DISEASES OF THE FOOT
GENERAL DISCUSSION.--The foot of the horse as generally spoken of, includes
the hoof and the structures that are enclosed by it (Fig. 36). It may be
divided into three parts, the insensitive and sensitive structures and the
bony core. The _insensitive foot_ or _hoof_ is divided into wall, sole,
frog and bars. The _sensitive foot_ is divided into vascular tissue and
elastic apparatus. The vascular tissue is in turn divided into coronary
cushion, laminae and velvety tissue. The elastic apparatus is divided into
plantar cushion and fibro-cartilages. The _bony core_ is formed by the
navicular and third digital bones. The hoof and vascular tissue in turn
enclose the elastic apparatus and bony core.
[Illustration: FIG. 36.--Photograph of a model of the foot: wall; sensitive
tissue; plantar cushion, inferior dark portion, sole and frog; lateral
cartilage; and pedal bone.]
THE WALL forms that portion of the hoof seen when the foot rests on the
ground (Fig. 37). It is covered by a thin layer of horny tissue, the
_peripole,_ that coats over the wall and assists in preventing its drying
out. On lifting the foot and examining its inferior surface, it is noticed
that the wall at the heels is inflected under the foot and in a forward
direction. This portion of the wall is termed the _bars._ Within the
bearing margin of the wall and in front of the bars is a thick, concave,
horny plate that forms the _sole._ At the heels and between the bars is a
wedge-shaped mass of rather soft horny tissue that projects forward into
the sole. This is the _foot pad_ or _horny frog._ It is divided into two
lateral portions by a medium cleft.
THE CORONARY CUSHION projects into the upper border of the wall. It is
covered with vascular papillae which secrete the horny fibres that form the
wall. The _vascular laminae_ are leaf-like projections, the sides of which
are covered by secondary leaves. _Horny laminae_, arranged the same as
vascular laminae, line the wall. These two structures are so firmly united
that it is impossible to tear them apart without destroying the tissue. The
_velvety tissue_ covers all of the inferior surface of the foot, with the
exception of the bars. As the name indicates, its surface is covered by
vascular papillae that resemble the ply on velvet. It is firmly united to
the horny sole which it secretes.
[Illustration: FIG. 37.--Foot showing neglect in trimming wall.]
The lateral cartilages are attached to the posterior angles of the pedal
bone. They are flattened from side to side, and the portion that projects
above the coronary cushion may be felt by pressing on the skin that covers
it. The _plantar cushion_ is a wedge-shaped piece of tissue formed by
interlacing connective-tissue fibres and fat. It is limited on each side by
the lateral cartilages. Its inferior face is moulded to the frog.
THE BONY CORE formed by the last bone of the digit and the coffin bone was
described briefly with the other foot bones. A very important bursa,
because it is so frequently inflamed in coffin-joint lameness, facilitates
the gliding of the flexor tendon over the navicular bone before it becomes
attached to the inferior face of the pedal or digital bone.
SIDE-BONES.--This is a chronic inflammation of the lateral cartilages of
the foot that results in their ossification (Fig. 38). This unsoundness is
common in heavy horses, especially if worked on city streets. The
inflammation affects the cartilages of the front feet, rarely those of the
hindfeet.
_The hereditary tendency_ toward the development of side-bones is an
important predisposing factor. It is not uncommon to meet with this
unsoundness in young horses that have never been worked. Low, weak heels,
flat, spreading feet, or any other faulty conformation of the foot are
predisposing factors.
[Illustration: FIG. 38.--A very large side bone.]
The character of the work is an important _exciting cause._ Continuous work
over paved streets, especially if the horse is shod with high-heeled shoes,
increases the shock received by the elastic apparatus of the foot. This
produces more or less irritation to the lateral cartilages, which may
result in their complete ossification. Punctured wounds in the regions of
the cartilage may cause it to become inflamed and changed to bone.
The following _symptoms_ may be noted. Farm horses that have side-bones
seldom show lameness. This is because they are worked on soft ground and
not on a hard street or road. Driving and dray horses may step short with
the front feet, or show a stilty action. This may disappear with exercise.
The lameness is sometimes marked. The local diseased changes are the
greatest help in the recognition of side-bones. Horses should not be passed
as sound without making a careful examination of the lateral cartilages.
This examination is made by pressure over the region of the cartilage with
the thumb or fingers. This is for the purpose of testing its elasticity. If
it feels rigid and rough, the cartilaginous tissue has been replaced by
bony tissue, and the animal should be classed as unsound.
_The treatment_ is largely preventive. Horses with side-bones should not be
bred. It is not advisable to use horses with side-bones on the road or city
streets. Shoeing with rubber pads may help in overcoming the concussion and
relieve the lameness. Sectioning the sensory nerves going to this portion
of the foot is advisable in driving horses. Rest and counterirritation
relieve the lameness for a short time.
NAVICULAR DISEASE.--In navicular disease the bursa, flexor tendon, and
navicular bone may become chronically inflamed. Because of the seat of the
lameness, it is commonly known as "coffin-joint" lameness. This disease
affects standard and thoroughbred horses more often than it does the
coarser breeds. One or both front feet may be affected (Fig. 39).
_Hereditary causes_ are largely responsible for navicular disease. The
tendency toward this disease probably depends on such peculiarities of
conformation as narrow, weak, high heels, long pasterns and too long a toe.
The character of the work is an important factor. Hurried, rapid movements
throw considerable strain on the navicular region, increasing the danger
from injury. This is, no doubt, one reason for "coffin-joint" lameness
being more common in driving and speed horses than in slow-going work
animals. Rheumatic inflammation, bad shoeing and punctured wounds in the
region of the bursa many cause it.
[Illustration: FIG. 39.--A case of navicular disease involving one front
foot. The diseased foot is the smaller.]
The _first symptom_ usually noted is a tendency to stumble. When standing
in the stable, the animal "points" or rests the diseased foot. Sometimes it
rests the heel of the lame foot on the wall of the opposite foot. If both
feet are affected, the animal may rest them alternately, or take a position
with both feet well in front of the normal position. The inflamed
structures are so covered by other tissues that it is difficult to detect
the local inflammation, or cause the animal to flinch by applying pressure
over the region. As the disease becomes more advanced, the lameness becomes
permanent. The limb is carried forward stiffly and rapidly and the animal
stumbles when travelling over rough ground. In time, because of the little
weight thrown on the posterior portion of the foot, the quarters may become
higher, contracted and more upright and the frog smaller. If one foot is
diseased, it becomes smaller than the opposite foot.
The following _preventive measures_ may be recommended. We should not use
animals having faulty conformation of the feet for breeding, because the
offspring of such individuals have an inherent tendency toward navicular
and other foot diseases. Animals that have "coffin-joint" lameness should
be allowed to run in pasture as much as possible, because natural
conditions help to keep down the inflammation and soreness and promote a
more healthy condition of the foot. In shoeing the horse it is best to
shorten the toe and raise the heel. It is advisable in the more favorable
cases to cut the sensory nerves of the foot. This operation destroys the
sensation in the foot, and should not be performed on feet with weak heels,
or that are wide or spreading.
[Illustration: FIG. 40.--An improperly shod foot; note the manner in which
the wall is cut away at the toe.]
CONTRACTED QUARTERS.--This condition of the feet is characterized by the
foot becoming narrow in its posterior portion. One or both of the quarters
may be affected. It is principally observed in the forefeet.
The _causes_ of contraction of the foot may be classed as _predisposing_,
_secondary_ and _exciting_. It may accompany chronic diseases of the foot,
such as navicular disease and side-bones. Weak heels is the principal
predisposing factor. Any condition that tends to prevent the hoof from
taking up moisture, or causes it to lose moisture, may cause the horn to
lose flexibility and contract. This is one of the reasons why horses that
are worked continuously in cities, or used for driving, frequently develop
contracted feet. Ill-fitting shoes, excessive rasping of the wall and bars,
and allowing the shoes to stay on the foot for too long a time are
responsible to a very large degree for this disorder of the foot (Fig. 40).
The following _local symptoms_ may occur: The wall of the foot at the
quarters may appear drawn in at its superior or inferior portion. Sometimes
one or both quarters are perpendicular, or nearly so. The foot then appears
too narrow at the heel, too elongated and less rounded than normal. The
changes in the appearance of the inferior surface of the hoof vary. The
changes here may be so slight that they are not noticed. In well advanced
and neglected cases the arch of the sole is increased, the frog is narrow
and atrophied and the bars high and perpendicular. Corns may accompany the
contraction. The foot may feel feverish. The animal may manifest the pain
in the feet when standing at rest by pointing and changing their position.
When lameness is present, it may resemble that occurring in inflammation of
lateral cartilages and navicular disease.
_Preventive treatment_ is of the greatest importance. This consists in
giving the feet an opportunity to take up moisture when they are exposed to
abnormal conditions and become feverish. Under such conditions, it is
advisable to occasionally remove the shoes and turn the animal into a
pasture or lot. It is best to do this in the fall or winter when the ground
is wet. If this can not be practised, the shoes should be removed and a
poultice of ground flaxseed and bran, equal parts, applied to the feet for
a period of eight or ten hours, daily for a week or two. A plank trough six
inches deep, two feet wide and as long as the stall is wide may be filled
with a stiff clay, and the horse made to stand with its front feet in the
clay bath for ten or twelve hours daily. When grooming the horse, the foot
should be cleaned with a foot-hook and washed with clean water. Hoof
ointments should be avoided so far as possible. The importance of fitting
the shoe to the foot, avoiding the too free use of the rasp and hoof knife
and resetting or changing the shoe when necessary can not be overestimated.
Shoeing the animal with a special shoe is sometimes necessary. It is not
advisable to attempt the forcible expansion of the quarters. Lowering the
heels by careful trimming of the wall and sole and permitting frog pressure
may be all the special attention required.
SAND-CRACK.--A fissure in the wall of the foot running in the same
direction as the horny fibres, or a seam in the wall resulting from the
healing of the fissure is termed sand-crack. The position and extent of the
fissure or seam vary. It may involve the wall of the _toe_ (toe-crack)
(Fig. 41) or _quarter_ (quarter-crack) (Fig. 42). It is _superficial_ or
_deep_, according to the thickness of the wall involved; _complete_ or
_incomplete_, depending on whether it extends from the bearing margin of
the wall to the coronary band or only a portion of the distance; _simple_,
when the horny tissue only is involved; and _complicated_, when the
sensitive tissue beneath becomes injured and inflamed. Cracks of long
standing usually have thick, rough margins.
_The causes_ of this unsoundness are poor quality of horn, improper care
and injuries. Sand-cracks commonly occur in hoofs that are dry and brittle
and have thin walls. In young horses incomplete cracks due to the wall
becoming long and breaking off in large pieces are common. Unequal
distribution of weight, the result of unskilled shoeing, or any other
condition that may cause the foot to become unbalanced, using the foot rasp
too freely, and such diseases as quittor, corns and contracted quarters
subject the animal to this form of unsoundness. Any injury to the coronary
cushion that secretes the fibres of the horny wall may result in either
toe- or quarter-crack. Treads and barb-wire cuts are common injuries to the
region of the coronet.
_The preventive treatment_ consists in preserving a healthy condition of
the horn by giving the foot the necessary care and attention in the way of
proper trimming and shoeing, and providing it with the necessary moisture
by means of foot-baths, wet clay and poultices. Quarter-cracks respond to
treatment more quickly than toe-cracks. The treatment is practically the
same for both. This consists in preventing motion in the margins of the
fissure so far as possible.
[Illustration: FIG. 41.--Toe-cracks.]
[Illustration: FIG. 42.--Quarter-crack caused by barb-wire cut.]
_The treatment for fissures_ in the region of the toe and quarter is as
follows: The wall should be cut away along the margins of the crack until
it is quite thin; and extra nail holes should be made in the shoe, and a
nail driven into the bearing margin of the wall a little to each side of
the fissure. The wall at the toe should be shortened and the toe of the
shoe rolled if the animal's work permits the use of this kind of a shoe.
The margins of a quarter-crack and the wall just posterior and below it
should be cut away until quite thin. The bearing margin should then be
trimmed so that it does not rest on the shoe. A bar shoe that does not
press on the frog may be used. Light blisters to the region of the coronet
help in stimulating the growth of the horn. Rest is advisable.
CORNS.--This term is applied to injuries to the foot caused by bruises or
continuous pressure to the posterior portion of the sole. This condition is
common in the forefeet.
_The predisposing causes_ are faulty conformation that favors pressure from
the shoe on the sole between the bars and wall and weak heels. Corns are
commonly met with in feet having contracted quarters. The principal
_external causes_ are wrong methods of shoeing and allowing the shoes to
remain on the feet for too long a period.
_A common symptom_ of corns is lameness. In order to relieve the pressure
over the inflamed part, the animal stands with the foot slightly flexed at
the fetlock. The lameness is not characteristic. It is only by a local
examination of the foot, made by pressing on the sole or cutting away the
horn, that we are able to form a positive diagnosis.
We describe the _diseased changes_ by using the terms _dry_, _moist_ and
_suppurative corns_. In the _dry corn_ we find the horn stained and
infiltrated with blood. In the _moist corn_ the hoof may be colored the
same as in the former, but in addition there is a space between the
vascular and horny tissue that is filled with a serous-like fluid. If this
collection of fluid becomes infected with pus organisms and is changed to
pus, it is then termed a _suppurative corn_. Sometimes the pus pushes its
way upward and backward between the sensitive laminae and the wall, and
makes its appearance at the margin of the coronary band in the region of
the quarters or heels. This usually occurs when the tissues beneath the
horny frog become bruised or the sensitive tissue pricked by a nail. It is
commonly termed "gravelled." Pus rarely breaks through the thick horny
tissue, but follows the wall and breaks through the skin where it meets
with the least resistance. Corns may be considered a serious unsoundness in
driving horses.
_The treatment_ is largely preventive. Trimming the foot and fitting the
shoe properly are important preventive measures. The practice of cutting
away the bars and sole or "opening up the heels," as it is commonly termed,
should be condemned. This method of trimming the foot instead of preventing
corns is a very common factor in producing them. The shoe should not be too
short or too narrow. It should follow the outline of the wall and rest
evenly on its bearing margin. If this is practised, weakening the wall by
cutting off that portion allowed to project beyond the shoe is unnecessary.
Feet that have low heels and large, prominent frogs should be shod with
shoes thick at the heels. The best line of treatment for a horse that is
subject to corns is to remove the shoes and allow the animal to run in a
pasture. If this is impossible, poulticing the feet or standing the animal
in moist clay will help in relieving the soreness. Excessive cutting away
of the horny sole is contra-indicated. Suppurative corns should be given
proper drainage and treatment.
LAMINITIS, "FOUNDER."--This is an inflammation of the sensitive or vascular
stricture of the foot. The inflammation may be acute, subacute or chronic.
Stockmen frequently use a classification for laminitis based on the causes.
Feed, road and water founder are common terms used in speaking of this
disease. The inflammation is usually limited to the front feet.
_The causes_ of laminitis are overfeeding, sudden changes in the feed,
drinking a large quantity of water when the animal is overheated,
overexertion, exhaustion and chilling of the body by standing the animal in
a cold draft. It may be associated with such diseases as rheumatism,
influenza and colic.
_The symptoms_ vary in the different forms of the disease. Pain is the most
characteristic symptom. The sensitive or vascular structure of the foot has
an abundant supply of sensory nerves, and, as it is situated between the
hoof and the bony core, the pressure and pain resulting from the
inflammation are severe.
In the _acute form_ general symptoms are manifested. The appetite is
impaired, the body temperature elevated and the pulse beats and
respirations quickened. If the inflammation is severe, the animal prefers
to lie down. This is especially true if all four feet are inflamed. In most
cases the horse stands with the forefeet well forward and the hind feet in
front of their normal position and under the body. The affected feet are
feverish and very sensitive to jarring or pressure. Moving about increases
the pain in the feet, and it may be very difficult to make the animal step
about the stall.
In the _subacute form_ the symptoms are less severe. The irregularity in
the gait is especially noticeable when the animal is turned quickly. The
local symptoms are less marked than in the acute form and the general
symptoms may be absent.
_The chronic form_ is characterized by changes in the shape and appearance
of the hoofs (Fig. 43). The wall shows prominent ridges or rings, the toe
may be concave, thick and long and the sole less arched than usual, or
convex. The degree of lameness varies. It is more noticeable when the horse
is moved over a hard roadway than if moved over soft ground. One attack of
laminitis may predispose the animal to a second attack.
_The prognosis_ depends on the character of the inflammation and the
promptness and thoroughness of the treatment. Acute laminitis may respond
to prompt, careful treatment in from ten to fourteen days. Subacute
laminitis responds readily to treatment. The prognosis is least favorable
in the chronic form.
_The preventive treatment_ is very important. Dietetic causes are
responsible for a large percentage of the cases of this disease. Horses
that are accustomed to being fed and watered at irregular periods and after
severe or unusual exercise seem to be able to stand this treatment better
than animals that are more carefully cared for, but even this class of
animals do not always escape injury. Stockmen should realize the danger of
producing an inflammation of the feet by feeding grain and giving cold
water to horses immediately after severe exercise. Overfeeding should also
be avoided. Careful nursing may prevent the occurrence of laminitis as a
complication of other diseases.
[Illustration: FIG. 43.--This foot shows the changes in shape and
appearance of wall and sole occurring in chronic laminitis.]
_The treatment_ of the inflammation is as follows: The removal of the shoes
and the necessary trimming of the foot should be practised early in the
inflammation; the horse should be placed in a roomy box-stall that is well
bedded with cut straw; during the cool weather it may be necessary to
blanket the animal; if the weather is hot and the flies annoy the patient,
the stall should be darkened; in serious cases, and when the animal is
heavy, it may be advisable to use a sling; hot water fomentations are to be
preferred; the patient may be stood in a tub of hot water or heavy woollen
bandages that have been dipped in hot water and wrung, out as dry as
possible may be applied to the feet; the temperature of the water should be
no hotter than can be comfortably borne with the hands; the results of this
treatment depend on the faithfulness with which it is carried out; a
poultice of ground flaxseed should be applied to the foot at night, or
during the interval between the foot-baths. This treatment may be continued
until the acute inflammation has subsided.
If the animal is inclined to eat, it should be fed very little roughness
and grain. Soft feeds are to be preferred, and one quart of linseed oil
given as a physic. After a period of from ten days to three weeks,
depending on the tenderness of the feet, the wall at the toe should be
shortened, the sole trimmed if necessary, flat shoes rolled at the toe
placed on the feet, and the animal allowed to exercise a short time each
day in a lot or pasture. As the hoof grows rapidly, it is necessary to trim
it carefully every three or four weeks and replace the shoes. The wall at
the toe should be kept short, but excessive thinning of the sole should be
avoided.
The same line of treatment as recommended for the horse may be used for
laminitis in cattle. If marked diseased changes occur in the feet, it is
not advisable to attempt the treatment of chronic laminitis, unless it is
in valuable breeding animals.
QUESTIONS
1. Give a general description of the foot.
2. State the nature and causes of side-bones.
3. What are the causes of navicular disease? Give symptoms and treatment
4. What are corns? Give the treatment.
5. Give the nature and treatment of quarter- and toe-cracks.
6. Give the symptoms and causes of laminitis.
7. Give lines of treatment to be followed in the different forms of
laminitis.
8. How may laminitis be prevented?