point in interfering, we may now consider the subject of the
predisposition which brings such serious results upon the suffering
animal, and the conditions which lead to and accompany it. These are
numerous, but the first in frequency and importance is peculiarity of
conformation in the animals addicted to it. The first class will include
horses, whose chests are narrow and whose legs do not stand straight and
upright, but are crooked and pigeon-toed in and out. The second class
includes those whose legs are weak, either from youth or hard labor, or
from severe attacks of sickness. Another class is made up of those
having abnormally developed feet, or which have been badly shod with
unnecessarily wide or heavy shoes. Another class consists of those that
are affected with swollen fetlocks or chronic, edematous swelling of the
leg. Another is formed of animals with a peculiar action, as those whose
knee action is very high, and it is these that furnish most of the cases
of speedy cut.
_Prognosis._--The prognosis of interfering is never a very serious one.
However violent the blow may be it is rarely that subsequent
complications of a troublesome nature occur. The principal evil
attending it is a liability to be followed by a thickened or callous
deposit which is not only an eyesore and a blemish, but constitutes a
new and increased predisposition. The remark that "an animal which has
interfered once is always liable to interfere," is often confirmed and
sanctioned by a recurrence of the trouble.
_Treatment._--Another point in which there is a resemblance between this
lesion and others which we have considered is in its responsiveness to
the same treatment with them. Indeed, the prescription of warm
fomentations, soothing applications, and astringent and resolvent
mixtures, in a majority of cases, is the first that occurs all through
the list. If the swelling assumes the character of a serous collection,
pressure, cold water, and bandages will contribute to its removal. If
suppuration seems to be established and the swelling assumes the
character of a developing abscess, hot poultices of flaxseed or of
boiled vegetables and the embrocations of sedative ointments, those of
basilicon, or vaseline, impregnated with preparations of opium or
belladonna--all these recommend themselves by their general adaptation
and the beneficial results which have followed their administration, not
less in one case than in another. When an abscess has formed and is
fluctuating, it should be carefully but fully opened to evacuate the
pus. If it is a serous cyst, some care is necessary in emptying it, and
the possibility of the extension of the inflammation to the joint must
be taken into consideration. When the cavities have been emptied and
have closed by filling up with granulations, or if, not being opened,
the contents have been reabsorbed, and there remains in either case a
plastic exudation and a tendency to the callous organization that may
yet exist, blisters under their various forms, including those of
cantharides, of mercury, and of iodin, are then indicated, principally
in the early stages, as it is then that their effects will prove most
satisfactory. The use of the actual cautery, with fine points,
penetrating deeply throughout the enlargement, has in our hands, when
used in the very early stages of its formation, nearly always brought on
a radical recovery with complete absorption of the thickening.
STRINGHALT.
This is an involuntary movement of one or both hind legs, in which the
foot is suddenly and spasmodically lifted from the ground much higher
than it is normally carried, with excessive flexion of one bone upon the
other. This peculiarity is usually prominent, although it may disappear
with work, only to reappear after a short rest. Sometimes it is most
apparent at a trot, sometimes at a walk, and other times only when
turned around; or it may not be affected by the gait of the horse. It
does not seem to be influenced by the horse's age, young and old being
alike affected. Its first manifestations are sometimes very slight. It
has been noticed as occurring in an animal when backing out of his
stable and ceasing immediately after. In some animals it is best seen
when the animal is turning around on the affected leg, and it is not
noticed when he moves straight forward. That this peculiar action
interferes with facility of locomotion and detracts from a horse's claim
to soundness can not for a moment be denied.
_Cause._--Veterinarians and pathologists are yet in doubt in respect to
the cause of this affection, as well as to its essential nature. Whether
it results from disease of the hock, of an ulcerative character; whether
it springs from a malformation; whether it is a shortening of the
ligaments, a chronic inflammation of the sciatic nerve, or a disease of
the spinal cord; whether it is purely a muscular or purely a nervous
lesion, or a compound of both--it still continues, if an etiologist is
bound to possess universal knowledge within the scope of his special
studies, to be his reproach and his puzzle.
_Treatment._--When there is a known or suspected cause the treatment
should be directed toward this factor. If due to local inflammation of
the hock or foot, only this local lesion should be treated. If it
remains after the local lesion has healed, or if we have no assignable
cause, the best results have followed the sectioning of the lateral
extensor of the foot. A competent veterinarian alone should undertake
this operation.
THROMBOSIS.
There are certain forms of lameness which are very peculiar in their
manifestation, and which to the nonprofessional mind must appear to
belong to the domain of mystery or theory instead of occupying a
well-established position among the subjects of equine pathology. Yet
they are no less susceptible of actual demonstration and of positive
comprehension than many facts which, plain and familiar to the general
understanding now, were once ranked among things occult and
unsearchable. A thrombus, considered as a cause of lameness, may find a
place among these understood mysteries.
_Cause._--Under certain peculiar conditions of inflammation of the blood
vessels, and also in aneurisms, clots of blood are sometimes formed in
the arteries and find their way in the general circulation. At first,
while very small, or sufficiently so to pass from one vessel to another,
they move from a small vessel to a larger, and from that to one still
larger, constantly increasing in size until at some given point, from
their inability to enter smaller vessels, their movement is finally
arrested. The artery is thus effectually dammed, and the clot in a short
time cuts off completely the supply of blood from the parts beyond. This
is thrombosis, and it often gives rise to sudden and excessive lameness
of a very painful character.
_Symptoms._--Thrombi may form in any of the arteries, and doubtless have
been the cause of many cases of lameness which could never be accounted
for. If they exist in small arteries their diagnosis will probably fail
to be made out with certainty, but when situated in the larger trunks a
strong suspicion of their presence may be excited. In some cases they
may even be recognized with positive accuracy, as when the vessels which
supply the posterior extremities are affected by the blocking up of the
posterior aorta or its ramifications.
The existence of thrombosis of the arteries of the hind leg may always
be suspected when the following history is known: The general health of
the animal is good, but symptoms of lameness in one of the legs have
been developed, becoming more marked as he is worked, and especially
when driven at a fast gait. But the disturbance is not permanent, and
the lameness disappears almost immediately after a rest. There is an
increase of the difficulty, however, and, though the animal may walk
normally, he will, when made to trot, very soon begin to slacken his
pace and to show signs of the trouble, and if urged to increase his
speed will become lamer and lamer; an abundant perspiration will break
out; he will refuse to go, and if forced he shows weakness behind, seems
ready to fall, and perhaps does fall. While on his feet the leg is kept
in constant motion, up and down, and is kept from the ground as if the
contact were too painful to bear. If undisturbed this series of symptoms
will gradually subside, sometimes very soon, and occasionally after a
few hours he will return to an apparently perfect condition. A return
to labor will lead to a renewal of the same incidents.
A history like this suggests a strong suspicion of a thrombus in an
artery of the hind leg, and this suspicion will be confirmed by the
external symptoms exhibited by the animal. The total absence of any
other disease which might account for the lameness, and a manifest
diminution of heat over a part or the whole of the extremity, when
compared with the opposite side or with any other portion of the body; a
sensation of cold attendant on the pain, but gradually subsiding as the
pain subsides, and the circulation, quickened by the rest, has been
reestablished throughout the extremity; all these are confirmatory
circumstances. Still, it is thus far only a suspicion, and absolute
certainty is yet wanting. To establish the truth of the case the rectal
exploration must be resorted to. The hands then, well prepared and
carefully introduced into the rectum, must explore for the truth, first
feeling for the large blood vessels which, divided at the aorta,
separate to supply the right and left legs. These must be compared in
respect to the pulsation and other particulars. The artery which is
healthy will, of course, exhibit all the proper conditions of that
state. On the other hand, if the vessel appears to the feel hard, more
or less cordy, and pulseless, or giving a sensation of fluttering, as of
a small volume of blood with a trickling motion passing through a
confined space, the difference between the sides will make the case
plain. The first will be the full flow of the circulation through an
unobstructed channel, the other a forced passage of the fluid between
the thrombus and the coats of the artery. In such case the prognosis is
necessarily a grave one and the disease is more liable to grow Worse
than better.
_Treatment._--No form of treatment can be advised; the suffering or a
helpless and useless animal can only be terminated by that which ends
all.
Cases occur, however, where this condition of the blood vessels exists
in a much less degree, and the diseased condition is not sufficiently
pronounced for final condemnation. There may even be a possibility of
the absorption of the clot, or that an increase of the collateral
circulation may be sufficient to supply the parts with blood. In such
cases spontaneous recovery may follow moderate exercise in the pasture,
field, or stable, or continuous light work may be given, but too much
hope should not be placed in such treatment.
SPRAINS OF THE LOINS.
This is an affection which suggests to the mind the idea of muscular
injury, and is difficult to distinguish from many similar cases. If the
animal shrinks from the slightest pressure or pinching of the spine in
the region of the loins, he is by many pronounced to be "lame in the
loins," or "sprained in the loins," or "weak in the kidneys." This is a
grave error, as in fact this simple and gentle yielding to such a
pressure is not a pathological sign, but is normal and significant of
health. Yet there are several conditions to which the definition of
"sprains of the loins" may apply which are not strictly normal.
_Cause._--The muscles of the back and those of the loins proper, as the
psoas, may have been injured, or again there may be trouble of a
rheumatic nature, perhaps suggestive of lumbago. Diseases of the bones
of the vertebral column, or even those of the organs of circulation, may
give rise to an exhibition of similar symptoms.
_Symptoms._--The symptoms are characteristic of a loss of rigidity or
firmness of the vertebral column, both when the animal is at rest and in
action. In the former condition, or when at rest, there is an arched
condition of the back and a constrained posture in standing, with the
hind legs separated. In the latter there is a lateral, balancing
movement at the loins, principally noticeable while the animal is in the
act of trotting--a peculiar motion, sometimes referred to as a "crick in
the back," or what the French call a "tour de bateau." If, while in
action, the animal is suddenly made to halt, the act is accompanied with
much pain, the back suddenly arching or bending laterally, and perhaps
the hind legs thrown under the body, as if unable to perform their
functions in stopping, and sometimes it is only accomplished at the cost
of a sudden and severe fall. This manifestation is also exhibited when
the animal is called upon to back, when a repetition of the same
symptoms will also occur.
If a slight pressure on the back or the loins is followed by a moderate
yielding of the animal, it is, as before remarked, a good sign of
health. With a sprain of the loins pressure of any kind is painful, and
will cause the animal to bend or to crouch under it more or less,
according to the weight of the pressure. Heavy loads, and even heavy
harnessing, will develop this tenderness. In lying down he seems to
suffer much discomfort, and often accompanies the act with groaning, and
when compelled to rise does so only with great difficulty and seldom
succeeds without repeated efforts.
Sprains of muscles proper, when recent, will always be accompanied with
this series of symptoms, and the fact of their exhibition, with an
excessive sensibility of the parts, and possibly with a degree of
swelling, will always justify a diagnosis of acute muscular lesion, and
especially so if accompanied with a history of violent efforts, powerful
muscular strains, falls, heavy loading, etc., connected with the case.
If the symptoms have been of slow development and gradual increase, it
becomes a more difficult task to determine whether the diagnosis points
to pathological changes in the structure of the muscles or of the bones,
the nervous centers, or the blood vessels of the region. And yet it is
important to decide as to which particular structure is affected in
reference to the question of prognosis, as the degree of gravity of the
lesion will depend largely upon whether the disabled condition of the
animal is due to an acute or a chronic disease.
_Treatment._--The prescription which will necessarily first of all
suggest itself for sprains of the loins is rest. An animal so affected
should be immediately placed in slings, and none of his efforts to
release himself should be allowed to succeed. Hot compresses, cold-water
douches, sweating applications, stimulating frictions, strengthening
charges, blistering ointments of cantharides and the actual cautery, all
have their advocates, but in no case can the immobility obtained by the
slings be dispensed with. In many cases in which the weakness of the
hind quarters was caused by disease of the nervous centers electricity
has also yielded good results.
FOOTNOTES:
[2] This bandage consists of a cloth drenched in warm water or a
dripping bandage laid around the diseased part, then covered by several
layers of woolen blanket or cloth, which is in turn covered by parchment
paper, rubber cloth, or other impervious material. Heat, moisture, and
pressure are obtained by such a bandage if water is poured upon it
several times daily.
DISEASES OF THE FETLOCK, ANKLE, AND FOOT.
By A. A. HOLCOMBE, D. V. S.,
_Veterinary Inspector, Bureau of Animal Industry._
ANATOMICAL REVIEW OF THE FOOT.
In a description of the foot of the horse it is customary to include
only the hoof and its contents, yet, from a zoological standpoint, the
foot includes all the leg from the knee and the hock down.
The foot of the horse is undoubtedly the most important part of the
animal, so far as veterinary surgery is concerned, for the reason that
it is subject to so many injuries and diseases which in part or in whole
render the patient unfit for the labor demanded of him. The old aphorism
"no foot no horse" is as true to-day as when first expressed; in fact,
domestication, coupled with the multiplied uses to which the animal is
put, and the constant reproduction of hereditary defects and tendencies,
has largely transformed the ancient "companion of the wind" into a very
common piece of machinery which is often out of repair, and at best is
but shortlived in its usefulness.
Since the value of the horse depends largely or even entirely upon his
ability to labor, it is essential that his organs of locomotion be kept
sound. To accomplish this end it is necessary not only to know how to
cure all diseases to which these organs are liable but, better still,
how to prevent them.
An important prerequisite to the detection and cure of disease is a
knowledge of the construction and function of the parts which may be
involved in the diseased process. Hence, first of all, the anatomical
structures must be understood. (See also p. 583.)
The bones of the fetlock and foot constitute the skeleton on which the
other structures are built and comprise the lower end of the cannon bone
(the metacarpus in the fore leg, the metatarsus in the hind leg), the
two sesamoids, the large pastern or os suffraginis, the small pastern or
coronet, the small sesamoid or navicular bone, and the coffin bone or os
pedis. (Plate XXXIV, fig. 3.)
The cannon bone extends from the knee or hock to the fetlock, is
cylindrical in shape, and stands nearly or quite perpendicular.
The sesamoids occur in pairs, are small, shaped like a three-faced
pyramid, and are set behind the fetlock joint, at the upper end of the
large pastern, with the base of the pyramid down.
The large pastern is a very compact bone, set in an oblique direction
downward and forward, and extends from the cannon bone to the coronet.
The coronet is a short, cube-shaped bone, set between the large pastern
and coffin bone, in the same oblique direction.
The navicular bone is short, flattened above and below, and is attached
to the coffin bone behind.
The coffin bone forms the end of the foot and is shaped like the horny
box in which it is inclosed.
All these bones are covered on the surfaces which go to make up the
joints with a cartilage of incrustation, while the portions between are
covered with a fibrous membrane called the periosteum.
The joints of the legs are of especial importance, since any
interference with their function very largely impairs the value of the
animal for most purposes. As the joints of the foot and ankle are at the
point of greatest concussion they are the ones most subject to injury
and disease.
There are three of these joints--the fetlock, pastern, and coffin. They
are made by the union of two or more bones, held together by ligaments
of fibrous tissue, and are lubricated by a thick, viscid fluid, called
synovia, which is secreted by a special membrane inclosing the joints.
The fetlock joint is made by the union of the lower end of the cannon
and the upper end of the large pastern bones, supplemented by the two
sesamoids, so placed behind the upper end of the pastern that the joint
is capable of a very extensive motion. These bones are held together by
ligaments, only one of which--the suspensory--demands special mention.
The suspensory ligament of the fetlock starts from the knee, extends
down behind the cannon, lying behind the two splint bones, until near
the fetlock, where it divides and sends a branch on each side of the
joint, downward and forward, to become attached on the sides of the
extensor tendon at the lower end of the pastern bone. As it crosses the
sesamoids, on the posterior borders of the fetlock, it throws out fibers
which hold it fast to these bones. (Plate XXXIV, fig. 2.)
The pastern joint is made by the union of the two pastern bones.
The coffin joint is made by the union of the small pastern, coffin, and
small sesamoid, or navicular bones, the latter being set behind and
beneath the joint surface of the coffin bone in such way as to receive
largely the weight of the small pastern.
Three tendons serve to move the bones of the foot one on another. Two of
these flex, or bend, the joints, while the other extends, or
straightens, the column of bones. (Plate XXXIII, fig. 5.)
The flexor pedis perforans, or deep flexor of the foot, passes down
behind the cannon bone, lying against the suspensory ligament in front,
crosses the fetlock joint in the groove made by the union of the two
sesamoids, and is attached to the bottom on the coffin bone, after
covering the navicular, by a wide expansion of its fibers. It is the
function of this tendon to flex the coffin bone and, with it, the horny
box.
The flexor pedis perforatus, or superficial flexor of the foot, follows
the course of the preceding tendon and is attached to the middle of the
ankle. The function of this tendon is to flex the foot at the fetlock.
The extensor pedis runs down in front of the leg, is attached on the
most prominent point of the coffin bone, and has for function the
straightening of the bones of the ankle and foot.
The bones, ligaments, and tendons are covered by a loose connective
tissue, which gives a symmetry to the parts by filling up and rounding
off, and all are protected by the skin and hoof.
The skin of the fetlock and ankle is generally characterized by its
thickness and the length of its hairs, especially around the hind parts
of the fetlock joint in certain breeds of horses. The most important
part of this envelope is that known as the coronary band.
The coronary band is that portion of the skin which secretes the horn of
which the wall of the hoof is made. This horn much resembles the nail
which grows on the fingers and toes of man. It is composed of
cylindrical tubes, which are held together by a tenacious, opaque
matter. The horn extends from the coronary band to the lower border of
the hoof. (Plate XXXII, fig. 1.)
The hoof is a box of horn, consisting of a wall, sole, and frog, and
contains, besides the coffin, navicular, and part of the small pastern
bones, the sensitive laminae, plantar cushion, and the lateral
cartilages. (Plate XXXIII, fig. 4.)
The sole of the foot incloses the box on the ground surface, is shaped
like the circumference of the foot, except that a V-shaped opening is
left behind for the reception of the frog, and is concave on the lower
surface. The sole is produced by the velvety tissue, a thin membrane
covering the plantar cushion and other soft tissues beneath the coffin
bone. The horn of the sole differs from the horn of the wall in that its
tubes are not straight and from the fact that it scales off in pieces
over the whole surface.
The frog is a triangular-shaped body, divided into two equal parts by a
deep fissure, extending from its apex in front to the base. It fills the
triangular space in the sole, to which it is intimately attached by its
borders. The horn of the frog is produced in the same manner as the
sole; but it differs from both the wall and sole in that the horn is
soft, moist, and elastic to a remarkable degree. It is the function of
the frog to destroy shock and to prevent slipping.
The sensitive laminae are thin plates of soft tissue covering the entire
anterior surface of the coffin bone. They are present in great numbers,
and by fitting into corresponding grooves on the inner surface of the
horn of the wall the union of the soft and horny tissues is made
complete. (Plate XXXII, fig. 1.)
The plantar cushion is a thick pad of fibrous tissue placed behind and
under the navicular and coffin bones and resting on the sole and frog,
for the purpose of receiving the downward pressure of the column of
bones and to destroy shock. (Plate XXXII, fig. 4.)
The lateral cartilages are attached, one on each side, to the wings of
the coffin bone by their inferior borders. They are thin plates of
fibro-cartilage, and their function is to assist the frog and adjacent
structures to regain their proper position after having been displaced
by the weight of the body while the foot rested on the ground. (Plate
XXXII, fig. 2.)
FAULTS OF CONFORMATION.
A large percentage of horses have feet which are not perfect in
conformation, and as a consequence they are especially predisposed to
certain injuries and diseases.
_Flatfoot_ is that condition in which the sole has little or no
convexity. It is a peculiarity common to some breeds, especially heavy,
lymphatic animals raised on low, marshy soils. It is confined to the
fore feet, which are generally broad, low-heeled, and with a wall less
upright than is seen in the perfect foot.