coat; then comes a muscular coat
made up of outer longitudinal and inner circular fibres. The internal or
mucous coat is thrown into a number of longitudinal folds. The
epithelium consists of a single layer of columnar cells. They are
ciliated, and the movements of the cilia direct a current towards the
uterus.
The utero-ovarian artery supplies the tube with blood, and its nerve-
supply is the same as that of the ovary.
On some of the fimbria? hydatid cysts are frequently found. These
are known as the hydatids of Morgagni, and they are usually pedun-
culated.
REMOVAL OF THE OVARIES
The term oophorectomy is applied to the operation of removing the
healthy ovaries, but if the organs are diseased the operation is termed
ovariotomy. " Spaying " is commonly applied to both. As is well known,
unless required for breeding purposes, female pigs are generally spayed
when suckers. The operation is commonly practised also on the bitch
and cat. In human surgery, ovariotomy is by no means uncommon,
whilst during recent years the operation has been frequently performed
on mares which are presumed to be troublesome owing to disease of the
ovaries, and with the object of making them more workable. The
operation has been performed for centuries. Fleming states that mares,
cows, sows, ewes, and camels, were castrated in the days of Aristotle.
According to Bartholin, it was apparently performed in Denmark in the
middle of the seventeenth century, the seat of operation being the flank. In
1850 Charlier removed the ovaries through the vagina, and this is certainly
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REMOVAL OF THE OVARIES
209
the best method of reaching the organs to-day. The ovaries can be reached
without difficulty through the rectum, and the rectal method of perform-
ing the operation has been practised. But there is obviously much less
risk of septic infection attached to operating through the vagina.
Originally the operation as practised by Charlier was a somewhat
complex procedure. He designed a special instrument for dilating the
walls of the vagina, knives with concealed blades for making the incision
through the vaginal wall, long pairs of torsion forceps peculiarly adapted
for the removal of the ovary, and a special thimble to enable the operator
to obtain a firmer grip of the ligament of the ovary. Later, Colin, who
devoted much attention to the subject, dispensed with the dilator and with
the thimble. The method of removing the ovary by torsion was still
retained, and instead of the thimble Colin used a special spring forceps
with broad flat blades, a circular ring for the thumb being attached to
one, and an elliptical ring for two fingers to the other. His torsion
forceps was a slight modification of the one used by Charlier. Delafond
dispensed with the torsion forceps, and substituted the ecraseur, the use of
which was subsequently popularized by Cadiot. Thus the operation has
been modified, one difficulty after another proving to be more imaginary
than real, until to-day it is comparatively a very simple matter. The
operation was generally performed with the animal in the standing
position and secured in stocks, and this position is still recommended by
some as being that in which the ovaries can be most easily found.
Whilst this is so, on the grounds of humanity a general anaesthetic
should be employed, and the trend of modern legislation is such that the
standing method might be entirely prohibited.
The animal should be cast on her side, the right side being usually
selected, although the particular side is not a matter of much consequence.
The external genitals and the surrounding area should be cleansed, and
the vaginal cavity filled with a weak and warm solution of some
antiseptic, such as chinosol. This is allowed to remain in for some
minutes, and then swabbed out until the wall of the cavity is compara-
2 d
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210 THE SURGICAL ANATOMY OF THE HORSE
tively dry. The interior of the chamber may now be examined by the
operator introducing his hand, which has been disinfected and lubricated.
The hand passes at first through a portion of the passage which appears
to be somewhat constricted, but on arriving at the main cavity of the
vagina the wall is loose and flaccid, and for a time seems to fold around
the hand. This flaccidity soon disappears, and the wall becomes tightly
distended, a condition which has been referred to as the " ballooning " of
the vagina. This condition affords a splendid opportunity for the examina-
tion of the interior of the cavity, the os uteri, the position in which the
incision is to be made, etc. The student should make his examination
now, as it is the best condition in which he can obtain a knowledge of
the geography of his surroundings. The incision through the vaginal
wall must be made above the os uteri in the middle line. The animal is
now placed under a general anaesthetic. A knife with a concealed blade
(there are several different patterns) is carried into the vagina, the walls of
which are now more flaccid. The os uteri is felt, and the blade is
exposed, its cutting edge being directed towards the wall above the os in
a manner which would be vertical if the mare were standing. The blade
is pressed downwards and forwards with a sharp, bold thrust, in order that
it may pass also through the peritoneal layer ; otherwise, when the hand
is introduced through the incision, this latter layer is pressed forwards, and
adds to the difficulty of proceeding with the operation.
If the incision has been properly made, communication is established
between the vaginal cavity and the recto-vaginal pouch of the peritoneum.
This step is the most important in the whole operation. Above the
incision is the rectum, and in close proximity are the posterior aorta and
iliac arteries. Obviously, these structures are to be avoided. Hence
pressure on the knife must be directed mainly forwards and slightly
downwards. The latter enables the structures mentioned to be avoided.
On the other hand, too much downward pressure might lead to laceration
of the wall of the uterus. Having made the incision, the knife should be
withdrawn from the vagina. The hand is now reintroduced, and a finger
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REMOVAL OF THE OVARIES
21 I
passed through the opening made. The opening is then enlarged by
insinuating another finger, and still a third, until the whole hand can be
passed through. With the knuckles directed towards the spine, the
palmar aspect of the fingers lies against the body of the uterus, and tracing
this forwards the angle of division of the cornua can be felt. The ovary
is found by following one of the horns. Its consistency varies. It may
be soft and flabby, or indurated. In old mares normal ovaries, as stated,
have a much greater proportion of fibrous stroma. In size they may be
no larger than a walnut, whilst, on the other hand, cystic ovaries are
sometimes found which attain the size of a cocoanut. The " feel"
of the organ can only be acquired by practice. It is a useful exercise to
make the incision on a freshly-killed subject, pass the hand up the
passage and examine the parts in the manner described. In the dissecting-
room much useful information can be obtained, even after the abdomen
has been opened, by making the incision, and by one student passing his
hand up. Meanwhile, the others, by watching, note the course taken by
the hand in the abdomen, and the positions of the surrounding structures.
A ball of fasces must not be mistaken for the ovary. It is easy to
distinguish between them, if it be remembered that usually several balls
will be present arranged in a row, and that by compressing one it can be
moved in the bowel. (To avoid this possible complication, the animal is
frequently denied solid food for several hours before the operation.)
Having found the ovary, it is taken in the palm of the hand and
grasped firmly. If it is loosely suspended and the ligaments are much
relaxed, as in some cases, it might be possible to bring it into the vaginal
cavity through the incised opening in the vaginal wall. If this can be done,
the rest of the operation is rendered much easier. If not, the long ecraseur
is taken in the other hand, the chain being only sufficiently released to
make a loop large enough to pass round the ovary ; and the instrument
is then passed along the passage close to the arm, up to the hand which
grasps the ovary. With the fingers of this hand the ovary is manipulated
through the loop of the chain, and a careful palpation made to decide
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212 THE SURGICAL ANATOMY OF THE HORSE
that no other structure, such as a loop of intestine, is included. It is
sometimes helpful to decide this if the ovary is first twisted around a little
to make the " stalk" better defined. The operator now holds the
instrument, and an assistant is instructed to turn the handle gradually. Care
must be taken that a portion of the vaginal mucous membrane does not get
wedged in the groove of the ecraseur. To avoid this, the operator should
pass his left hand up the vagina along the instrument. It is, however,
surprising how the presence of any additional structure becomes apparent
to an experienced assistant when working the ecraseur. The operator must
not release his grasp of the ovary, so that when section is complete the organ
can be withdrawn ; otherwise there is a possibility of its falling free into
the abdominal cavity. It will be gathered, from the anatomy of the part,
that the position of the ovary will be subject to some considerable degree
of variation, depending upon the relaxation of the ligaments. Occasion-
ally the fingers come into contact with it immediately they are introduced
through the incision in the vagina. Again, it will be understood that it
will prevent crowding of the intestines towards the area if the hinder
parts be raised to a higher level for the performance of the operation.
When both ovaries have been removed, the vagina should be cleansed by
swabbing with pledgets of tow or cotton-wool saturated with a weak
solution of some antiseptic. Solutions which are also irritant are contra-
indicated, since they only lead to subsequent straining, with possibly
displacement of a portion of intestine into the vagina as a complication.
It is unnecessary to suture the incised wound. Cadiot claims that it " is
spontaneously closed in twenty-four hours after the operation, and is
completely cicatrized in ten days."
When once the hand has been introduced into the abdominal cavity,
much fear has been attached, in the past, to withdrawing it until the
operation is completed. For this reason, some operators do not even
withdraw the knife after making the incision, but, after concealing the
blade, allow it simply to fall into the vagina. For the same reason, also,
a large number of different instruments have been invented and used.
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THE UTERUS
213
This fear is altogether unjustified. With what is now ordinary surgical
care (the animal, of course, being under an anaesthetic), the hand may
be withdrawn and reintroduced almost with impunity. Macqueen has
shown that there is no need for such dread of the peritoneal cavity of
the horse. When performing ovariotomy on the mare, the writer has
allowed all the members of a division of six or eight students to explore
the " ballooned " vagina and examine the seat of incision, to examine the
incision after it- has been made, and those students whose arms have not
been very short andv thick, to pass their hands into the peritoneal cavity
and ascertain the position of the ovaries; before proceeding with the
operation, and this without any ill-effects.
Very large cystic ovaries are sometimes punctured, and the contents
allowed to escape into the peritoneal cavity, or their contents may be
evacuated by aspiration.
THE UTERUS, VAGINA AND VULVA
The Uterus is the hollow organ with muscular walls which is com-
monly called the womb. It is placed mainly in the abdominal cavity, but
posteriorly it extends for a short distance into the cavity of the pelvis. It
is suspended by means of the broad ligaments, which were described when
dealing with the peritoneum. In the mare the organ is bifid anteriorly,
forming what are known as the two horns, or cornua. The whole of
each cornu is placed in the abdominal cavity, and its length is about ten
inches. In shape it is cylindrical, and its position varies. When freely
suspended, its upper border is concave, and its lower convex, but not
infrequently it is forced up to the roof of the abdominal cavity by the
intestines. Anteriorly the horn is pointed, and here is the ostium
uterinum. Its calibre gradually increases as we pass backwards to where
the two horns converge and join the body. The cornua are related
to the intestines. The body is placed partly in the pelvic cavity and
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2i4 THE SURGICAL ANATOMY OF THE HORSE
partly in the abdomen. It is slightly compressed from above to below, so
that its upper and lower surfaces are somewhat flattened, its edges
rounded, and in cross-section its outline approaches the elliptical. It has
a breadth of about four inches, and a length of six to seven inches. On
examining the exterior of the organ in situ, it appears to pass insensibly
into that of the vagina, and there is no line of demarcation between them.
This is evident on referring to the Plates illustrating ovariotomy.
Superiorly the body is related to the small colon and the rectum,
inferiorly to the intestines in front and to the bladder. The anterior
wide portion" is called the fundus. Posteriorly it becomes constricted,
forming the cervix, and part of this projects into the cavity of the
vagina.
When the animal is non-pregnant, the mucous lining is thrown into
folds, and the cavity is almost obliterated owing to this and the contracted
state of the walls. The interior communicates with the lumen of the
vagina by the cervical canal, but ordinarily this is closed by mucus.
Where the canal opens into the main cavity of the uterus we have the os
uteri internum, where it opens into the vagina the os uteri externum.
The latter, as stated, is usually closed, but in some cases the tip of the
finger can be inserted into it.
The wall of the uterus has an external serous coat continuous with the
broad ligaments, and a middle muscular coat consisting of an outer layer
of longitudinal and an inner layer of circular fibres, the latter layer being
much the thicker. It is extremely thick where it forms the sphincter of
the cervix. The internal is the mucous layer, the epithelium of which is
columnar. It is of a dark reddish colour, but is paler near the cervix. In
it there are numerous tubular glands.
The blood-supply comes from the uterine artery and the uterine
branch of the ovarian artery, which run in the broad ligaments. The
internal pudic artery also contributes to its supply. Its nerve-supply
is derived from branches which come from the uterine and pelvic
sympathetic plexuses.
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THE. VAGINA
2J5
The Vagina is the tubular passage extending backwards horizontally
from the uterus to the vulva. It has a length of from six to eight
inches, but the diameter of its lumen is subject to a considerable amount
of variation, as will be gathered from what has been said regarding
" ballooning" of the vagina. Ordinarily the diameter is about four
inches. Superiorly it is related to the rectum, inferiorly to the bladder
and urethra, and laterally to the pelvic walls. The peritoneum passes
from the rectum on to the vagina, forming the recto-genital pouch,
which covers only a small portion—about two inches—of the anterior
end of the vagina. Inferiorly the peritoneum is reflected from the vagina
on to the bladder, forming the vesico-genital pouch, and on this surface
rather less than two inches of the vagina has a peritoneal covering; thus
we find that much the greater portion of the vagina lies outside the limits
of the peritoneal sac. This portion is connected with the surrounding
structures by a quantity of loose connective tissue, in which there are
numerous veins, and frequently a considerable quantity of fat. The wall
of the vagina, where there is no peritoneal covering, consists of a muscular
coat made up of a thin external layer of longitudinal fibres and an inner
and thicker circular layer with numerous elastic fibres. The mucous coat
carries stratified epithelium. It has no glands, but is extremely elastic.
From the amount of elastic tissue present in the wall, it is not surprising
that it is capable of such a high degree of distensibility. Owing to the
falling in of the walls, as already described, the lumen under ordinary
conditions is almost obliterated; this is particularly so when fecal matter
collects in the ampulla of the rectum, when the lumen is simply repre-
sented by a slit-like aperture disposed transversely. In the mature animal
there is no line of demarcation between the interior of the vagina and
the vulva.
The vaginal branches of the internal pudic arteries supply it with
blood, and its nerve-supply comes from the pelvic sympathetic plexus.
The Vulva is the passage connecting the vagina with the exterior,
where it opens just below the anus. Superiorly it is related to the rectum,
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216 THE SURGICAL ANATOMY OF THE HORSE
to which it is attached by loose connective tissue; inferiorly it lies on the
posterior part of the floor of the pelvis, whilst its sides are in apposition
to the retractor ani muscles. Unstriped muscle fibres, forming what is
referred to as the anterior constrictor muscle of the vulva, cover it
inferiorly and laterally, and they pass upwards on to the sides of the
rectum. Two labia, one on either side, bound the external opening.
They meet above and below, forming the commissures, so that the
opening, which is slit-like, is disposed vertically. The superior com-
missure is very acute; the border of the inferior is arc-like, and within it
the clitoris lies. The skin covering the labia is thin, darkly pigmented,
and destitute of hairs. Beneath the skin lies the posterior constrictor
muscle of the vulva, consisting of fibres disposed after the manner of a
kind of sphincter around the entrance to the vulva. Some of its fibres
are inserted into the skin below the inferior commissure, and others into
the base of the clitoris. Superiorly the fibres mix with those of the
sphincter ani muscle. The contraction of the inferior fibres after mic-
turition exposes the clitoris. The mucous membrane lining the vulva
is of a rosy tint, and contains numerous follicles, which secrete mucus.
At the anterior end of the floor of the vulva is the meatus urinarius, or
opening of the urethra ; this is guarded by a valve-like fold of the mucous
membrane. By being continued upwards on either side in the young
animal, this forms what Sisson regards as the hymen.
The homologue of the corpus spongiosum is placed beneath the
posterior constrictor muscle, and between it and the mucous membrane.
It is called the vestibular bulb, and is composed of right and left halves,
which are joined inferiorly. It has the structure of erectile tissue.
The clitoris is another erectile body—the homologue of the male
penis minus the urethra and corpus spongiosum. Inferiorly it has a
bifid attachment to the ischial arch. The body projects upwards and
backwards for about two inches, and is made up of right and left parallel
portions, resembling miniature corpora cavernosa of the penis. There is
a rudimentary glans and a small cap-like structure analogous to the
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EXAMINATION OF THE FEMALE GENITAL TRACT 217
prepuce. The term vulva is sometimes restricted to the external orifice
and the structures which surround it, the remainder of the passage being
known as the vestibule.
EXAMINATION OF THE FEMALE GENITAL TRACT
The labia can be easily examined. If the lips are taken one between
the thumb and index-finger of each hand, they can be separated to such
an extent that their inner surfaces and the posterior portion of the vulvar
passage can be examined with the naked eye. It is frequently of im-
portance to make such an examination, for it commonly happens that one
of the lips of the vulva is considerably swollen, the swelling extending
around the inferior commissure as a result of a small laceration of the
inner or mucous surface, which is not visible unless the labia be separated.
By forcibly separating the labia with the four fingers of each hand, the
anterior portion of the vulva (or vestibule) with a little of the vagina may
be seen in a proper light. But farther than this naked-eye examination
cannot be carried out unaided. There are, however, a number of specula,
some of which also act as dilators, which enable one to ascertain the
condition of the wall of the vagina. Polansky's speculum is perhaps the
best for this purpose; but the hand can without difficulty be passed up
the passage, and is still one of the most useful aids to diagnosis. By this
means lacerations of the vaginal wall and tumours and other growths in
the vagina can be detected, and the condition of the os uteri ascertained.
In some cases, when the os is sufficiently dilated, the interior of the
uterus can be examined in this manner. Prolapse of the uterus into the
vaginal passage can, of course, be felt without difficulty, whilst it has
already been described (see Vesical Calculi) how the fingers can be intro-
duced into the bladder. The student should not fail to make himself
proficient in the conduct of such an examination.
2 e
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2i8 THE SURGICAL ANATOMY OF THE HORSE
INJURIES TO THE VULVA, VAGINA, AND UTERUS
Injuries to the interior of the vulva, vagina, and uterus, are not
uncommon. Laceration of the walls of the passage is a common sequel
to unskilful delivery during parturition. The wall of the vagina is not
infrequently damaged by instruments during the performance of ovari-
otomy—such, for instance, as when the mucous membrane gets caught in
the groove of the ecraseur and becomes entangled in the chain. Cases in
which the vaginal wall has been ruptured during coition have also been
recorded. In rare cases the wall of the vulva is damaged during the
careless introduction of the catheter. The most serious are those in which
the anterior portion of the wall of the vagina is perforated. This is
what usually happens when the rupture is inflicted by the penis of the
stallion during coition. This portion is clothed by peritoneum, so that
communication is established with the peritoneal cavity. Wounds in the
posterior part of the vagina are not subject to this complication, because
this portion is simply surrounded by connective tissue. Treatment should
follow general principles, the passage being kept clean, and disinfected
by washing out with weak antiseptic solutions which are also slightly
astringent. A lacerated wound in the posterior part of the passage can
sometimes be sutured. Wounds of the lips of the vulva require frequent
dressing to keep them clean, and the tail should be fixed and tied aside.
A ten per cent, solution of chloride of zinc is a very effective dressing for
wounds in this region. A fistula leading into the passage is treated on
similar lines to those indicated in treating fistula of the rectum.
INVERSION OR PROLAPSE OF THE UTERUS
Prolapse of the uterus only occurs when the organ is turned inside
out, so that inversion is probably the more correct term. It will be
obvious that the cervical canal must be dilated, otherwise inversion cannot
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INVERSION OR PROLAPSE OF THE UTERUS 219
take place, so that the condition occurs as a rule as a complication of
parturition. In some cases, during the process of inversion, the front of
the uterus becomes wedged in the cervical canal, and should it be also
strangulated most serious results follow. In addition to the dilatation of
the cervical canal, another factor which contributes to the occurrence
of inversion during the period of parturition is the relaxation of the
uterine ligaments, which allows much greater freedom of movement of
the organ. Retention of the afterbirth would then be a contributory
cause, because this would keep the cervical canal patent. Further,
manipulatory interference in removing the membranes might stimulate
violent contractions of the wall of the uterus and lead to inversion.
When the organ is completely inverted, there is little difficulty in
diagnosis. In some cases it hangs down as far as the hocks. In other
cases, when inversion is incomplete, the organ simply bulges into the
vagina, and is not visible from the exterior. Diagnosis in these cases
requires a careful examination and palpation of the part. The hand can
generally be insinuated between the protrusion and vaginal wall, and the
edge of the dilated os uteri felt. In complete inversion the protruded
organ gradually increases in size, owing to the interference with circulation
leading to an engorgement of the capillaries. Another factor which con-
tributes to its increase is produced by the violent efforts on the part of the
animal to expel it.*
If the surface of the organ is not altered or damaged, reposition should
be attempted without delay. The protrusion should be cleansed thoroughly
with lukewarm weak solutions of some antiseptic, and then covered with
a clean cloth to protect it from injury.
If the case be regarded as a difficult one, the mare should be placed
under a general anaesthetic, for, although the recumbent position of the
animal is not so favourable as the standing position so far as it affects
the operator's power of manipulation, this advantage is outweighed by the
* For a detailed account of the causation, symptomatology, and sequelae, a text-book on obstetrics
should be consulted.
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22o THE SURGICAL ANATOMY OF THE HORSE
greater degree of quietude of the animal and the absence of straining, the
latter being usually a great obstacle to successful reposition. The hinder
parts of the animal are raised to a higher level than the fore parts by
packing battens of straw, or sacks filled with some soft material, beneath
them. The larger of the two cornua is then taken and reduced, the
remaining cornu being subjected to the same process; the closed fist
is next applied to the broadest part of the body, and pressed forwards
in the longitudinal direction of the passage. The organ is thus
forced forwards and slightly upwards. The pressure must be applied
steadily and progressively, in order that the uterus may be gradually
returned.
When the protrusion is of immense size, the operator should com-
mence by manipulating those parts next the vulva back into the passage.
The weight of the organ is sustained by assistants, whilst the operator
utilizes both hands for this purpose placed flatwise, one on either side the
vulva. Having reduced the size of the protrusion in this manner, the
remainder may be replaced with the fist by the method described above.
Having returned the organ into the abdominal cavity, the hand should
now be passed up the vulva and vagina into the interior of the uterus, and
the latter should be carefully examined to ascertain that no portion—such,
for instance, as the extremity of one of the cornua—remains invaginated.
The hand in the interior of the organ is of assistance in spreading it out,
and in causing it thus to take up its normal position. Keeping the hand
in the organ until the walls show a tendency to contract also prevents
a recurrence of inversion.
There are many different methods of reducing the size of the organ to
facilitate reposition. Coculet enclosed it in dry linen in such manner as
enabled him to tighten the covering whenever necessary. To the linen
tepid water was continuously applied, and at minute intervals the cloth
was tightened. This ingenious method of applying gradual and con-
tinuous pressure is claimed to bring about a marked reduction in about
twenty minutes. Washing the organ with astringent solutions is another
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INVERSION OR PROLAPSE OF THE UTERUS 221
method. Some operators inject adrenalin for this purpose, and others
apply pressure by means of fairly tight bandages.
When the inversion is only partial, and the organ is not visible
externally, reposition by means of the fist is comparatively simple.
After reduction there are many devices for preventing a recurrence,
such as the application of trusses, the insertion of sutures across the vulva,
vulval clams, binders around the loins, the internal administration of
sedatives and anodynes, and the introduction of pessaries into the
vagina.
        'v
Davis of Enfield, in February, 1912, had a case of eversion of the
womb in a mare which occurred a little more than half an hour after
foaling. She was found " rolling about with the uterus extruded . . .
sweating, greatly excited, and in much pain, throwing herself down
(banging the womb on the bed as she did so), rolling over, and straining.
Taking advantage of the mare getting up, a twitch was put on, and the
near fore leg held up by an assistant, while two others supported the womb
on a stable rubber, raising it as high as they could. After compressing
the viscus in another stable rubber, to get rid of as much of the oedema as
possible, and having washed it with antiseptic, I commenced by returning
the parts next the vulva, and finally, with my fist in the fundus, got the
organ replaced, smoothed away all kinks, and put on a West's clamp.
The mare never showed a bad symptom. She was in season on the ninth
day, and was put to the horse, and is in foal." [Veterinary Record,
August 17, 1912.) He did not use chloroform, because he considered it
easier to replace the uterus with the animal standing, and, since the mare
stood fairly well with the twitch on, he thought it best to make no delay.
The course he took in this case was obviously justified by the result.
AMPUTATION OF THE UTERUS
This remains the only course to be taken when all attempts at reposition
have failed, and when the tissues of the displaced organ have been much
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222 THE SURGICAL ANATOMY OF THE HORSE
damaged, and such pathological changes, for instance, as gangrenous
areas have occurred, which render reposition dangerous to the life of the
animal.
The operation, however, should not be attempted until the surgeon
has completely satisfied himself as to its real necessity. Although
amongst the domesticated animals recovery is common in the cow and
bitch, the operation has been performed with a fairly good percentage of
successes in the mare.
Lanzillotti-Buonsanti reported six successful results out of eight cases.
As it is a painful operation, the animal should be cast and chloroformed.
The uterus is then carefully palpated, to ascertain that no portion of the
bowel or bladder is included in the inverted organ. If there is any doubt
on this point, an exploratory incision should be made. Should any such
complication be found, the portion of bowel should be returned to the
abdomen before amputation is commenced.
There are several methods of amputation which have been practised.
Simple ligation has been frequently adopted, and elastic ligatures are
commonly used. Whatever method is selected, care must be taken to
place the ligature so that, when placed back in position, sloughing will
occur along a line beyond the meatus urinarius. This is obviously a
point of the greatest importance. The ligature will also be affixed so
that it will not slip, otherwise there is a danger of exposing the peritoneal
cavity. The ecraseur has also been used to remove the uterus. Its use
in this connection is risky, owing to communication being established
with the peritoneal cavity, and the danger of septic infection. Probably
the best and safest method is to adopt the same process in ligation as that
described in detail when ligaturing the spermatic cord in castration.
After applying the ligatures in this fashion, the uterus is removed by
severing with the knife about three inches behind the ligature. The
neck of the uterus, or portion of vagina which remains, is now replaced
and pushed as far as possible in the genital canal. Frequent dressing of
the stump with antiseptics is all that is now necessary, and the ligature
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INVERSION OF THE VAGINA
223
with the tissue behind it will slough away in about a week, and the
passage at the line of application of the ligature is effectively closed, so
that there is here now a blind extremity.
INVERSION OF THE VAGINA
In some cases this condition is simply an extension of inversion of the
uterus. In such cases the latter projects outwards to such an extent that
the vagina is dragged after it, and the walls of the vagina are exposed
also. Such are the most serious cases of inversion, and the treatment
follows the lines already indicated in the preceding condition. When the
wall of the vagina only is inverted, the affection is much less serious. In
some cases it occurs during pregnancy, when the tendency is for it to
disappear after parturition. In other cases it is a sequel to parturition or
abortion. It will be understood that inversion of the vagina must
be preceded by a backward displacement of the uterus, with relaxation of
its ligaments, for otherwise the fixation of the uterus will effectively
prevent it. The ligaments become stretched in this manner, and the
uterus is easily displaced backwards in old mares which have borne
several foals. It is much more common, however, in cows. It will be
remembered that the posterior portion of the vagina is attached to the
surrounding structures by a quantity of loose connective tissue. In
complete inversion this is extensively lacerated. The swelling is more or
less rounded, and towards its centre the os uteri may frequently be felt.
On its inferior surface a longitudinal groove runs to the urinary meatus,
whilst on either side, at the neck of the swelling, the continuity of its
mucous covering with the mucous lining of the vulva can be determined.
The swelling must be examined carefully in this manner to avoid error in
diagnosis. If the case be seen early, the surface has a rosy red tint.
Later it becomes dry, and may show excoriations by being caught by
some projection, or by being damaged when the animal lies down.
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224 THE SURGICAL ANATOMY OF THE HORSE
Injuries to the surface may set up intense inflammation. Occasionally in
mares there is such severe straining that the vaginal wall is ruptured, and
through the rent the bladder or a portion of the bowel, or both, project,
leading in most cases to death of the animal.
Incomplete inversion has a tendency to reduce itself spontaneously, and
this is assisted if the animal be placed in a stall with the hind feet raised
above the level of the fore. When inversion is complete, the contents of
the bladder should first be removed. The exposed organ is then washed
and cleansed, and wounds on its surface dressed, and, if necessary, sutured.
Pressure is now applied against the swelling with the palm of the hand.
Should the animal strain, pressure must be relaxed, and reapplied when
straining has ceased. When it is returned to the level of the entrance to
the vulva, the closed fist is pressed against the centre and forced forwards,
the vagina before it, up the genital passage. The fist is placed against
the os uteri, and this is pushed as far forwards as possible, to obliterate
any folds in the vaginal wall. When reposition is complete, the wall of
the vagina is carefully palpated, to ascertain that there is no folding of the
mucous membrane, and that the latter presents an even surface. The
methods of preventing a recurrence are similar to those adopted in
inversion of the uterus.
Hewetson's case, quoted by M oiler and Dollar, is interesting. In a
young Clydesdale mare " the vagina had several times appeared prominent
previous to the actual accident. Reduction could not be effected owing
to struggling, so the parts were bathed three times a day with disin-
fectant or astringent solutions, and on the third day they returned
spontaneously. A fortnight later the prolapse again occurred. The
former treatment failing, the vaginal wall was scarified. Improvement
was slow, and the mare was turned out during the day. Three weeks
later the wound was healed, and the vagina could be replaced. West's
prolapse clamps were applied, and left in position for a month. Recovery
appeared complete."
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VAGINAL AND VULVAL CYSTS AND TUMOURS 225
VAGINAL AND VULVAL CYSTS AND TUMOURS
Both benign and malignant tumours are sometimes found in con-
nection with the wall of the vagina. Carcinomata, sarcomata, and
fibromata, have been reported, some of which have attained quite a
considerable size. Cysts are most common in the anterior portion of the
vulva—otherwise the vestibule. They are usually due to obstruction of
the ducts of the follicles described here. In some cases neither tumours
nor cysts cause much inconvenience. In others they attain such a
considerable size and are so placed as to interfere with micturition, when
they lead to straining, which sometimes results in prolapse. When the
cysts are placed near the vulva, they may be seen, and present a bladder-like
appearance. When farther forwards their presence can be ascertained by
manual exploration. To the touch they are soft and elastic. In some
cases there is a discharge of purulent blood-tinged liquid.
Occasionally there is formed in the vaginal wall a kind of hasmatoma,
forming a large ill-defined swelling. Tumours which are pedunculated
may be removed with the ecraseur or by ligation. When the bases are
broad and diffused, they may be removed similarly. But this leaves a
large wound which requires attention. If placed well back, the edges
may be sutured; otherwise astringent antiseptics should be utilized as
dressings.
Pressure with the hand will sometimes succeed in discharging the
contents of a cyst. In other cases they should be punctured. Some
operators remove them with a snare. Hasmatomata are treated by
scarification, dressing the area subsequently with cold solutions of anti-
septics.
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226 THE SURGICAL ANATOMY OF THE HORSE
OCCLUSION OF THE VAGINA OR VULVA
Partial occlusion of the vulval or vaginal passage may be either
congenital or acquired. In the latter cases the occlusion is generally the
result of wounds of the mucous membrane, leading to adhesions between
the opposite surfaces. Moller reports a case of a filly " which exhibited
occlusion of the vulva from its upper angle as far almost as the clitoris,
where an opening the size of a goose quill remained, from which urine
was discharged in a thin stream. The adhesion was divided ; but, as it
recurred several times, it was found necessary to pass the hand into the
vagina daily and dilate the vulva. Under this treatment perfect recovery
occurred."
Adhesions formed between the walls of the vagina present greater
difficulty. In recent cases it is sometimes possible to break them down with
the fingers. In others careful dissection is necessary. A vaginal dilator must
be utilized, and the walls behind the adhesion kept as widely apart as
is possible (without placing undue tension upon them, otherwise rupture
might occur). This will facilitate the dissection. A dilator well
lubricated with antiseptic ointment should then be passed up the passage
frequently, to prevent a recurrence of the condition.
According to Moller, the vagina is sometimes occluded in the mare
owing to a persistent hymen, when a " muco-sanguineous fluid " collects in
front of the hymen. The os uteri cannot be felt in these cases. The
condition is not difficult to treat, since the obstruction is easy to perforate.
THE MAMMARY GLANDS
These are the glands which secrete the milk. In the mare there are
two, and they are placed in close apposition, one on either side the median
line in the inguinal region. Each gland in shape resembles a laterally
compressed cone, the base directed upwards and the inner surface flattened.
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THE MAMMARY GLANDS
227
The base is concave, and related to the wall of the abdomen. Between
the wall and the gland there is a quantity of areolar tissue with a quantity
of fat. In this tissue a large number of veins are found, together with the
superficial inguinal or supramammary lymphatic glands. At the apex of
the gland is the teat—a laterally compressed nipple-like process, with a
length of from one to two inches, and the extremity of which is
perforated by two or three small orifices, which are the openings of the
milk ducts.
The glands are covered by a thin layer of pigmented skin, which is
for the most part devoid of hair, and which contains numerous sebaceous
and sweat glands. Two layers of fascia cover the gland, with the exception
of the teats.
The deep fascia has a peculiar arrangement. Between the two
glands it forms two sheets, which are attached to the abdominal tunic
above. They come into apposition in the median plane, and each forms
a kind of suspensory ligament for the corresponding gland. There is an
appreciable quantity of loose areolar tissue between the sheets, and it is
possible to dissect between the laminae, so that with care one gland can be
removed without interfering in any way with the other. This is a
point of considerable surgical importance. Enclosing the gland tissue is
a firm capsule with much elastic tissue. This capsule detaches inwardly
a number of trabeculas, which split the gland up into a number of lobules.
The glandular tissue is greyish-red in colour, and in it are the secretory
tubules, which open into ducts. From each lobule a duct passes, and
opens into a cavity at the base of the teat, known as the galactophorous
or lactiferous sinus, from which the milk can be drawn to the summit of
the teat through two or three lactiferous ducts. The sinus and lactiferous
ducts are lined by mucous membrane. In the ducts this is covered by
squamous epithelium, and is surrounded by unstriped muscle fibres
arranged circularly after the manner of a sphincter.
The gland is supplied with blood by the subcutaneous abdominal and
mammary arteries, which are branches of the external pudic artery. The
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228 THE SURGICAL ANATOMY OF THE HORSE
main nutrient vessel enters the posterior part of the base of the gland, and
must be sought and ligatured when the gland is extirpated. The veins
form a plexus at the base, which is drained mostly by the external pudic
vein. The gland is richly supplied with lymphatics, which pass to
the supramammary gland. The nerve-supply comes from the inguinal
nerves and the posterior mesenteric sympathetic plexus.
The amount of parenchyma, or gland tissue, varies considerably. It
is greatest during the later part of pregnancy and during the period
of lactation, when the gland becomes much enlarged. After the
lactation period is over the gland tissue gradually diminishes again.
INJURIES TO THE MAMMARY GLAND
In the mare the mammary gland and its teat are relatively small, and
this, together with the position, is particularly favourable to its protection
against injury. Consequently we find that injuries to the gland are very
much rarer than, say, in the cow or bitch.
Occasionally the surface of the gland is lacerated, when it should be
remembered that the treatment of wounds of the gland should follow the
general lines of treatment elsewhere. Large wounds should be rendered
aseptic and closed by sutures. The wound should then be sealed by
painting over it with iodoform and collodion. In some cases of deep-
seated wounds the milk is tinged with blood, indicating that the milk
ducts are involved in the injury. In these cases antiseptic solutions
should also be injected up the teat. Occasionally the gland is bruised by
being " butted " by the foal, when it becomes swollen and painful to the
touch. . Relief can frequently be afforded by hot fomentations, followed
by the application of some antiseptic emollient to the surface of the
gland. An abscess in the gland should be treated similarly to an abscess
elsewhere.
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EXTIRPATION OF THE MAMMARY GLAND 229
EXTIRPATION OF THE MAMMARY GLAND
Occasionally the mammary gland is so injured or diseased that
excision of a portion, or removal of the whole gland, is the only advisable
course of treatment. It is sometimes the seat of malignant growths.
It is said to be affected with carcinoniata. Botryomycosis of the udder
has also been observed.
Whether the whole or portion of the mass shall be removed depends
upon the extent of the diseased condition. Most frequently to remove
one of the glands—i.e., half the mass—will suffice.
The mare is cast, chloroformed, and placed on her back. Assuming
that it is the left gland which is to be removed, a longitudinal incision is
made about three inches to the left of the middle line. Both ends of this
incision are connected by a curved incision which passes around the outer
side of the teat, so that the latter is towards the middle of an elongated
portion of skin within the two incisions which is to be removed with the
gland. Through this skin a stout piece of tape is passed, the ends of
which are tied, leaving a loop by means of which the gland can be
controlled. Dissection should now proceed along the line of the first
incision towards the middle line. Having arrived at the septum between
the two glands, the knife should pass between the two layers, as already
indicated when describing the gland. Proceed now to reflect the skin
outwards from the curved incision to the base of the gland, care being
taken to keep the knife close to the skin. The base of the gland has now
to be dealt with, and this requires the greatest care. The posterior
portion of the gland should be drawn towards the operator, and a
search made at the hinder part of the base for the main nutrient artery,
which, it will be remembered, penetrates the gland here. When found
this should be ligatured, and dissection through the areolar tissue
connecting the gland with the abdominal wall proceeded with. Other
vessels should be seized and closed by compression with artery forceps, or,
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230 THE SURGICAL ANATOMY OF THE HORSE
if necessary, ligatured. Having thus removed the gland, the area should
be thoroughly washed out, and plugged with tow or cotton-wool saturated
with some antiseptic solution, or dusted over with dry dressing. One or
two sutures are inserted into the flaps of skin, to bring them together and
hold the plug in position. The plug can be removed after a day or two
by cutting the sutures, and the cavity is allowed to heal from the bottom
in the usual manner, being occasionally dusted over with dry dressing.
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CHAPTER V
THE HEART, BLOOD-VESSELS, AND
LYMPHATICS
THE HEART AND ARTERIES
Synopsis of Origin, Distribution, and Anastomoses
The heart is a hollow muscular organ placed within the pericardium, which
has already been described (Chapter II.). It has the form of a laterally
compressed cone, the base of which is placed superiorly, and by its pump-
like action maintains the circulation of the blood. Its position in relation
to the skeleton may be indicated as follows: It lies in an area bounded
in front by an imaginary plane passing through the middle of the
fourth dorsal vertebra, and behind by another similar plane passing behind
the tenth member of the same series. On the surface of the body its
position may be indicated by tracing out the third and sixth ribs.
Inferiorly it extends from an imaginary line drawn between the
anterior and middle thirds of the sternum to a similar line drawn
slightly in front of the junction of the sternum and ensiform cartilage.
The anterior border of the heart is convex, and runs downwards and
backwards. Its posterior border is almost straight and nearly vertical.
It is suspended in the thorax by the great vessels. On examining the
exterior of the organ, it will be found to be encircled near its upper end
by a groove—the auriculo-ventricular groove ; and it indicates on the
exterior the line of division between the auricles and ventricles—
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232 THE SURGICAL ANATOMY OF THE HORSE
chambers within the heart. Descending from this groove obliquely
downwards and forwards, one on either side, are the ventricular furrows.
They meet at the anterior border, just above the apex. In these grooves
or furrows the coronary vessels run, and in a well-nourished animal they
also contain a quantity of fat.
In the heart there are four chambers—namely, two auricles and two
ventricles. The right auricle is the upper chamber on the right side, and,
with its corresponding ventricle, forms what is sometimes referred to as
the right heart. It is made up of a main cavity, or sinus venosus, and an
ear-shaped, or auricular appendix, the latter being placed in front. The
interior of the chamber is lined by smooth endothelium, which towards
the front of the sinus venosus is raised into a number of ridges, to which
the name musculi pectinati is given. Opening into the front of the sinus
venosus is the anterior vena cava, with which, or immediately behind it
with a separate opening, the great azygos vein discharges its contents into
the auricle. The posterior vena cava opens into the back of the sinus
venosus, and at a lower level. On examining the interior of the chamber,
an elevation known as the tubercle of Lower is seen. A depression is
present on the septum between the two auricles. This is the fossa ovalis,
and it indicates the position of the foramen ovale, which in the foetus
allows the blood to pass directly from one auricle to the other. The
coronary venous sinus opens into the auricle just below the tubercle of
Lower, and its opening is guarded by a valve known as the valve of
Thebesius. The blood from the wall of the right auricle returns to the
interior of the chamber by a number of tiny apertures known as the
foramina of Thebesius. The right auricle communicates with the right
ventricle through the right auriculo-ventricular opening, and this is
surrounded by a stout ring of fibrous tissue called the zona tendinosa.
The right ventricle lies below the right auricle, and it occupies the
greater part of the front and portion of the right side of the heart. The
appearance of a transverse section through the chamber would be somewhat
crescentic in outline. The interior consists of a main cavity and a portion
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THE HEART AND ARTERIES
233
which extends upwards and to the right into the pulmonary artery. This
portion is known as the conus arteriosus. Its walls present a number of
elevations called columns carnas, of which there are several kinds. Thus
there are—(i) Columnae carnae, which are simply raised portions of the
muscular wall. (2) Muscular bands called trabecular carnas, the extremi-
ties of which are attached to the wall. A few of these pass across from
the wall of the ventricle to the interventricular septum, and these are
supposed to prevent overdistension of the ventricles. They are called
moderator bands. (3) Musculi papillares. These are blunt nipple-like
prominences, and of them there are usually three in this chamber : one on
the wall, and the two others on the septum. Radiating upwards from
each of these is a set of fibrous strings called chordae tendineae, and these
are attached superiorly to the segments of the auriculo-ventricular valve.
This valve on the right side has three flaps, hence its name tricuspid.
Return of the blood from the ventricle to the auricle during ventricular
systole is prevented by the flaps of this valve floating upwards and coming
into apposition, thus closing the orifice. The flaps are right, left, and
posterior, and their bases are attached to the zona tendinosa, their edges
hanging freely downwards into the ventricle. The chordae tendineas are
attached to these edges, and they prevent the flaps from being pushed
upwards through the opening into the auricle during systole of the
ventricle. When the ventricle contracts, the blood is thus forced up into
the conus arteriosus, forces open the pulmonary valves, and passes into the
pulmonary artery. The endocardium which lines the interior of the
chamber, is continuous with the endothelial lining of the artery, and the
vessel itself is attached to a fibrous ring, or zona tendinosa. Guarding
this opening are the semilunar valves. These are three flaps, two in front
and one behind. The bases of the flaps are strengthened by muscular
tissue, and towards the centre of each is a small hard cartilaginous body.
These are the corpora Arantii. On either side of each corpus there is a
much more delicate portion of the valve, known as the lunula. The free
edges of these flaps, as the blood is forced into the artery, are directed
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234 THE SURGICAL ANATOMY OF THE HORSE
along the lumen of the vessel. Behind each flap the wall of the vessel
presents a dilatation. These are the sinuses of Valsalva.
The left auricle is smaller than the right, and its walls are slightly
thinner and more crenated. It is also made up of a sinus venosus and an
auricular appendix, and the latter is placed posteriorly. Into the roof of
this auricle the pulmonary veins open, and they vary in number from four
to eight. Musculi pectinati are also present in this auricle. The interior
communicates with that of the left ventricle through the left auriculo-
ventricular opening, which is smaller than that on the right side. The
left ventricle is conical in shape, with the base upwards. Inferiorly it
extends to the apex of the heart. Its walls are nearly three times as thick
as those of the right ventricle. It possesses a main cavity and a conus
arteriosus, which extends upwards into the common aorta. Columnar
carnal are present, and also two musculi papillares, from which chords
tendineas extend upwards to the flaps of the valves guarding the left
auriculo-ventricular opening. This is the mitral or bicuspid valve, and it
has only two big flaps. Behind each cusp of the aortic semilunar valves
is a sinus of Valsalva. Two of these sinuses present openings, and these
are the entrances to the right and left coronary arteries, which vessels
supply the wall of the heart with blood.
The Right Coronary Artery commences at the anterior sinus. It extends
forwards, encircles the right auricular appendix, and gains the right side
of the heart, where it runs backwards along the auriculo-ventricular
groove. On arriving at the ventricular furrow it splits into two portions,
one of which continues its course backwards along the auriculo-ventricular
groove, and the other descends in the ventricular furrow.
The Left Coronary Artery runs from the left sinus of Valsalva out-
wards and to the left. Arriving at the auriculo-ventricular groove, it
runs along it until it reaches the ventricular furrow, where it splits into
two portions, one of which continues the horizontal course of the parent
vessel, and the other descends in the ventricular furrow on this side. The
coronary arteries give off a large number of collateral branches which
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THE HEART AND ARTERIES                        235
ramify on the surface of the heart, but there is said to be no anastomosis
between the main vessels or their branches.
The Pulmonary Artery is a vessel of enormous diameter which passes
upwards and backwards from the right ventricle. It runs over the left
side of the common aorta. After a course of only about three inches, it
splits into right and left divisions, which run to the corresponding lungs.
It is connected with the posterior aorta by a fibrous band known as the
ligamentum arteriosum. This is the remains of the ductus arteriosus,
a vessel which in the foetus placed the lumen of the artery in communica-
tion with that of the aorta.
The Posterior Aorta.—From the division of the common aorta this
great vessel curves upwards and backwards, to reach the inferior aspect of
the spine opposite the tenth dorsal vertebra. Between the tenth and
fourteenth vertebras it passes obliquely across the column, and, running
backwards, it leaves the thorax through the hiatus aorticus. The
oesophagus and trachea cross the right side of the arch of the vessel.
Farther backwards it is related on its right to the thoracic duct and great
azygos vein. In the thorax the posterior aorta gives off the following
branches :
I.   The last thirteen intercostal arteries—namely, from the fifth to the
seventeenth inclusive. Running upwards from the aorta, these pass over
the bodies of the vertebrae and under the dorsal cord of the sympathetic,
to reach the upper ends of the corresponding intercostal spaces. Here
each vessel splits into ascending and descending divisions. The former
gives off a spinal branch, which passes into the spinal canal to be
distributed to the structures therein, and then becomes distributed to the
muscles above the upper extremities of the ribs. The descending division
is the intercostal artery proper. These have already been described.
II.   The Broncho-CEsophageal Artery.—This leaves the posterior aorta
just in front of the point where the trachea divides. It arises in common
with the fifth intercostal artery of the right side. After a short course
downwards and backwards it divides into two portions, one of which
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236 THE SURGICAL ANATOMY OF THE HORSE
passes between the aorta and oesophagus, and splits into the two bronchial
arteries, one for each bronchus and the corresponding lung. These are
the nutrient arteries to the lungs. The second or oesophageal division
runs backwards along the superior aspect of the oesophagus, and anasto-
moses with the pleuro-oesophageal division of the gastric artery which
comes forwards through the foramen sinistrum.
In the abdominal cavity the posterior aorta passes backwards close
to the spine, along the bodies of the lumbar vertebras, being related to the
left pillar of the diaphragm and the inferior common ligament. At the
fifth lumbar vertebra it terminates by splitting into two pairs of vessels
—namely, the internal and external iliac arteries. This portion of the
posterior aorta is related on its right side to the posterior vena cava. On
its left side it is related to the left lumbar portion of the sympathetic cord,
the psoas parvus muscle, the left kidney and suprarenal body, and for
a short distance the left ureter. The branches of the abdominal portion
of the aorta are—
I.   Phrenic Arteries.—There may be two or three of these. They are
detached at the hiatus aorticus, and pass to the pillars of the diaphragm.
II.   Lumbar Arteries.—There are six or seven pairs of these vessels,
but the first four or five pairs only are branches of the aorta. Passing
upwards, each divides into two portions—namely, an upper, which gives
off a spinal branch through the intervertebral foramen to be distributed
to the structures in the spinal canal, and is then distributed to the skin
and muscles over the lumbar vertebras, and an inferior division, which
passes outwards between the transverse processes. The latter is distributed
to the abdominal muscles, and anastomoses with the circumflex iliac artery.
III.   The Cceliac Axis.—This is a large trunk detached from the
posterior aorta immediately after the latter emerges from the hiatus
aorticus. The trunk has a length of only about an inch, when it splits
into three main divisions:
A. The Hepatic Artery.—This is the right of the main divisions of
the cceliac axis, and it passes from the parent vessel forwards and down-
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THE HEART AND ARTERIES
237
wards to the right to gain the portal fissure of the liver, where it enters
this organ and supplies it with arterial blood direct from the posterior
aorta. It gives off—
i. A number of branches to the pancreas.
2. The Right Gastro-Omental Artery.—This vessel gives off pyloric
and duodenal branches, and is then continued around the greater curvature
of the stomach to anastomose with the left gastro-omental artery.
B.   The Gastric Artery.—This trunk divides after a short course into
three portions:
i. The Anterior Gastric Artery', which passes around the lesser curvature
of the stomach to its anterior surface, to which it is distributed.
2.   The Posterior Gastric Artery.—This divides near the lesser curvature
of the stomach into a number of branches, which ramify on the posterior
surface of the organ.
3.   The Pkuro-CEsophagea/ Artery.—This vessel runs forwards on the
superior surface of the oesophagus through the foramen sinistrum
to anastomose with the oesophageal division of the broncho-cesophageal
artery in the manner described. This vessel is sometimes a branch of the
splenic artery. It detaches a large number of collateral branches to the
oesophagus and the pleura?.
C.   The Splenic Artery.—This is much the largest of the three trunks.
From the division of the main vessel it runs to the left around the greater
curvature of the stomach and between it and the concave border of the
spleen. It is continued as the left gastro-omental artery, which anasto-
moses with the right gastro-omental artery, as already stated. From its
convex border it detaches a large number of branches, which penetrate
the concave edge of the spleen, whilst from its opposite side a large
number of gastric branches are detached. These pass between the layers
of the gastro-splenic omentum to the stomach, where they divide, to be
distributed to its anterior and posterior surfaces.
IV. The Anterior Mesenteric Artery.—This branch leaves the posterior
aorta at the first lumbar vertebra. It is a vessel of considerable diameter,
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238 THE SURGICAL ANATOMY OF THE HORSE
but has a length of only about an inch and a half, when it splits into three
main divisions, namely—
A.   The Left Branch.—This divides almost immediately into eighteen
to twenty branches, which run downwards between the layers of the
mesentery to the intestine. Just before reaching the intestine arches are
formed between the neighbouring branches, and from the convexities of
these arches the branches pass to each side of the intestine which they
encircle, and anastomose on its surface. The most anterior branch
anastomoses with the duodenal branch from the cceliac axis. The most
posterior anastomoses with the ileo-cascal branch of the right division of
the anterior mesenteric artery. This division of the anterior mesenteric
artery supplies the whole of the small intestine with the exception of a
portion at the beginning of the duodenum and the end of the ileum.
B.   The Anterior Branch.—This is a short vessel which divides into—
1.   The Retrograde, or Left Colic Artery, which is much the larger
division. It passes along the fourth and third portions of the large colon
in the opposite direction to that taken by the ingesta. It supplies these
portions of the large colon.
2.   The First Artery of the Small Colon.—This branch runs between the
layers of the colic mesentery, to be distributed to the first few inches of
the small colon. It anastomoses with the first branch of the posterior
mesenteric artery.
C.   The Right Branch.—This divides into the following vessels:
1.   The Ileo-Ccecal Artery, which is distributed to the last two feet of
the ileum, and which anastomoses with the division of the left branch as
stated.
2.   The Superior Ccecal Artery.—This runs over the end of the ileum
to reach the cascum along one of the longitudinal bands of which it runs
to the apex, where it anastomoses with the inferior cascal artery. From
both sides it detaches a number of collateral branches, which are
distributed to the wall of the caecum. The ileo-caecal artery is some-
times a branch of this vessel.
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THE HEART AND ARTERIES
239
3.   The Inferior Ccecal Artery.—This runs similarly along the inferior
surface of the caecum, and anastomoses with the preceding vessel as stated.
It gives off the artery to the arch of the cascum.
4.   The Right, or Direct Colic Artery.—This is a large vessel which
passes along the first and second portions of the large colon. It
courses in the same direction as the alimentary matter, and anastomoses
with the retrograde colic artery at the pelvic flexure of the great
colon.
The anterior mesenteric artery thus supplies the whole of the small
intestine (with the exception of a portion of the duodenum), the caecum,
the large colon, and a few inches of the small colon.
V.   The Renal Arteries.—There are two of these vessels, right and left.
They arise one from either side of the aorta near the first lumbar
intervertebral articulation. The right is detached slightly in advance of
the left. The left artery is the shorter, and passes outwards at right
angles to the parent vessel, direct to the hilus of the left kidney, where it
splits into a number of branches, which are distributed to the kidney.
The right artery passes above the posterior vena cava, and between it and
the psoas parvus muscle to reach the kidney. In the kidney the branches
pass between the cortex and boundary layer, where they divide and anasto-
mose, forming a number of arches, from which branches are given off to
the cortex and medulla.
VI.   The Spermatic Arteries.—There are also two of these—namely,
right and left—and they leave the posterior aorta opposite the third lumbar
intervertebral joint. Each is a long and slender vessel, which takes a
course outwards and backwards across the ureter and circumflex iliac artery
on the inferior aspect of the psoas magnus muscle. Thus it passes to the
internal abdominal ring, where it becomes one of the constituents of the
spermatic cord. It runs down the anterior portion of the cord in an
extremely tortuous manner to reach the testicle, which it supplies.
Although it is a vessel of considerable length, it does not give off any
branches until it reaches the testicle.
-ocr page 270-
24o THE SURGICAL ANATOMY OF THE HORSE
VII.   The Posterior Mesenteric Artery.—This is a branch of consider-
able size, although smaller than the anterior mesenteric artery. It leaves
the aorta opposite the fourth lumbar vertebra, and runs in a curved manner
between the layers of the colic mesentery and the mesorectum to near
the anus, where it terminates by splitting into branches which supply the
end of the intestinal canal. From the convexity of the curve twelve to
fourteen branches are detached, and these supply the whole of the small
colon with the exception of the first few inches, and also the rectum.
VIII.   The Artery to the Cord also arises direct from the posterior
aorta in some cases. It has already been described as a branch of the
external iliac artery.
IX.   The Middle Sacral Artery.—In the horse this is a very slender
vessel, and in some subjects it cannot be found. When present, it is placed
in the middle line between the two internal iliac arteries. In some animals
it is very large, and may be regarded as the continuation of the aorta into
the coccygeal region.
THE VEINS
Most of the blood of the heart is returned by the coronary veins.
These follow the course of the arteries, and discharge their contents into
the right auricle through the coronary venous sinus. Aerated blood is
returned from the lungs to the left auricle by the pulmonary veins, of
which there may be as many as eight. They arise in the capillary
networks of the lungs, and unite to form larger and larger vessels, which
follow the course taken by the branches of the pulmonary arteries and
bronchi. These veins have no valves.
The Azygos Veins.—These are described by McFadyean and others as
great and small. The larger vessel begins at the hiatus aorticus, and
passes forwards on the right side of the posterior aorta. Between the
artery and vein the thoracic duct is placed. In the thorax the vein curves
-ocr page 271-
THE VEINS
241
downwards on the right side of the aortic arch, and crossing the
oesophagus and trachea, it opens either into the anterior vena cava, or
directly into the roof of the right auricle. This vein receives the first
lumbar veins, the last thirteen intercostals of the right side, and the last
five or six intercostals of the left side. The small azygos, or left dorsal
vein, is formed by the dorsal, superior cervical and vertebral veins, and also
by the subcostal vein, into which the remaining intercostal veins of the
left side open. The vein opens into the anterior vena cava, which it
reaches by passing to the left side of the axillary artery.
The Posterior Vena Cava.—Almost all the blood from the hind limbs,
the pelvis, and the abdomen, is returned by this vessel. The external and
internal iliac veins unite to form the common iliac vein, which is placed
between the external and internal iliac arteries. The two common iliac
veins become united just above the termination of the posterior aorta
at the fifth lumbar vertebra, and slightly to the right of the median line.
Thus is formed the posterior vena cava. It runs forwards on the right
side of the posterior aorta, and to the right side of the vein are the right
kidney, suprarenal body, and ureter. Below the last dorsal vertebra
it leaves the aorta and runs between the right crus of the diaphragm and
the pancreas to reach the liver, to which it is intimately related. It
passes through the diaphragm, as already mentioned, and in the thorax
runs forwards and slightly downwards between the accessory and main
lobes of the right lung, where it is related to the right phrenic nerve.
It opens into the right auricle as described. During its course it receives—
1.   All the lumbar veins with the exception of the first pair.
2.   The spermatic veins. These are subject to a considerable amount
of variation. In some cases the two veins unite before joining the
posterior vena cava. In other cases they join the renal veins.
3.   The utero-ovarian veins in the mare, which are much larger than
the corresponding vessels in the male.
4.   The right and left renal veins, which are large vessels with thin
walls
2 H
-ocr page 272-
242 THE SURGICAL ANATOMY OF THE HORSE
5.   The hepatic veins, of which there are several, three or four of
which are usually of considerable size, the rest being very small. They
join the posterior vena cava in the anterior fissure of the liver.
6.   Two or three phrenic veins, which drain the blood from the
diaphragm, and discharge their contents into the vena cava as the latter
passes through the foramen dextrum.
The Portal Vein.—Blood from the stomach, intestines, pancreas, and
spleen is drained by vessels which contribute to the formation of this vein,
which is a vessel of considerable size. Its tributaries correspond closely
with the branches of the anterior and posterior mesenteric arteries and
the gastric and splenic divisions of the cceliac axis. The posterior
mesenteric vein unites with the splenic vein below the posterior vena
cava. The trunk thus formed is joined by the anterior mesenteric vein
behind the pancreas. The vein now passes obliquely downwards through
the pancreas in what is known as the pancreatic ring. After leaving the
ring, it inclines slightly to the right, and is joined by the anterior gastric
vein, and passes to the portal fissure of the liver. Here it divides into
three branches, which pass into the liver, where they comport themselves
after the manner of an artery by splitting up into capillaries. Other
contributions to the portal vein are the pancreatic veins and the gastro-
duodenal vein, the latter corresponding to those branches of the hepatic
artery which do not pass to the liver.
THE LYMPHATICS
The Thoracic Duct.—The lymph from the whole of the body, with the
exception of that from the right fore limb, right side of the thorax, head,
and neck, passes to the thoracic duct. This is a thin-walled tube, which
commences between the first and second lumbar vertebra? near the root of
the anterior mesenteric artery. Here there is an irregular and elongated
dilatation known as the receptaculum chyli, which is placed to the right
of the posterior aorta and between it and the right crus of the diaphragm.
-ocr page 273-
THE LYMPHATICS                                   243
The duct passes into the thorax through the hiatus aorticus, and runs
forwards slightly to the right of the middle line and between the aorta and
the great azygos vein. Opposite the sixth dorsal vertebra it inclines
downwards, runs obliquely across the left side of the oesophagus, and then
forwards on the left side of the trachea to the entrance to the thorax.
Passing over the deep face of the left scalenus muscle, it curves inwards
and then backwards, finally opening into the anterior vena cava just
behind the jugular confluence, the opening being guarded by a kind of
valve.
The duct receives—
1.   Two trunks, which are formed by the union of the efferent
vessels from the lumbar lymphatic glands. In some cases these unite
before opening into the receptaculum chyli.
2.   Two or three trunks which are formed by the union of the efferent
vessels carrying the lymph from the intestinal, gastric, hepatic, and splenic
glands.
3.   Efferent vessels from the intercostal, mediastinal, and bronchial
lymphatic glands, which join the duct in the thorax.
Other tributaries of the duct have been described in Volumes I.
and II.
The Right Lymphatic, or Small Thoracic Duct.—The lymph, from
the parts mentioned above which are not drained by the thoracic duct,
is collected by the small thoracic duct. It is only about two inches
long, and runs along the deep face of the right scalenus muscle. It
discharges its contents into the blood-stream near the jugular confluence
(according to Sisson, this duct is most frequently absent when the lymph
from these parts is carried by a number of small vessels which pass to
the thoracic duct).
The Intercostal Lymphatic Glands.—There are two rows of these small
glands, one on either side the middle line near the bodies of the dorsal
vertebrae. There is a gland corresponding to each intercostal space.
Afferent vessels to these glands come from the spinal canal, the intercostal
-ocr page 274-
244 THE SURGICAL ANATOMY OF THE HORSE
and spinal muscles, the diaphragm and the pleurae, while the efferent
vessels pass to the thoracic duct.
The Mediastinal Lymphatic Glands.—In the anterior mediastinum there
are several glands lying along the course of the intrathoracic portions of
the axillary arteries and their branches. On the left side they are related
to the trachea and oesophagus, on the right side to the trachea. Some are
placed on the superior surface of the trachea. They receive efferent
vessels from the pericardium, the heart, trachea, oesophagus, and pleurae,
and their efferent vessels pass, some to the thoracic duct, and others to the
prepectoral glands.
There are several small glands in the posterior mediastinum. They
are placed above the oesophagus. Afferents come from the oesophagus,
liver, diaphragm, mediastinum. Some efferents pass to the thoracic duct,
others to the bronchial glands and the glands in the anterior mediastinum.
The Bronchial Lymphatic Glands.—-These are numerous. There is a
group above the trachea near its division into the bronchi, others run
beneath the trachea and bronchi, whilst others run along the main divisions
of the bronchi into the lungs. The relationship of some of these glands to
the left recurrent laryngeal nerve has already been referred to in
Volume I. (see Laryngismus Paralyticus, or "Roaring"). In addition to
the vessels mentioned above, these glands receive afferent vessels from the
lungs, and efferent vessels from these glands pass to the thoracic duct, and
to the glands in the anterior mediastinum.
The bronchial glands are frequently much enlarged. The sublumbar
glands are described in Vol. III. (p. 213).
The Gastric Lymphatic Glands.—These glands follow the course of the
gastric arteries and their chief branches. There is a group at the lesser
curvature, and another near the division of the posterior gastric artery.
Some also run along the greater curvature, whilst there are others near
the pylorus. Some of their efferent vessels run to the splenic glands, but
most follow the coeliac axis, and run to the thoracic duct.
The Splenic Lymphatic Glands lie along the concave border of the
-ocr page 275-
THE LYMPHATICS
245
spleen. They receive afferent vessels from the spleen, portion of the
greater curvature of the stomach, and the left end of the pancreas. Their
efferent vessels run to the thoracic duct.
The Hepatic Lymphatic Glands lie along the course of the hepatic artery
and portal vein near the portal fissure, and their efferents pass to the
receptaculum chyli. Vessels from the anterior face of the liver join the
lymphatics of the diaphragm.
The lymphatics of the pancreas run to the hepatic and splenic
glands.
The Intestinal Lymphatic Glands are very numerous. They are placed
between the layers of the great mesentery, and are grouped near the
anterior mesenteric artery. Their afferent vessels bring the lymph from
the small intestine, and there are hundreds of them, whilst their efferents
pass to the receptaculum chyli.
The Ccecal Lymphatic Glands are in two chains, which follow the
superior and inferior cascal arteries. Efferent vessels from these glands
run to the receptaculum chyli.
The Colic Lymphatic Glands.—The glands of the great colon follow the
course of the blood-vessels, and are very numerous. Large efferent vessels
from these join those from the caecum and small intestine, and pass to the
receptaculum chyli. The glands of the small colon are in two sets. One
set runs along the line of attachment of the mesentery; the other
follows the course of the blood-vessels in the mesentery. Efferent vessels
run to the thoracic duct, and some pass to the lumbar glands.
The lymphatics of the rectum and the efferents from the glands of the
anus pass to the lumbar and internal iliac glands.
-ocr page 276-
MUSCLES OF THE TRUNK
MUSCLE
ORIGIN INSERTION
NERVE
SUPPLY
ACTION
Accelerator uri-
nae
Retractor penis
muscle and
median fibrous
raphe
Sides of penis
Pudic and sym-
pathetic
Diminishes the
calibre of the
urethra
Compressor coc-
cygis
Inner surface of
sacro-sciatic
ligament
Last sacral and
first two coc-
cygeal verte-
bras
Hemorrhoidal
Compresses tail
against the
perineum
Curvator coccy-
gis
Last two lumbar
spines ; spines
of sacrum
Lateral aspect of
coccygeal ver-
tebras
Coccygeal
Bends the tail to
side of acting
muscle
Depressor coccy-
gis
Inferior aspect of
sacrum
Coccygeal verte-
brae
Coccygeal
Depresses the tail
Erector coccygis
Sides and sum-
mits of sacral
spines
Superior surface
o f coccygeal
vertebrae
Coccygeal
Elevates the tail
Erector penis
Inferior ischiatic
spine
Crus penis
Pudic and sym-
pathetic
Erects penis by
compressing
crus
-ocr page 277-
MUSCLES OF THE TRUNK                        247
MUSCLE
ORIGIN
INSERTION
NERVE
SUPPLY
ACTION
External inter-
costal
Ribs, except last
Ribs, except first
Intercostal
Inspiratory, by-
pulling ribs
forwards
Internal intercos-
tal
Ribs and carti-
lages, except
first
Ribs and carti-
lages, except
last
Intercostal
One set of fibres
pull ribs for-
wards, other
set backwards
Intertransverse of
loins
Lumbar verte-
brae, transverse
processes
Lumbar verte-
brae, transverse
processes
Lumbar
Bends loins to
side of acting
muscle
Ischio-urethral
Ischial arch
Cowper's gland
Pudic and sym-
pathetic
Compresses ure-
thra
Lateralis sterni
First rib, outer
surface
Lateral aspect of
sternum
Intercostal
Inspiratory
Levatores costa-
rum
Dorsal vertebrae,
transverse pro-
cesses
Outer surfaces of
ribs
Dorsal
Assist in inspira-
tion
Longissimus dorsi
Ilium, sacral sur-
face ; lumbar
and dorsal
spines, and
supra - spinous
ligament
Ribs ; lumbar
vertebrae,
transverse and
articular pro-
cesses ; dorsal
vertebrae ,
transverse pro-
cesses ; cervi-
cal vertebrae,
last four trans-
verse processes
and the four
superior spines
in front of last
Cervical; dorsal;
lumbar
Extensor of spine;
assists in expi-
ration and in
elevating the
neck
-ocr page 278-
248 THE SURGICAL ANATOMY OF THE HORSE
MUSCLE
ORIGIN
INSERTION
NERVE
SUPPLY
ACTION
Obliquus abdo-
minis externus
Obliquus abdo-
minis internus
Ribs, last four-
teen, outer
surfaces ; and
tendon of latis-
simus dorsi
Ilium, external
angle; and
Poupart's liga-
ment
Linea alba ; pre-
pubic tendon;
external angle
of ilium; and
Poupart's liga-
ment
Prepubic tendon,
linea alba, and
last four or five
costal carti-
lages
Last ten inter-
costal; last
dorsal; first
two lumbar
Bend the trunk
and arch back.
If spine is
fixed, ribs are
pulled back-
wards — expi-
ration. If spine
and ribs are
fixed, abdom-
inal contents
are compress-
ed, thus assist-
ing in mictu-
rition, defalca-
tion, and par-
turition
Quadratus lum-
borum
Sacro- iliac liga-
ment
Lumbar vetebrae,
transverse pro-
cesses; and last
three ribs
Lumbar
Bends loins to
side of acting
muscle
Rectus abdomin-
is
Inferior aspect of
sternum; cos-
tal cartilages,
five to nine
Pubis by prepu-
bic tendon
Similar to oblique
muscles
Similar to oblique
muscles
Retractor ani
Superior ischiatic
spine ; inner
surface of
sacro - sciatic
ligament
Anterior edge
of external
sphincter
Hasmorrhoidal
Carries anus for-
wards and in-
verts it
Retractor costae
Transverse pro-
cesses of first
three lumbar
vertebrae
Last rib, posterior
surface
Last dorsal; first
lumbar
Assists in expira-
tion
Retractor penis
First three coccy-
geal vertebrae
Penis
Pudic and sym-
pathetic
Retracts penis
-ocr page 279-
TRUNK                       249
MUSCLES OF THE
MUSCLE
ORIGIN
INSERTION
NERVE
SUPPLY
ACTION
Semispinalis of
back and loins
Sacrum, lateral
lip; lumba r
vertebras, ar-
ticular proces-
ses; dorsal ver-
tebras, trans-
verse processes
Lumbar and dor-
sal vertebral
spines
Dorsal and lum-
bar
Extensor of
spine; one
muscle acting
inclines spine
to that side
Serratus anticus
Second to thir-
teenth dorsal
vertebral spines
Anterior borders,
and outer sur-
faces of fifth to
thirteenth ribs
Dorsal
Inspiratory
Serratus posticus
Eleventh dorsal
to second lum-
bar vertebral
spines
Posterior borders,
and outer sur-
faces of last
eight or nine
ribs
Dorsal
Expiratory
Sphincter ani ex-
tern us
Root of tail
Perineal fascia
Haemorrhoidal
To maintain
anus closed
' except during
defalcation
1
Sphincter ani in-
ternus
Circular ring
around rectum
Hasmorrhoidal
Transversalis ab-
dominis
Last ten ribs,
lower extremi-
ties and carti-
lages; trans-
verse processes
of lumbar ver-
tebrae
Ensiform carti-
lage and linea
alba
Similar to oblique
muscles
Similar to oblique
muscles
Transversalis
costarum
First two lumbar
transverse pro-
cesses and an-
terior borders
of ribs
First to four-
teenth ribs,
posterior
edges; and
seventh cervi-
cal transverse
process
Dorsal
Depresses ribs
2 I
-ocr page 280-
250 THE SURGICAL ANATOMY OF THE HORSE
MUSCLE
ORIGIN
INSERTION
NERVE
SUPPLY
ACTION
Transversus peri-
naei
Tuber ischii
Mesial line of
perineum and
origin of accel-
erator urina;
Pudic and sym-
pathetic
Dilates bulbous
portion of ure-
thra
Triangularis
sterni
Superior aspect of
sternum; from
second to eight
costal carti-
lages
Costal cartilages,
and aponeuro-
sis over inter-
nal intercostal
muscles
Intercostal
Pulls cartilages
backwards
Wilson's
Aponeurotic fas-
ciculi to walls
of pelvis
Cowper's gland
and accelerator
urinae
Pudic and sym-
pathetic
Compressor of
m e m b r a n ous
portion of ure-
thra
-ocr page 281-
INDEX
i
Arteries—continued
inferior labial, i. 58, 134
innominate, i. 131
intercostal, iv. 68, 235
internal iliac, iii. 189
mammary, iv. 70
maxillary, i. 11, 133,
136 ...
pudic, iii. 190
thoracic, iv. 70
interosseous of forearm, ii.
15,36,174
ischiatic, iii. 191
labial, i. 134
lachrymal, i. 137
large metatarsal, iii. 10, 17,
38, 202
lateral coccygeal, iii. 191
sacral, iii. 190
lingual, i. 46, 134
lumbar, iv. 236
mastoid, i. 132
maxillo-muscular, i. 6, 56,
135
median-spinal, i. 133
meningeal, i. 138
metacarpals, ii. 24, 37, 175,
176
middle coccygeal, iii. 191
sacral, iv. 240
nasal, i. 135, 138
nutrient to femur, iii. 197
to humerus, ii. 171
to tibia, iii. 200
obturator, iii. 193
occipital, i. 114, 132
occipito-muscular, i. 133
ophthalmic, i. 137
ovarian, iv. 207
palatine, i. II, 138
palmar interosseous, ii. 37,
176
perforating tarsal, iii. 24,
119, 201
Abdomen, iv. 106
Abdominal tunic, iv. 63, 107
wall, iv. 107
wounds, iv. 112
Alar cartilage, i. 4
Alveolar fistula, i. 36
Ampulla of rectum, iv. 215
Amputation of penis, iv. 202
of tongue, i. 46
of uterus, iv. 221
Annular cartilage, i. 123
Anorchids, iv. 190
Anus, injuries to, iv. 135
Arachnoid membrane, iv. 153
Arteries :
angular, i. 41, 135
anterior abdominal, iv. 70
deep temporal, i. 137
dorsal of penis, iii. 196
mesenteric, iv. 237
radial, ii. 36, 172
tibial, iii. 24, 119, 199
aorta (posterior), iv. 235
artery to biceps, ii. 23, 172
to cord, iii. 194 ; iv.
240
to corpus cavernosum,
iii. 193
to latissimus dorsi, ii.
22, 169
to plantar cushion, ii.
178
articular to stifle, iii. 197
asternal, iv. 70
auricular, i. 124, 135
axillary, i. 130 ; ii. 22, 167
basilar, i. 133
brachial, ii. 22, 170
broncho-cesophageal, iv. 23 5
buccal, i. 138
carotid, i. 19, 75, 131
central retina, i. 137
cerebro-spinal, i. 93, 133
circle of Willis, i. 133
Arteries—continued
circumflex, ii. 74, 169
iliac, iii. 194
of coronary cushion,
iv. 18
of toe, iv. 18
coccygeal, iv. 151
cceliac axis, iv. 236
coronary, iv. 234
circle, ii. 178
deep humeral, ii. 170
digital, ii. 6, 25, 39, 177 ;
iii. 18 ; iv. 12, 17
direct colic, iv. 239
dorsal, i. 130 ; iv. 69
interosseous, ii. 24, 37,
175
dorso-cervical, i. 131
external carotid, i. 6
iliac, iii. 162, 193
mammary, iv. 71
pudic, iii. 196 ; iv.
no, 195, 227
thoracic, ii. 168 ; iv.
I}.
femoral, iii. 195
femoro-popliteal, iii. 197
first artery of small colon,
iv. 238
gastric anterior, iv. 237
pleuro- oesophageal, iv.
237
posterior, iv. 237
gluteal, iii. 192
great meningeal, i. 136
hepatic, iv. 142, 236
ileo-ca;cal, iv. 238
ilio-femoral, iii. 192
ilio-lumbar, iii. 192
incisor, i. 87
inferior cascal, iv. 238
cervical, i. 21, 131 ; ii.
168 ; iv. 68
dental, i. 136
251
-ocr page 282-
THE SURGICAL ANATOMY OF THE HORSE
Bones—continued
seat of spavin, iii. 7
sesamoids, ii. 38, 65
small sesamoid, iv. 14
sternum, iv. 99
suffraginis, ii. 7, 67
third trochanter, iii. 2, 52
tibia, iii. 60
tibial crest iii. 12, 61
tuber ischii, iii. 2, 46
ulna, ii. 49
Botryomycosis of udder, iv. 229
Bourgelat splint, ii. 48
Breakdown, ii. 132
Broad ligaments (of uterus), iv.
214
Bruised frog, iv. 34
heel, iv. 34
sole, iv. 33
Bulb of urethra, iv. 198
Bulbs of frog, iv. 3
of plantar cushion, iv. 9
Bursa;, ii. 117
Buttress foot, iv. 59
Cascum, iv. 128
Calculi, iv. 164
Canine teeth, i. 29
Canker, iv. 44
Capped hock, iii. 144
Cariniform cartilage, iv. 99
Cartilage of prolongation, ii. 18
Cartilaginous plexus, iv. 19, 20
Caruncula lachrymalis, i. 117
Castration, iv. 177
by torsion, iv. 182
complications and sequela;,
iv. 184
covered operation, iv. 183
ligaturing bloodvessels, iv.
181
of cryptorchids, iv. 191
Bang's method, iv. 192
recumbent operation,iv. 179
standing operation, iv. 178
Caudal myotomy, iv. 150
Cerebral hemispheres, i. 15
Cervical canal, iv. 214
Chestnut, ii. 6
Choking, i. 52
Chondroids, i. 80
Chorda; tendinea;, iv. 233
Circumflex artery of coronary
cushion, iv. 18
of toe, iv. 18
vein, iv. 19
Circumvallate papillae, i. 45
Clitoris, iv. 216
Arteries—continued
perpendicular of pastern, ii.
16, 177 ; iii. 18
pharyngeal, i. 134.
phrenic, iv. 236
plantar, ii. 16 ; iv. 13, 18
arch, iv. 18
interosseous,iii. 25, 38,
201
plexus, iv. 8
popliteal, iii. 29, 102, 198
posterior abdominal, iii. 196
auricular, i. 84, 135
deep temporal, i. 137
dorsal of penis, iii. 193
mesenteric, iv. 24.0
radial, ii. 6, 2 3, 36, 172
tibial, iii. 24, 32, 120,
199
prehumeral, ii. 23, 170
preplantar, ii. 16; iv. 12,
17
prepubic, iii. 195
prevertebral, i. 132
profunda, iii. 196
pulmcnary, iv. 233, 235
ramus dorsalis (dorsal spinal),
iv. 68
ventralis, iv. 69
renal, iv. 160, 239
retrograde, i. 19, 133 ; iii.
25, 200 ; iv. 238
right gastro-omental.iv. 237
saphena, iii. 6, 197
scapulo-humeral, ii. 169
semilunar anastomosis, iv.
12, 18
spermatic, iv. 173, 193, 239
spheno-palatine, i. 138
spinal, iv. 155
splenic, iv. 237
staphyline, i. 49, 138
subcostal, iv. 70
subcutaneous abdominal, iii.
196 ; iv. 109, 195, 227
submaxillary, i. 44, 58, 134
submental, i. 134
subscapular, ii. 168
superficial temporal, i. 124,
'33. 135
superior caecal, iv. 238
cervical, i. 130
dental, i. 41, 138
labial, i, 134
supra-orbital, i. 137
suprascapular, ii. 22, 168
tarsal arch, iii. 25
thyroid, i. 132
Arteries—continued
thyro-laryngeal i. 71, 132
transverse facial, i. 6, 124,
135 ,
tympanic, i. 136
ulnar, ii. 23, 171
umbilical, iii. 189
unnamed, ii. 15 ; iii. 18, 25
utero-ovarian, iv. 208
vertebral, i. 19, 21, 130
vesico-prostatic, iii. 190
Arytenectomy, i. 69, 72
Arytenoid cartilages, i. 5, 14, 64
Auricles, iv. 232
Auricular appendix, iv. 232, 234
Auriculo-ventricular valve, iv.
233
Back, iv. 62, 87
Balanitis, iv. 195
Ballooning of vagina, iv. 210
Barbs, i. 4, 12
Bars, iv. 2
of frog, iv. 3
Basilar process, iv. 13
Bicipital tuberosity, ii. 46
Bicuspid valve, iv. 234
Bishopped teeth, i. 32
Bones :
angle of croup, iii. 2, 44
of haunch, iii. 2, 44
astragalus, iii. 21, 66
calcis, iii. f.j
carpal, ii. 52
coccygeal vertebra;, iv. 148
corona;, ii. 68
cuneiform magnum, iii. z\,
parvum, iii. 70
external malleolus, iii. 13, 63
femur, iii. 5 1
fibula, iii. 65
great trochanter, iii. 2, 53
humerus, ii. 44 ; iv. 63
ileum, iii. 42
internal malleolus, iii. 21, 63
ischium, iii. 45
metacarpals, ii. 55, 57
metatarsals, iii. 82
navicular, iv. 12, 14
patella, iii. 3, 12, 58
pedal, iv. 11
pisiform, ii. 53
pubis, iii. 46
radius, ii. 46
sacrum, iv. 148
scaphoid, iii. 2\, 68
scapula, ii. 40 ; iv. 63
-ocr page 283-
INDEX
253
Coffin bone, iv. 11
joint, iv. 1 5
Colon, iv. 129
Colotomy, iv. 136
Columnas carnae, iv. 233
Commissures of frog, iv. 3
Complementary cartilage, ii. 110
Conchal cartilage, i. 122
Conus arteriosus, iv. 233
medullaris, iv. I 54.
Coracoid process, ii. 40
Cornea, i. 120
Corns, iv. 2, 32
Cornua of uterus, iv. 213
Coronary cushion, iv. 2, 6
plexus, iv. 19, 20
Corono-glandis, iv. 198
Coronoid fossa, ii. 44
Corpora arantii, iv. 233
nigra, i. 120
Corpus callosum, i. 15
cavernosum, iv. 198
spongiosum, iv. 198
Cremasteric layer, iv. 183
Cricoid cartilage, i. 5, 64
Croup, iv. 148
Crust, iv. 1
Cryptorchids, iv. 190
Crystalline lens, i. 120
Curb, iii. 147
Cutigeral groove, iv. 26
Cystic ovaries, iv. 211, 213
testicles, iv. 194
Cysts :
anal, iv. 139
rectal, iv. 139
vagin.'l, iv. 225
vulval, iv. 225
Dartos, iv. 183
Deltoid tubercle, ii. 44
Dental caries, i. 37
follicle, i. 24
pulp, i. 24
sac, i. 31
Dentigerous cysts, i. 126 ; iv. 194
Dentine, i. 23
Descemets membrane, i. 1 20
Desmotomy, ii. 136
Diaphragm, iv. 62, 72
Digital vein, iv. 20
Discomyces equi, iv. 186
Drawn nail, iv. 37
Duct of Wirsung, iv. 143
Duodenum, iv. 128
Dura mater, i 16 ; iv. 153
Ear, i. 122
Ectropion, i. 117
Emasculation, iv. 177
Enamel, i. 24
Endocardium, iv. 233
Ensiform cartilage, iv. 100
Enterocentesis, iv. 131
Entropion, i. 116
Epididymis, iv. 174, 182, 192
Epiglottis, i. 14
Epiphora, i. 119
Ergot, ii. 7
Eustachian tube, i. 14, 18, 78
Examination of female genital
tract, iv. 217
Exostoses, ii. 41, 70
External abdominal ring, iv. 191
Extirpation of mammary gland,
iv. 229
Eye, i. 116
Eyeball, i. 120
Fallopian tube, iv. 206, 207
False nostril, i. 4
quarter, iv. 27
Falx cerebri, i. 1 5
Fauces, i. 14, 17
Fibro-cartilage, iv. 10
Filiform papillae, i. 45
Fistula of anus, iv. 139
of bowel, iv. 130
of rectum, iv. 1 39
of urethra, iv. 171
Fistulous withers, iv. 89
Flexor perforans, iv. 52
Foramen dextrum, iv. 74
incisor, i. 9, 87
infra-orbital, i. 4
magnum, i. 16, 45
mental, i. 90
ovale, iv. 232
palatine, i. 12
preplantar, iv. 12
sinistrum, i. 5 1 ; iv. 74
Foramina :
great sacro-sciatic, iii. 86
lesser sacro-sciatic, iii. 86
Fossa ovalis, iv. 232
Fractures :
angle ol ilium, iii. 7
coronaa, ii. 69
croup, iv. 149
deferred, iii. 63
dorsal vertebrae, iv. 90
femur, iii. 56
humerus, ii. 45
innominate, iii. 47
lumbar vertebrae, iv. 147
metacarpals, ii. 58
Fractures—continued
metatarsals, iii. 84
patella, iii. 59
pedal bone, iv. 59
pisiform, ii. 54
radius, ii. 48
ribs, iv. 97
scapula, ii. 2, 42
sesamoids, ii. 66
spontaneous, ii. 69
sternum, iv. 99
tail, iv. 150
tarsus, iii. 71
tibia, iii. 63
ulna, ii. 50
Frog, iv. 2, 3
(sensitive), iv. 7
stay, iv. 4
Gasrtner, canal of, iv. 207
Galactophorous or lactiferous
sinus, iv. 227
Gathered nail, iv. 35
Genital organs, iv. 172
Glans penis, iv. 197, 198
Glenoid cavity, ii. 40
Glomes, iv. 3
Glottis, i. 14
Graafian follicles, iv. 207
Gubernaculum testis, iv. 189
Gunther's catheter, i 81
Gustatory bodies, i. 45
Guttural pouches, i. 15, 18,
77
Haematoma (vagina wall), iv. 225
Hard palate, i. 9
Heart, iv. 231
Heels, iv. 1,2
Hernia, diaphragmatic, iv. 75
inguinal, iv. 122, 183
scrotal, iv. 122, 183
umbilical, iv. 120
ventral, iv. 115
Herniotomy, iv. 124
Hiatus aorticus, iv. 74
Hoof, iv. I
Horn tissue, iv. 5
tumours, iv. 23
Horns (of uterus), iv. 213
Hydatids of Morgagni, iv. 208
Hydrocele, iv. 175
Hymen, iv. 216
Hyovertebrotomy, i. 6, 18, 82
Ileum, iv. I 28
Incisor teeth, i. 26
Infundibulum, i. 26
-ocr page 284-
254 THE SURGICAL ANATOMY OF THE HORSE
Inguinal canal, iv. 120, 191, 192,
195 .
nerves, iv. 195
ring, iv. 183
Injuries to sheath, iv. 195
to vulva, vagina, and uterus,
iv. 218
Interarticular meniscii, iii. 96
Internal abdominal ring, iv. 192
193
Interosseous ligament, iv. 1 5
Interventricular septum, iv. 233
Intestines, iv. 128
Intravenous injection, i. 140
Inversion of uterus, iv. 218
reposition, iv. 219
Coculet's method, iv.
220
of vagina, iv. 223
Hewetson's case, iv.
224
treatment of, iv. 224
Iris, i. 120
Jejunum, iv. 128
Joints :
chondro-sternal, iv. 104
coffin, iv. I 5
costo-central, iv. 103
costo-chondral, iv. 104
costo-transverse, iv. 103
coxo-femoral (hip), iii. 88
diseases of:
coxo-femoral (hip),
iii. 132
false hip lame
ness, iii. 1 32
luxation, iii. 92
traumatic arthri-
tis, iii. 91
true hip lameness,
iii. 130
elbow, ii. 78
capped, ii. 84
dry arthritis, ii.
luxation, ii. 80
traumatic arthri-
tis, ii. 82
fetlock, ii. 34, 38, 101
articular wind-
gall, ii. 108
brushing, ii. 107
knuckling, ii. 104
lameness, ii. 106
luxation, ii. 103
hock :
bog spavin,iii. 127
Joints—continued
diseases of hock :
capped hock, iii.
IH..
curb, iii. 147
luxation, iii. 126
traumatic arthri-
tis, iii. 123
wrenched, iii. I 23
knee, ii. 87
bent, ii. 91
broken, ii. 94
Cherry's opera-
tion, ii. 97
contused, ii. 92
dry arthritis, ii.
98
hygroma, ii. 92
speedy cutting, ii.
9?
pastern, ii. 110
ringbone, ii. 111
traumatic arthri-
tis, ii. 115
sacro-iliac, luxation,
iii. 87
shoulder, ii. 72
abscess, ii. 78
arthritis, ii. 77
luxation, ii. 75
wrenched, ii. 76
stifle :
gonitis, iii. 96,
108
luxation of pa-
tella, iii. 103
traumaticinjuries,
iii. 107
hock, iii. 111
interphalangeal, iv. I 5
intervertebral, iv. 101
ischio-pubic svmphysis, iii.
88
sacro-iliac, iii. 85
stifle, iii. 94
Jugular furrow, i. 7
Keraphyllocele, iv. 24
Keratogenous membrane, iv. 5
Keratoma, iv. 23
Keratophyllocele, iv. 24
Kidneys, iv. 160
Knee thoroughpin, ii. 121
Labia (of vulva), iv. 216
Lachrymal canal, i. 119
duct, i. 97, 119
sac, i. 119
Lactiferous ducts, iv. 227
Lacuna of frog, iv. 2
Laminae of frog, iv. 2, 3
sensitive, iv. 78
Laminal tissue, iv. 8
Laminitis, iv. 9, 38
Laparotomy, iv. 133
Laryngismus paralyticus, i. 5,
68
Laryngitis, i. 69
Laryngotomy, i. 70
Larynx, i. 5, 63
Lateral cartilage, ii. 2, 8 ; iv. 9,
10
plexus, iv. 20
Left auricle, iv. 234
Ligaments :
anterior common of hock,
iii. 116
costo - transverse, iv.
103
antero-lateral of corono-
pedal joint, iv. 13,15
arciform, ii. 50
arcuate, iv. 74
astragalo-metatarsal, iii. 11 3
-scaphoid, iii. 1 13
bladder of, iv. 162
calcaneo-astragaloid, iii. 11 3
-cuboid, iii. 114
-metatarsal, iii. 36,
114, 147
capsular of hip, iii. 90
coronary, iii. 96
costo-vertebral, iv. 103
cotyloid, iii. 42, 91
crucial, iii. 28, 98
cuboido-cunean, iii. 112
-scaphoid, iii. 112
external lateral of stifle, iii.
14, 28, 99
femoro-patellar capsule, iii.
97
great suspensory, iii. 14, 22
hepatic, iv. 142
inferior common, iv. 102
ilio-sacral, iii. 85
sesamoidean, ii. 34,103
interarticular, iv. 103
intercunean, iii. 112
internal lateral of stifle, iii.
28, 99
interosseous, iv. 15
inter-sesamoidean, ii. 39
interspinous, iv. 102
lateral patellar, iii. 97
laterals of hock, iii. 114
latum pulmonis, iv. 75
-ocr page 285-
INDEX
Lymphatics—continued
pharyngeal, i. 144
prepectoral, i. 143
prescapular, ii. 184
right lymphatic, iv. 243
splenic, iv. 243, 245
submaxillary, i. 5, 144
thoracic duct, iv. 242
small, iv. 243
Malignant growths of udder, iv.
229
Mammary glands, iv. 226
extirpation of, iv. 229
injuries to, iv. 228
nerve-supply, iv. 228
Meatus urinarius, iv. 216
Meckel's ganglion, i. 49
Medulla oblongata, i. 15
Membrana nictitans, i. 118
Mesochorium, iv. 189
Mesosalpinx, iv. 207
Mesovarium, iv. 207
Micrococcus of Johne, iv. 186
Mirror of Helmont, iv. 73
Mitral valve, iv. 234
Molar teeth, i. 27
Monorchids, iv. 190, 193
Muscles:
accelerator urina;, iv. 246
adductor magnus, iii. 216
parvus, iii. 215
anconeus, ii. 188
anterior deep and superficial
pectorals, iv. 67
arytenoideus, i. 66
aryteno-pharyngeus, i. 147
azygos uvulae, i. 49, 147
biceps, ii. 11, 20, 188
femoris, iii. 3, 12, 14,
218
brachialis anticus, ii. 12,
189
buccinator, i. 58, 147
caput, ii. 2, 12, 19, 188 ;
iv. 63
cervico-auricularis, i. 123,
H7
coccygeal, iv. 151
complexus, i. 20, 147
compressor coccygis, iv. 246
coraco - humeralis, ii. 19,
188
cremaster, iv. 173, 174
crico-arytenoideii lateral, i.
66
posterior, i. 66
-pharyngeus, i. 67, 148
255
Muscles—continued
crico-thyroid, i. 66
curvator coccygis, iv. 246
deep gluteus, iii. 217
deltoid, ii. 2, 11, 188
depressor coccygis, iv. 246
labii inferioris, i. 58,
superioris, i. 148
digastricus, i. 58, 148
dilator nares, i. 148
pupilla;, i. 148
erector coccygis, iv. 246
penis, iv. 246
extensor brevis, iii. II, 17,
2I9
metacarpi magnus, ii.
3, 12, 20, 190
obliquus, ii. 14,
190
pedis, ii. 3, 13,36,190;
iii. 4, 16, 218
suffraginis, ii. 3, 13,36,
190
external intercostal, iv. 66,
2+7
flexor accessorius, iii. 7, 23,
220
metacarpi externus, ii.
3, H. l89
internus, ii. 20,
37, 18?
medius, ii. 20, 37,
189
metatarsi, iii. 4, 30,
218
perforans, ii. 4, 6, 21,
36, 189 ; iii. 10, 15,
24, 220
perforatus, ii. 4, 6, 21,
36, 189; iii. 9, 13,
I5'2I9...
gastrocnemius, iii. 9. 15, 23,
30, 219
gemelli, iii. 217
genio-glossus, i. 148
-hyo-glossus, i. 46, 149
-hyoid, i. 46, 90,
I+9
gracilis, iii. 5, 22, 215
hyo-epiglottideus, i. 64
-glossus, i. 46, 149
-pharyngeus, i. 149
iliacus, iii. 216
infraspinatus, ii. I, II, 189
internal intercostal, iv. 66,
247
interossei, ii. 190; iii. 220
Ligaments—continued
posterior common of hock,
iii. 116
of stifle, iii. 99
costo- transverse, iv.
103
postero-lateral of corono-
pedal joint, iv. 15
Poupart's, iv. 121
pubio-femoral, iii. 42, 89,
130 _
sacro-iliac, iii. 85
-sciatic, iii. 85
scaphoido-cunean, iii. 112
splenic, iv. 144
stellate, iv. 103
straight patellar, iii. 13, 22,
28, 97, 13+
subcarpal (check), ii. 4, 10,
18, 90
subflava, iv. 102
superior common, iv. 102
ilio- sacral, iii. 85
sesamoidean (suspen-
sory), ii. 5, 10, 18,
102
supraspinous, iv. 102
suspensory of prepuce, iv.
107
tarso-metatarsal, iii. 114
teres, iii. 42, 90, 130
transverse, iii. 42, 91
uterine, iv. 126
Ligamentum nucha;, i. 18, 108
Liver, iv. 141
Loins, iv. 144
Loose waii, iv. 27
Lumbo-costal arch, iv. 74
Lungs, iv. 79
Lunula, iv. 233
Lymphatic glands :
deep inguinal, iii. 6, 213
iliac, iii. 213
popliteal, iii. 212
precrural, iii. 212
sub-lumbar, iii. 213
superficial inguinal, iii. 213
Lymphatics :
brachial, ii. 184
bronchial, iv. 243, 244
cascal, iv. 245
colic, iv. 245
gastric, iv. 243, 244
hepatic, iv. 243, 245
intercostal, iv. 243
. intestinal, iv. 243, 245
lumbar, iv. 243
mediastinal, iv. 243, 244
-ocr page 286-
256 THE SURGICAL ANATOMY OF THE HORSE
Muscles—coTitinued
intertransverse of loins, iv.
247
of neck, i. 20, 149
ischio-urethral, iv. 247
lateralis sterni, iv. 66, 247
latissimus dorsi, ii. 19, 187 ;
iv. 63
levator anguli scapulas, i. 20;
ii. 186
labii superioris aliqui
nasi, i. 43, I49
superioris pro-
prius, i. 43, 149
menti, i. 149
palati, i. 49, 150
palpebral superioris, i.
150
levatores costarum, iv. 65,
H7.
longissimus dorsi, iv. 64,
247
longus colli, i. 19
lumbricales, ii. 190 ; iii 220
masseter, i. 43, 1 50
mastoido-auricularis, i. 123,
150
mastoido-humeralis, i. 20,
150, ii. 2, 187
middle gluteus, iii. 2, 217
mylo-hyoid, i. 45, 150
obliquus abdominis exter-
nus,iv. 63, 109,
248
internus, iv. 108,
192, 248
capitis inferioris, i. 6,
superioris, i. 6,
oculi inferioris, i. I 5 I
superioris, i. 15 1
obturator externus, iii. 216
internus, iii. 217
occipito-styloid, i. 83, 15]
orbicularis oris, i. 151
palpebrarum, i. 1 5 l
palato glossus, i. 15 1
-pharyngeus, i. 48,
panniculus carnosus, iv. 107
parieto-auricularis, i. 123,
parotido auricularis, i. 55,
I23> '52..
pectineus, iii. 215
pectoral, ii. 5, 186
peroneus, iii. 4, 13, 16,219
Muscles—continued
popliteus, iii. 23, 29, 219
posterior deep pectoral, iv.
63, 69
superficial pectoral, iv.
67
psoas magnus, iii. 216 ; iv.
73, 144, 146
parvus, iv. 73, 145,
pterygoideus, i. 152
pterygo-pharyngeus, i. 152
pyriformis, iii. 217
quadratus femoris, iii. 216
lumborum, iv. 145,
248
quadriceps extensor cruris,
iii. 3, 12, 14, 218
rectus abdominis, iv. 63,
108, 248
capitis, i. 18, 153
femoris, iii. 218
oculi, i. 153
parvus, iii. 218
retractor, i. 153
ani, iv. 248
costse, iv. 248
penis, iv. 248
rhomboideus, i. 20 ; iii.
l8Z
sartorius, iii. 5,215
scalenus, i. 21, 154
scapulo-humeralis gracilis, ii.
188
scapulo-ulnaris, ii. 19, 188
scuto auricularis, i. 123,
semimembranosus, iii. 6,
216
semispinalis of back and
loins, iv. 65, 249
colli, i. 154
semitendinosus, iii. 216
serratus amicus, iv. 64, 249
magnus, ii. 186 ; iv.
63
posticus, iv. 64, 249
soleus, iii. 219
sphincter ani externus, iv.
249
internus, iv. 249
pupillae, i. 154
splenius, i. 20, 155
stapedius, i. 154
sterno-maxillaris, i. 22, 58,
-thyro-hyoideus, i. 22,
'55
Muscles—continued
stylo-glossus, i. 47, 155
-hyoid, i. 77, 155
-maxillaris, i. 22, 58,
155
-pharyngeus, i. 156
subscapulo-hyoideus, i. 21,
156
subscapularis, ii. 18, 187
superficial gluteus, iii. I, 3,
217
supraspinatus, ii. 1, 11,
189
temporal, i. I, 156
tensor palati, i. 49, 156
tympani, i. 156
vaginae femoris, iii. 1,
3, 217
teres major, ii. 19, 187
minor, ii. 188
thyro-arytenoid, i. 66, 156
-hyoid, i. 60, 157
trachealis, i. 117
trachelo-mastoid, i. 20, 157
transversalis abdominis, iv.
109, 249
costarum, iv. 64, 249
transversus perinsei, iv. 250
thoracis, iv. 68
trapezius, i. 20, 157 ; ii.
187 ; iv. 63
triangularis sterni, iv. 66,
250
triceps extensor cubiti, ii.
2, 12, 19, 188
ulnar accessorius, ii. 15, 36
vastus externus, iii. 218
internus, iii. 2 18
Wilson's, iv. 250
zygomatico - auricularis, i.
123, 157
zygomaticus, i. 58, 157
Musculi papillares, iv. 233
Musculo-spiral groove, ii. 44
Myositis of gluteal muscles, iii.
93
Nail bound, iv. 37
puncture, iv. 37
Nares, i. 10, 13, 17
Nasal chamber, i. 9, 11, 17
fossae, i. 2
Navicular bone, iv. 12, 14, 52
disease, iv. 53
Nerve paralysis :
anterior crural, iii. 160
brachial plexus, ii. 139
external popliteal, iii. 169
-ocr page 287-
INDEX
257
Nerve paralysis—continued
gluteal, iii. 175
great sciatic, iii. 166
internal popliteal, iii. 170
musculo-spiral (radial), ii.
146
obturator, iii. 172
suprascapular, ii. 142
Nerves :
anterior crural, iii. 159
tibial, iii. 4, 20, 181
auricular, i. 55, 124
bell, iii. 139
biceps, ii. 29, 156
brachial plexus, ii. 26, 74,
139
cardiac, iv. 81
circumflex, ii. 27, 74, 141
coraco-humeralis, ii. 29, 156
cubito-plantar, ii. 151
cutaneous of back, iv. 71
digital, ii. 17, 39, 162 ; iii.
20
dorsal, iv. 71
external popliteal, iii. 19,
30, 103, 164
saphena, iii. 19, 121,
165
thoracic, iv. ill
fifth, i. 42, 128
glosso-pharyngeal, i. 46
gluteal, iii. 174
great sciatic, iii. 164
hypoglossal, i. 46
iliaco-muscular, iii. 158
inferior thoracic, ii. 140
infra-orbital, i. 3, 42
intercostal, iv. 71, 72
internal popliteal, iii. 30,
103, 170
saphena, iii. 6, 103
laryngeal, i. 19, 67
latissimus dorsi, ii. 27, 141
lingual, i. 46
lumbo-sacral plexus, iii. 157
median, ii. 28, 35, 154
musculocutaneous, ii. 29
157; iii. 4, 20,
180
-spiral, ii. 27, 144
obturator, iii. 171
olfactory, i. 11
peroneal-cutaneous, iii. 19,
165
pes anserinus, i. 3, 44
phrenic, i. 94; iv. 62, 81
plantar, ii. 17,30, 37, 160;
iii. 20, 27, 187
Parovarium, iv. 207
Pedal bone, iv. 11
Penis, iv. 180, 194, 197
amputation of, iv. 202
wounds and tumours on,
iv. 201
Pericardium, iv. 81
Periople, iv. I
Perioplic ring, iv. 37
Periosteotomy, ii. 63
Peripheral vein, iv. 19
Peritoneum, iv. 125
Pharynx, i. 13
Phlebitis, i. 141
Phlebotomy, i. 7, 141
Pia mater, iv. 143
Plantar arch, iv. 18
artery, iv. 18
cushion, iv. 9
foramen, iv. 13
plexus, iv. 8
reticulum, iv. 8
Pleurae, iv. 75
Podophyllous tissue, iv. 7, 8
Poll-evil, i. 6, 18, 108
Postero-lateral ligament of corono-
pedal joint, iv. 15, 16
Prepuce, iv. 194
Preputial orifice, iv. 195
Prolapse :
anus, iv. 137
bladder, iv. 168
rectum, iv. 137
Pumice foot, iv. 43
Punctio intestini, iv. 131
perinealis, iv. 167
vesica, iv. 167
Punctalachrymalia, i. 117
Pyramidal disease, iv. 59
Pyro-puncture, ii. 64
Quarters, iv. I
Quittor, iv. 10, 16, 46
Radio-ulnar arch, ii. 47
Ranula, i. 60
Recto genital pouch, iv. 215
Rectum, iv. 129
exploration of, iv. 140
Recumbent operation (castra-
tion), iv. 179
Removal of ovaries, iv. 208
Reticulum processigerum, iv. 19
Retrossal process, iv. 13
Ribs, iv. 62, 95
" Rig," iv. 190
Right auricle, iv. ^32
ventricle, iv. 232
Nerves—continued
pneum gastric, i. 19
posterior tibial, iii. 26, 32,
121, 176
radial, ii. 27, 144
recurrent, i. 67, 75
spinal accessory, i. 21
subcutaneous thoracic, ii.
27, 140 ; iv. 72
subscapular, ii. 28, 141
subzygomatic, i. 55
suprascapular, ii. 26, 142
sympathetic, i. 19, 75
teres major, ii. 27, 141
vagus, i. 19, 22, 75 ; iv. 62
Neurectomy :
anterior tibial, iii. 182
digital, ii. 165
median, ii. 157
plantar, ii. 163 ; iv. 58, 59
posterior tibial, iii. 178
tibial, iv. 59
ulnar, ii. 153
Occlusion of vagina or vulva, iv.
226
CEsophagotomy, i. 7, 2 1, 54
CEsophagus, i.4, 19, 21 ; iv. 60
Olecranon fossa, ii. 44
process, ii. 50
Olfactory fossa;, i. 16
Omenta, iv. 125
Oophorectomy, iv. 208
Organs of Meyer, i. 46
Os pedis, iv. 11
uteri, iv. 210
externum, iv. 214
internum, iv. 214
Ossific tentorium, i. 16
Ostium abdominale, iv. 125, 207
praeputiale, iv. 195
uterinum, iv. 208
Ova, iv. 206
Ovarian artery, iv. 207
Ovaries, iv. 206
Ovariotomy, iv. 208
Over-reach, iv. 21
Oviducts, iv. 207
Ovulation fossa, iv. 207
Palate, i. 13
Pancreas, iv. 143
Papillae foliatae, i. 46
Paracentesis abdominis, iv! 114
thoracis, iv. 77, 82
Paraphimosis, iv. 197, 200
Paraplegia, iv. 157
Parotid gland, i. 5, 18, 54
2 k
-ocr page 288-
258 THE SURGICAL ANATOMY OF THE HORSE
Testicle, descent of, iv. 189
Thebesius :
foramina of, iv. 232
valve of, iv. 232
Thorax, iv. 62
Thrush, iv. 43
Thyro-arytenoid ligament, i. 65
-hyoid membrane, i. 64
Thyroid cartilage, i. 14, 63
Toe, iv. 1
Trachea, i. 14, 63 ; iv. 62
Tracheotomy, i. 69, 75
Tramp, iv. 21
Tread, iv. 21
Trephining, i. 99
Trichiasis, i. 117
Tricuspid valve, iv. 233
Trigonum vesica;, iv. 163
Tubercle of Lower, iv. 232
Tumours :
anal, iv. 139
on the sheath, iv. 196
rectal, iv. 139
vaginal, iv. 225
vesical, iv. 170
vulval, iv. 225
Tunica albuginea of penis, iv.
198
vaginalis, iv. 121, 183, 192
Umbilical orifice, iv. 118
Ureters, iv. 161
Urethra, iv. 163
Urethral fistula, iv. 171
sinus, iv. 198
stricture, iv. 171
tube, iv. 198
Urethrotomy, iv. 165
Urinary bladder, iv. 162
amputation of, iv. 17°
inversion of, iv. 168
prolapse, iv. 168
tumours, iv. 170
calculi, iv. 164
Urino-genital organs, iv. 160
Uterus, iv. 213
blood-supply, iv. 214
nerve-supply, iv. 214
Uvea, i. 120
Vagina, iv. 215
inversion of, iv. 223
occlusion of, iv. 226
Vaginal and vulval cysts and
tumours, iv. 225
Valsalva, sinus of, iv. 234
Varicocele, iv. 177
Vas deferens, iv. 173, 189
Rima glottidis, i. 13
Ringbone, iv. 59
Rivinius's ducts, i. 62
Rostrum, i. 16
Saddle galls, iv. 88
Salivary calculi, i. 59
fistula, i. 59
Sandcrack, iv. 28
Sarcocele, iv. 177
Schneiderian membrane, i. 11
Scirrhous cord, iv. 185
operation on, iv. 187
Sclerotic, i. 120
Scrotal sac, iv. 181
Scrotum, iv. 172, 180, 182, 183
Scutiform cartilage, i. 123
Section of head, i. 17
Seedy toe, iv. 25
Semilunar anastomosis, iv. 12, 18
crest, iv. 12
fibro-cartilages, iii. 96
sinus, iv. 13
valves, iv. 233
Sensitive frog, iv. 7, 9
laminae, iv. 8
sole, iv. 7
Septic peritonitis, iv. 183
Septum nasi, i. 10, 17
pectiniforme, iv. 198
Shear mouth, i. 34
Sheath, iv. 194, 195
injuries to, iv. 195
Shoulder abscess, iv. 84
slip, ii. 142
tumour, iv. 84
Sidebones, iv. 11, 50
Sigmoid cavity, ii. 50
Sinus of chest wall, iv. 98
of valsalva, iv. 234
venosus, iv. 232, 234
Sinuses :
frontal, i. 17, 96
inferior maxillary, i. 17, 97
sphenoidal, i. 98
superior maxillary, i. 17, 94
Sitfast, iv. 89
Small sesamoid bone, iv. 14
Smegma preputii, iv. 195
Soft palate, i. 9, 47
Solar plexus, iv. 8, 19
Sole, iv. 1, 2, 4
Sore shins, ii. 64
Spaying, iv. 208
Spermatic cord, iv. 173, 195
Spinal cord, iv. 153
Spleen, iv. 143
Splints, ii. 5, 59
Split tooth, i. 35
Sprains, ii. 129
Standing operation (castration),
iv. 178
Staphylotomy, i. 50
Stenosis of preputial orifice, iv.
196
Stenson's duct, i. 6, 58
Sternum, iv. 60
Stomach, iv. 127
Stringhalt, iii. 185
Stripping, iv. 34
Strongylus armatus, iv. 194
Sublingual gland, i. 62
Submaxillary gland, i. 4, 60
Suburethral notch, iv. 198
Supracarpal band, ii. 47
Supraorbital process, i. 2, 89
Suprarenal bodies, iv. 161
Synovial membrane, iv. 16
Tail, iv. 148
amputation of, iv. 152
Tarsal sheath, iii. 142
Teat, iv. 227
Teeth, i. 23
extraction, i. 39
repulsion, i. 39
Tendinous thoroughpin, iii. 143
Tendon sheaths, ii.
carpal, ii. 120
metacarpo- phalangeal,
»• '33
Tendons:
biceps, ii. 118
breakdown of, ii. 132
cunean, iii. 1 51
deep flexor of digit, iv. 17,
J2
diseases of:
flexor metatarsi, iii.
136
perforatus, iii. 141
tendo-Achilles, iii. 140
extensor pedis, iv. 16
flexor metatarsi, iii. 135
perforans, iv. 17, 52
infraspinatus, ii. 117
perforans, ii. 125, 129
perforatus, ii. 125, 129 ;
iii. 140
peroneal, iii. 154
tendo-Achilles, iii. 139
Tenotomy :
perforans, ii. 126
perforatus, iii. 127
supracarpal, ii. 123
Testicle, iv. 174, 180, 183, 192
-ocr page 289-
INDEX
259
Veins :
anterior gastric, iv. 242
mesenteric, iv. 242
tibia], iii. 210
axillary, ii. 181
azygos, iv. 240
brachial, ii. 26, 181
cartilaginous plexus, iv. 20
cephalic, iv. 68
circumflex, iv. 19
common iliac, iii. 211
coronary plexus, iv. 19,
20
digital, ii. 16, 25, 39,
178 ; iii. 18, 208 ; iv.
20
duodenal, iv. 242
external iliac, iii. 211
saphena, iii. 211
femoral, iii. 6, 211
hepatic, iv. 142, 242
intercostal, iv. 71
internal iliac, iii. 211
saphena, iii. 6, 210
subcutaneous of fore-
arm, ii. 36, 180
jugular, i. 75, 139
lateral plexus, iv. 20
Veins—continued
lumbar, iv. 241
median, ii. 36, 180
metacarpal, ii. 16, 25, 37,
179
metatarsal, iii. 6, 18, 26,
209
pampiniform plexus, iv. 173
pancreatic, iv. 242
peripheral, iv. 19
phrenic, iv. 242
podophyllous plexus, iv.
popliteal, iii. 29, 211
portal, iv. 142, 242
posterior auricular, i. 55
mesenteric, iv. 242
radial, ii. 26, 36, 181
tibial, iii. 2 10
vena cava, iv. 241
pulmonary, iv. 234
radial, ii. 180
renal, iv. 160, 241
solar plexus, iv. 19
spermatic, iv. 241
spur, iv. 67, 110
submaxillary, i. 44, 58
superior cervical, i. 20
Veins—continued
transverse facial, i. 56
ulnar, ii. 181
vertebral, i. 21
Velvety tissue, iv. 7
Ventricles, iv. 232
Ventricular systole, iv. 233
Vesico-genital pouch, iv. 215
Vesicula; seminales, iv. 174
Vestibular bulb, iv. 216
Vestibule, iv. 217
Villitis, iv. 23
Virborg's triangle, i. 78
Vocal cord, i. 14, 65
Vulva, iv. 215
occlusion of, iv. 226
Walker's cradle, i. 92
Wall, iv. 1
Wharton's duct, i. 4, 60
White line, iv. 2
Windgalls, ii. 108, 134
Withers, iv. 87
Wolf's teeth, i. 25, 29
Xiphoid cartilage, iv.
Zona tendinosa, iv. 232, 233
Bailliiri, Tindall & Cox, 8, Henrietta Street, Covent Garden London