the disease; even this may be accidentally or purposely hidden from
casual view by mud, ointments, tar, wax, putty, gutta-percha, or by the
long hairs of the coronet.
Sand cracks sometimes commence on the internal face of the wall,
involving its whole thickness excepting a thin layer on the outer
surface. In these cases the existence of the injury may be suspected
from a slight depression, which begins near the coronary band and
follows the direction of the horny fibers; but the trouble can only be
positively diagnosed by paring away the outside layers of horn until the
fissure is exposed. In toe cracks the walls of the fissure are in close
apposition when the foot receives the weight of the body, but when the
foot is raised from the ground the fissure opens. In quarter crack the
opposition is true; the fissure closes when the weight is removed from
the foot. As a rule, sand cracks begin at the coronary band, and as they
become older they not only extend downward, but they also grow deeper.
In old cases, particularly in toe cracks, the horn on the borders of the
fissure loses its vitality and scales off, sometimes through the greater
part of its thickness, leaving behind a rough and irregular channel
extending from the coronet to the end of the toe.
In many cases of quarter crack, and in some cases of toe crack as well,
if the edges remain close together, with but little motion, the fissure
is dry; but in other cases a thin, offensive discharge issues from the
crack and the ulcerated soft tissues, or a funguslike growth protrudes
from the narrow opening.
When the cracks are deep and the motion of their edges considerable, so
that the soft tissues are bruised and pinched with every movement, a
constant inflammation of the parts is maintained and the lameness is
severe.
Ordinarily the lameness of sand crack is slight when the patient walks,
but it is greatly aggravated when he is made to trot, and the harder the
road the worse he limps. Furthermore, the lameness is greater going
downhill than up, for the reason that these conditions are favorable to
an increased motion in the edges of the fissure. Lastly, more or less
hemorrhage accompanies the inception of a sand crack when the whole
thickness of the wall is involved. Subsequent hemorrhages may also take
place from fast work, jumping, or a misstep.
_Treatment._--So far as preventive measures are concerned, but little
can be done. The suppleness of the horn is to be maintained by the use
of ointments, damp floor, bedding, etc. The shoe is to be proportioned
to the weight and work of the animal; the nails holding it in place are
to be of proper size and not driven too near the heels; sufficient calks
and toe pieces must be added to the shoes of horses working on slippery
roads; also, the evils of jumping, fast driving, etc., are to be
avoided.
When a fissure has made its appearance, means are to be adopted which
will prevent it from growing longer or deeper; this can only be done by
arresting all motion in the edges. The best and simplest artificial
appliance for holding the borders of a toe crack together is the
Vachette clasp. These clasps and the instruments necessary for their
application can be had of any prominent maker of veterinary instruments.
(Pl. XXXVI.) These instruments comprise a cautery iron, with which two
notches are burned in the wall, one on each side of the crack, and
forceps with which the clasps are closed into place in the bottom of the
notches and the edges of the fissure brought close together. The clasps,
being made of stiff steel wire, are strong enough to prevent all motion
in the borders of the crack. Before these clasps are applied the fissure
should be thoroughly cleansed and dried, and if the injury is of recent
origin the crack may be filled with a putty made of 2 parts of
gutta-percha and 1 part of gum ammoniac. The number of clasps to be used
is to be determined by the length of the crack, the amount of motion to
be arrested, etc. Generally the clasps are from one-half to
three-quarters of an inch apart. The clasps answer equally as well in
quarter crack if the wall is sufficiently thick and not too dry and
brittle to withstand the strain.
In the absence of these instruments and clasps a hole may be drilled
through the horn across the fissure and the crack closed with a thin
nail made of tough iron, neatly clinched at both ends. A plate of steel
or brass is sometimes fitted to the parts and fastened on with short
screws; while this appliance may prevent much gaping of the fissure, it
does not entirely arrest motion of the edges, for the reason that the
plate and screw can not be rendered immobile.
If, for any reason, the measures above fail or can not be used, recourse
must be had to an operation. The horn is softened by the use of warm
baths and poultices, the patient cast, and the walls of the fissure
entirely removed with the knife. The horn removed is in the shape of the
letter V, with the base at the coronet. Care must be taken not to injure
the coronary band and the laminae. The wound is to be treated with mild
stimulant dressings, such as compound cresol solution, a weak solution
of carbolic acid, tincture of aloes, etc., oakum balls, and a roller
bandage. After a few days the wound will be covered with a new, white
horn, and only the oakum and bandages will be needed. As the new quarter
grows out, the lameness disappears, and the patient may be shod with a
bar shoe and returned to work.
In all cases of sand crack the growth of horn should be stimulated by
cauterizing the coronary band or by the use of blisters. In simple
quarter crack recovery will often take place if the coronet is
blistered, the foot shod with a "tip," and the patient turned to
pasture.
The shoe in toe crack should have a clip on each side of the fissure and
should be thicker at the toe than at the heels. The foot should be
lowered at the heels by paring, and spared at the toe, except directly
under the fissure, where it is to be pared away until it sets free from
the shoe.
When any of the complications referred to above arise, special measures
must be resorted to. For the proper treatment of gangrene of the lateral
cartilage and extensor tendon and caries of the coffin bone reference
may be had to the articles on quittors. If the horny tumor, known as
keraphyllocele, should develop, it is to be removed by the use of the
knife. Since this tumor develops on the inside of the horny box and may
involve other important organs of the foot in disease, its removal
should only be undertaken by a skillful surgeon.
NAVICULAR DISEASE.
Navicular disease is an inflammation of the sesamoid sheath, induced by
repeated bruising or laceration, and complicated in many cases by
inflammation and caries of the navicular bone. In some instances the
disease undoubtedly begins in the bone, and the sesamoid sheath becomes
involved subsequently by an extension of the inflammatory process.
(Plate XXXIV, fig. 5.)
The Thoroughbred horse is more commonly affected than any other, yet no
class or breed of horses is entirely exempt. The mule, however, seems
rarely, if ever, to suffer from it. For reasons which will appear when
considering the causes of the disease, the hind feet are not liable to
be affected. Usually but one fore foot suffers from the disease, but if
both should be attacked the trouble has become chronic in the first
before the second shows signs of the disease.
_Causes._--To comprehend fully how navicular disease may be caused by
conditions and usages common to nearly all animals, it is necessary to
recall the peculiar anatomy of the parts involved in the process and the
functions which they perform in locomotion.
It must be remembered that the fore legs largely support the weight of
the body when the animal is at rest, and that the faster he moves the
greater is the shock which the fore feet must receive as the body is
thrown forward by the propelling force of the hind legs. This shock
could not be withstood by the tissues of the fore feet and legs were it
not that it is largely dissipated by the elastic muscles which bind the
shoulder to the body, the ease with which the arm closes on the shoulder
blade, and the spring of the fetlock joint. Even these means, however,
are not sufficient within themselves to protect the foot from injury; so
nature has further supplemented them by placing the coffin joint on the
hind part of the coffin bone instead of directly on top of it, whereby a
large part of the shock of locomotion is dispersed before it can reach
the vertical column represented by the cannon, knee, and arm bones. A
still further provision is made by placing a soft, elastic pad--the frog
and plantar cushion--at the heels to receive the sesamoid expansion of
the flexor tendon as it is forced downward by the pressure of the
coronet bone against the navicular. Extraordinary as these means may
appear for the destruction of shock, and ample as they are when the
animal is at a slow pace or unweighted by rider or load, they fail to
relieve the parts completely from concussion and excessive pressure
whenever the opposite conditions are present. The result, then, is that
the coronet bone forces the navicular hard against the flexor tendon,
which, in turn, presses firmly against the navicular as the force of the
contracting muscles lifts the tendon into place. It is self-evident,
then, that the more rapid the pace and the greater the load, the greater
must these contending forces be, and the greater the liability to
injury. For the same reason horses with excessive knee action are more
liable to suffer from this disease than others, concussion of the foot
and intense pressure on the tendon being common among such horses.
Besides the above-mentioned exciting causes must be considered those
which predispose to the disease. Most prominent among these is heredity.
It may be claimed, however, that an inherited predisposition to
navicular disease consists not so much in a special susceptibility of
the tissues which are involved in the process as in a vice of
conformation which, as is well known, is liable to be transmitted from
parent to offspring. The faults of conformation most likely to be
followed by the development of navicular disease are an insufficient
plantar cushion, a small frog, high heels, excessive knee action, and
contracted heels. Finally, the environments of domestication and use,
such as dry stables, heavy pulling, bad shoeing, punctured wounds, etc.,
all have their influence in developing this disease.
_Symptoms._--In the early stages of navicular disease the symptoms are
generally very obscure. When the disease begins in inflammation of the
navicular bone, the animal while at rest points the affected foot a
time before any lameness is seen. While at work he apparently travels as
well as ever, but when placed in the stable one foot is set out in front
of the other, resting on the toe, with fetlock and knee flexed. After a
time, if the case is closely watched, the animal takes a few lame steps
while at work, but the lameness disappears as suddenly as it came, and
the driver doubts whether the animal was really lame at all. Later the
patient has a lame spell which may last during a greater part of the
day, but the next morning it is gone; he leaves the stable all right,
but goes lame again during the day. In times he has a severe attack of
lameness, which may last for a week or more, when a remission takes
place and it may be weeks or months before another attack supervenes.
Finally, he becomes constantly lame, and the more he is used the greater
the lameness.
In the lameness from navicular disease the affected leg always takes a
short step, and the toe of the foot first strikes the ground; so the
shoe is most worn at this point. If the patient is made to move
backward, the foot is set down with exceeding great care, and the weight
rests upon the affected leg but a moment. When exercised he often
stumbles, and if the road is rough he may fall on his knees. If he is
lame in both feet the gait is stilty, the shoulders seem stiff, and, if
made to work, he sweats profusely from intense pain. Early in the
development of the disease a careful examination will reveal some
increased heat in the heels and frog, particularly after work; as the
disease progresses this becomes more marked, until the whole foot is hot
to the touch. At the same time there is an increased sensibility of the
foot, for the patient flinches from the percussion of a hammer lightly
applied to the frog and heels or from the pressure of the smith's
pincers. The frog is generally shrunken, often of a pale-red color, and
at times is affected with thrush. If the heels are pared away so that
all the weight is received on the frog, or if the same result is
attained by the application of a bar shoe, the animal is excessively
lame. The muscles of the leg and shoulder shrink away and often tremble
as the animal stands at rest. After months of lameness the foot is found
to be shrunken in its diameter and apparently lengthened; the horn is
dry and brittle and has lost its natural gloss, while circular ridges,
developed most toward the heels, cover the upper part of the hoof. When
both feet are affected the animal points first one foot then the other,
and stands with the hind feet well forward beneath the body, so as to
relieve the fore feet as much as possible from bearing weight. In old
cases the wasting of the muscles and the knuckling at the fetlock become
so great that the leg can not be straightened and locomotion can
scarcely be performed. The disease generally makes a steady progress
without inclining to recovery--the remission of symptoms in the earlier
stages should not be interpreted as evidence that the process has
terminated. The complications usually seen are ringbones, sidebones,
thrush, contracted heels, quartercracks, and fractures of the navicular,
coronet, and pastern bones.
_Treatment._--But few cases of navicular disease recover. In the early
stages the wall of the heels should be rasped away, as directed in the
treatment for contracted heels, until the horn is quite thin; the
coronet should be well blistered with Spanish-fly ointment, and the
patient turned to grass in a damp field or meadow. After three or four
weeks the blister should be repeated. This treatment is to be continued
for two or three months. Plane shoes are to be put on when the patient
is returned to work. In chronic cases the animal should be put to slow,
easy work. To relieve the pain, neurotomy may be performed--an operation
in which the sense of feeling is destroyed in the foot by cutting out
pieces of the nerve at the fetlock. This operation in nowise cures the
disease, and, since it may be attended with serious results, can be
advised only in certain favorable cases, to be determined by the
veterinarian.
SIDEBONES.
A sidebone consists in a transformation of the lateral cartilages found
on the wings of the coffin bone into bony matter by the deposition of
lime salts. The disease is a common one, especially in heavy horses used
for draft, in cavalry horses, cow ponies, and other saddle horses, and
in runners and trotters.
Sidebones are peculiar to the fore feet, yet they occasionally develop
in the hind feet, where they are of little importance since they cause
no lameness. In many instances sidebones are of slow growth and, being
unaccompanied with acute inflammation, they cause no lameness until such
time as, by reason of their size, they interfere with the action of the
joint. (Plate XXXIV, fig. 4.)
_Causes._--Sidebones often grow in heavy horses without any apparent
injury, and their development has been attributed to the over-expansion
of the cartilages caused by the great weight of the animal. Blows and
other injuries to the cartilages may set up an inflammatory process
which ends in the formation of these bony growths. High-heeled shoes,
high calks, and long feet are always classed among the conditions which
may excite the growth of sidebones. They are often seen in connection
with contracted heels, ringbones, navicular disease, punctured wounds of
the foot, quarter cracks, and occasionally as a sequel to founder.
_Symptoms._--In the earlier stages of the disease, if inflammation is
present, the only evidence of the trouble to be detected is a little
fever over the seat of the affected cartilage and a slight lameness. In
the lameness of sidebones the toe of the foot first strikes the ground
and the step is shorter than natural. The subject comes out of the
stable stiff and sore, but the gait is more free after exercise.
Since the deposit of bony matter often begins in that part of the
cartilage where it is attached to the coffin bone, the diseased process
may exist for some time before the bony growth can be seen or felt.
Later, however, the cartilage can be felt to have lost its elastic
character, and by standing in front of the animal a prominence of the
coronary region at the quarters can be seen. Occasionally these bones
become so large as to bulge the hoof outward, and by pressing on the
joint they so interfere with locomotion that the animal becomes entirely
useless.
_Treatment._--So soon as the disease can be diagnosed active treatment
should be adopted. Cold-water bandages are to be used for a few days to
relieve the fever and soreness.
The improvement consequent on the use of these simple measures often
leads to the belief that the disease has recovered; but with a return to
work the lameness, fever, etc., reappears. For this reason the use of
blisters, or, better still, the firing iron, should follow on the
discontinuance of the cold bandages.
But in many instances no treatment will arrest the growth of these bony
tumors, and as a palliative measure neurotomy must be resorted to.
Generally this operation will so relieve the pain of locomotion that the
patient may be used for slow work; but in animals used for fast driving
or for saddle purposes, the operation is practically useless. Some years
ago at Fort Leavenworth I unnerved a number of cavalry horses that were
suffering from sidebones, and the records show that in less than seven
months all were more lame than ever. Since a predisposition to develop
sidebones may be inherited, animals suffering from this disease should
not be used for breeding purposes unless the trouble is known to have
originated from an accident.
RINGBONE.
A ringbone is the growth of a bony tumor on the ankle. This tumor is, in
fact, not the disease, but simply the result of an inflammatory action
set up in the periosteum and bone tissue proper of the pastern bones.
(Plate XXXIV, fig. 1.) (See also p. 313.)
_Causes._--Injuries, such as blows, sprains, overwork in young,
undeveloped animals, fast work on hard roads, jumping, etc., are among
the principal exciting causes of ringbone. Horses most disposed to this
disease are those with short, upright pasterns, for the reason that the
shock of locomotion is but imperfectly dissipated in the fore legs of
these animals. Improper shoeing, such as the use of high calks, a too
great shortening of the toe and correspondingly high heels, predispose
to this disease by increasing the concussion to the feet.
_Symptoms._--The first symptom of an actively developed ringbone is the
appearance of a lameness more or less acute. If the bony tumor forms on
the side or upper parts of the large pastern, its growth is generally
unattended with acute inflammatory action, and consequently produces no
lameness or evident fever. These are called "false" ringbones. But when
the tumors form on the whole circumference of the ankle, or simply in
front under the extensor tendon, or behind under the flexor tendons, or
if they involve the joints between the two pastern bones, or between the
small pastern and the coffin bone, the lameness is always severe. These
constitute the true ringbone. Besides lameness, the ankle of the
affected limb presents more or less heat, and in many instances a rather
firm, though limited, swelling of the deeper tissues over the seat of
the inflammatory process. The lameness of ringbone is characteristic in
that the heel is first placed on the ground when the disease is in a
fore leg, and the ankle is kept as rigid as possible. In the hind leg,
however, the toe strikes the ground first, when the ringbone is high on
the ankle, just as in health, but the ankle is maintained in a rigid
position. If the bony growth is under the front tendon of the hind leg,
or if it involves the coffin joint, the heel is brought to the ground
first. In the early stages of the disease it is not always easy to
diagnose ringbone, but when the deposits have reached some size they can
be felt and seen as well.
The importance of a ringbone depends on its seat and often on its size.
If it interferes with the joints or with the tendons it may cause an
incurable lameness, even though small. If it is on the sides of the
large pastern, the lameness generally disappears as soon as the tumor
has reached its growth and the inflammation subsides. Even when the
pastern joint is involved, if complete anchylosis results, the patient
may recover from the lameness with simply an imperfect action of the
foot remaining, due to the stiff joint.
_Treatment._--Before the bony growth has commenced the inflammatory
process may be cut short by the use of cold baths and wet bandages,
followed by one or more blisters. If the bony deposits have begun, the
firing iron should always be used. Even when the tumors are large and
the pastern joint involved, firing often hastens the process of
anchylosis and should always be tried.
When the lower joint is involved, or if the tumor interferes with the
action of the tendons, recovery is not to be expected. In many of these
latter cases, however, the animal may be made serviceable by proper
shoeing. If the patient walks with the toe on the ground, the foot
should be shod with a high-heeled shoe and a short toe. On the other
hand, if he walks on the heel, a thick-toed and thin-heeled shoe must be
worn.
Since ringbone is considered to be one of the hereditary diseases, no
animal suffering from this trouble should ever be used for breeding
purposes.
LAMINITIS, OR FOUNDER.
Laminitis is a simple inflammation of the sensitive laminae of the feet,
characterized by the general phenomena attending inflammation of the
skin and mucous membranes, producing no constitutional disturbances
except those dependent upon the local disease, and having a strong
tendency, in severe cases, to destructive disorganization of the tissues
affected.
_Causes._--The causes of laminitis are as wide and variable as in any of
the local inflammations, and may be divided into two classes--the
predisposing and the exciting.
_Predisposing causes._--From personal observation I do not know that any
particular construction of foot or any special breed of horses is
predisposed to this disease, neither can I find anything to warrant the
assumption that it is in any way hereditary; so that while we may easily
cultivate a predisposition to the disease, it does not originate without
an exciting cause. Like most other tissues, a predisposition to
inflammation may be induced in the sensitive laminae by any cause which
lessens their power of withstanding the work imposed on them. It exists
to an extent in those animals unaccustomed to work, particularly if they
are plethoric, and in all that have been previous subjects of the
disease, for the same rule holds good here that we find in so many
diseases--i. e., that one attack impairs the functional activity of the
affected tissues and renders them more easy of a subsequent
inflammation. Unusual excitement by determining an excessive blood
supply, bad shoeing, careless paring of the feet by removing the sole
support, and high calkings without corresponding toe pieces must be
included under this head.
_Exciting causes._--The exciting causes of laminitis are many and
varied. The most common are concussion, overexertion, exhaustion, rapid
changes of temperature, ingestion of certain feeds, purgatives, and the
oft-mentioned metastasis.