INFLAMMATIONS OF THE PODODERM (PODODERMATITIS).
1. Nailing.
Wounds of the velvety tissue of the sole or of the podophyllous tissue
of the wall, caused by nails which have been driven into the hoof for
the purpose of fastening the shoe, are usually termed “nailing.”
We distinguish _direct_ and _indirect_ nailing; the former is noticed
_immediately_, the latter _later_.
In =direct= nailing the nail passes directly into the pododerm (velvety
tissue of the sole, podophyllous tissue); the wound produced may vary
from a simple puncture of the pododerm to chipping of the border of the
os pedis, and is =always accompanied by bleeding=, even though it may
not always be noticed.
In =indirect= nailing the nail does not pass entirely through the horn
capsule, but very close to the sensitive tissues, and crowds the soft
horn inward against them. This inward bulging presses upon the pododerm
and causes inflammation and lameness, which may not manifest themselves
for several days.
_Symptoms._—The first symptom of direct nailing is =instant pain=
indicated by flinching or a jerking of the limb, showing that the nail
has taken a wrong course, and then a more or less profuse hemorrhage.
Usually the blood flows from the nail-hole, or the nail when withdrawn
may merely show a bloodstain at its point; however, internal bleeding
may occur without any external manifestations. The symptoms of indirect
nailing are entirely different. In this case _pain does not arise
immediately_, but later, sometimes as soon as the horse attempts to
bear his weight upon the shod foot. In the latter case, on holding up
the opposite foot the animal sways backward and throws his weight
upon the holder, or becomes restless. As a rule, the consequences
of indirect nailing are first manifested after two or three days,
infrequently from the eighth to the fourteenth day, as inflammation
within the hoof and lameness, at which time a careful examination
will usually reveal increased warmth of the hoof, pain upon pressure
with the hoof-testers and on tapping the hoof lightly, some swelling
of the entire foot, increased pulsation of the digital arteries, and
unwillingness of the animal to place all or perhaps any of its weight
upon the foot.
_Suspicion of nailing_ should be entertained if the shoeing be recent,
the hoof appear too small in relation to the body-weight, the walls
have been thinned by rasping or have been broken away, or if the nails
have been driven too high or very irregularly.
_Causes._—The most common causes are mistakes in shoeing. In the
majority of cases the cause is a disregard of the rule that the =nails
should penetrate the white line= (see pages 118, 119 and 130, heavy
type). 1, using badly-punched shoes; 2, excessive paring and shortening
of the hoof; 3, weakening of the lower border of the wall by excessive
rasping away of the outside (Fig. 187, _c_); 4, mistakes in fitting
the shoe, especially applying shoes that are too narrow, letting the
toe-clips too deep into the horn, by which the nail-holes near the toe,
instead of falling upon the white line, are carried back upon the edge
of the sole, or using shoes in which the nail-holes are too wide or
improperly directed; 5, using nails that are split, incomplete, badly
formed and bevelled, and too large; 6, starting nails too deep or with
the bevel on the outside, or drawing them too tight. As occasional
causes may be mentioned: 7, old nail-stubs in the horn; 8, walls
that are very thin or broken away; 9, a soft, crumbling wall, which
alters the sound and feeling of the nail as it is driven, and makes it
difficult to judge of its course; 10, restlessness of the animal while
being shod.
_Examination._—Press with the hoof-testers upon the sole and clinches;
tap lightly upon the clinches. If these acts cause pain, there can be
little doubt that the nail is responsible for the damage. Remove the
shoe by drawing each nail separately and carefully. Examine the nails
with reference to their direction and size, as well as to staining
with blood, blood-serum, or pus. Immediately after removing the shoe,
look for the point of entrance of each nail into the hoof, and if a
nail-hole be found upon the edge of the sole (Fig. 187, _b_) instead
of in the white line, it is highly probable that the nail which passed
in at that place pressed upon the sensitive tissues of the foot. Every
nail-hole should then be searched by passing a clean new nail into it
and pressing its point towards the soft tissues at various depths; any
indication of pain caused by this act is pretty sure proof of nailing.
It stands to reason that the character of the nail-holes in the shoe
should be closely examined.
[Illustration: FIG. 186.
Cross-section of a shod hoof, the hoof-skin or pododerm being in red:
_a_, indirect nailing where backsetting has been overdone and has bent
the nail; _b_, nail properly placed and of correct shape.]
[Illustration: FIG. 187.
Front hoof deficient in horn: _a_, right position of the nail-holes in
the white line; _b_, faulty position inside of the white line; _c_,
wall weakened by excessive rasping.]
_Treatment._—When the foot has sustained an ordinary simple prick with
a nail, the latter should be left out and the hole well filled with
wax. As a rule, no serious results follow. In severe direct nailing
the entire shoeing should be most carefully examined, and only after
everything is found to be right, and the shoe fits in such a manner
that the nails can only penetrate the wall from the white line, can it
be regarded as correct. The offending nail-hole is then to be closed
with wax. According to the intensity of the wound we may expect a more
or less pronounced inflammation of the pododerm, and this is to be
combated by resting the animal and cooling the foot.
If the wound is clean and recent, enlarging the opening in the horn by
cutting and boring can have no reasonable object; the wound by such an
act will not be made smaller, but larger.
Frequently, however, the wound is not observed or suspected until the
pain has become very intense (indirect nailing, nail-pressure); in
such cases the offending nail when withdrawn is apt to be covered with
pus or a dark, thin, ill-smelling liquid. In such a case the liquid,
whatever its nature may be, must be given free escape. In order to
accomplish this it is entirely sufficient to cut away a section of
the wall from the nail-hole outward, not greater than the width of
the little finger, and then to assist in the discharge of the pus
by placing the foot in a warm bath; it is entirely wrong, in fact,
reprehensible, to remove all horn of the wall and sole which has been
loosened from the soft parts by the suppurative process. After the
escape of the inflammatory fluids, the wall and sole will form the
best-fitting and most suitable protective dressing for the diseased
region until it has secreted new horn. If, after removal of the nail
and pus, the pain does not diminish, warm disinfecting baths of one to
two parts of creolin, or the same amount of lysol, to one hundred parts
of water at a temperature of about 90° F. will be of especial benefit;
they will not only soften the horn, but by their moisture and warmth
will directly diminish the pain and have a healing influence upon the
suppurating surfaces. The warm baths must actually _be warm and be kept
warm_. Antiseptic solutions at room temperature are much less efficient.
If the pain has not been very pronounced, or if it has been greatly
alleviated by two or three warm baths, then, as a rule, it is
sufficient to put a few drops of creolin upon the inflamed surface, and
to close the opening with oakum (carbolized oakum or carbolized cotton
is better).
The horse which has been nailed will be again perfectly serviceable
after a few days if shod with a shoe which does =not press= upon the
inflamed region. _The shoe does not press when it rests only upon the
bearing-edge of the wall, when the white line and the edge of the sole
are entirely free of the shoe, and no nails are driven in the immediate
vicinity of the wound._
Even though, as we have seen, nailing in the great
majority of cases is not particularly serious to
the horse and owner, yet we should never forget
that tetanus (lockjaw), a disease which is nearly
always fatal to horses, may follow. Nailing, however
insignificant it may seem, may under conditions lead
to the death of the horse.
2. Street-Nail.
The _condition_ caused by accidental injury of the sensitive structures
covered by the horny sole, such as the velvety tissue of the sole and
frog, plantar cushion, perforans tendon, navicular bone, os pedis, or
the pedal articulation, by sharp objects, especially nails, is called
“penetrating street-nail,” or simply “street-nail.” The resistance of
the ground to the weight of the body drives these penetrating objects
through the sole or frog into the foot.
Hind hoofs are more often affected than fore-hoofs. A favorite point of
entrance is the lateral lacuna of the frog. Street-nail is favored by
excessive thinning of the sole and frog.
_Symptoms._—The symptoms are, as a rule, sudden pain followed by
lameness. The first assistance is usually sought in the shoeing shop.
If the cause of lameness be found to be a penetrating nail, piece of
glass, or other pointed foreign body, it must be _carefully drawn out_,
in doing which we should remove the _entire object_, not allowing
pieces to break off and remain in the wound. Since it is always
important to know in what direction and how deep the foreign body has
penetrated, in order to be able to estimate the gravity of the wound,
it is advisable in all cases to preserve the penetrating body, that it
may be shown to the veterinarian, in case his services are required.
[Illustration: FIG. 188. Shod hind foot, with splint dressing.]
In slight injuries to the velvety tissue of the sole or frog,
accompanied with moderate pain, it is of no benefit to enlarge the
opening, though the horn of the sole or frog should be thinned for
the space of an inch or more around the wound, followed by cooling
applications. Deep, penetrating wounds accompanied with intense pain
require the attention of a veterinarian.
Often some form of dressing is necessary, and this is usually held in
place by a special shoe. For slight injuries, such _splint-dressings_
as are shown in Figs. 188 and 189 are sufficient. Whether such a
dressing be applied to the front or hind feet, the shoe should be _well
concaved_ upon the hoof-surface. The dressing is held in place by thin
splints of tough wood, which are firmly wedged between the shoe and
hoof.
[Illustration: FIG. 189. A practical “splint shoe” for hospital use.]
In those rare cases in which it is necessary to maintain continuous
pressure upon the seat of the wound, and to protect the entire
plantar surface of the hoof, a _covered shoe_ (Figs. 190 and 191) is
recommended. This shoe is provided with a sheet-iron cover, having at
the toe a spur which fits into a corresponding hole in the toe of the
shoe, and fastened at the heels by means of screw heel-calks.
3. Calk-Wounds of the Coronet.
All tread-wounds of the coronet, caused by the calks of the opposite
shoe, by the shoes of other horses, or by forging, are known as calk
wounds, or simply as “calking.” The injury itself is either a bruise
or a bruised wound, followed by inflammation of the coronary cushion
and an interruption in the formation of horn at that point. It occurs
most often in winter from sharp calks, especially on the hind feet. The
common seat of the injury is the coronet of the toe and inner side of
the foot.
[Illustration: FIG. 190.]
[Illustration: FIG. 191.
Shoe with cover-plate for street-nail treatment; suitable where
pressure-dressing is desired: _a_, hole in the bottom of the toe-calk
for reception of spur, _b_, of cover-plate; _c_, holes for reception of
screw-calks, _d_, which fasten the cover-plate to the shoe.]
The inflammation terminates either in resolution—that is, passes
gradually away, leaving the tissues apparently normal—or in
suppuration. The perioplic horn-band, which is usually loosened from
the perioplic band by the injury, does not again unite. For this
reason, and because of the interruption in the formation of horn at the
seat of injury, there results a transverse depression or cleft in the
wall.
The shoeing has to deal only with the lameness that may be present as
a result of the calking. The section of the wall containing the lesion
should be shortened, so that it will not press upon the shoe. Serious
calk-wounds, as a rule, require treatment by a veterinarian.
4. Corns (Bruised Sole).
The expression “corns” is applied to nearly all bruises of the pododerm
of the posterior half of the foot, with the exception of the frog,
which are apparent to the eye as yellowish, reddish, or bluish-red
discolorations of the horn of the sole and white line.
The surface of the pododerm (fleshy leaves and villi) is chiefly
involved, and almost without exception there is rupture of small
blood-vessels and an outpouring of blood between the pododerm
and the horn. The blood penetrates the horn-tubes and causes the
above-mentioned staining. By subsequent growth of horn these stained
patches are carried downward, and are finally uncovered and brought to
sight in paring the hoof.
The seat of corns is either on the fleshy leaves of the quarters, or on
the velvety tissue of the sole in the angle between the wall and the
bar, or on the fleshy leaves of the bars. Thus we distinguish _corns of
the wall, sole, and bars_.
Corns affect chiefly the front hoofs, and more often the inner half
than the outer. Unshod feet are seldom affected.
According to the intensity of the lesions we distinguish:
1. _Dry Corns._—The red-stained horn is dry, and there is seldom
lameness.
2. _Suppurating Corns._—They are the result of intense bruising
followed by inflammation. The pus is either thin and dark grayish
in color, denoting a superficial inflammation of the pododerm, or
yellowish and thick, denoting a deep inflammation of the pododerm. In
the latter case a veterinarian should be called. Lameness is usually
pronounced.
3. _Chronic Corns._—In this case there is vivid discoloration of horn
in all possible hues. The horn is either soft, moist, and lardy, or
crumbling, cracked, and at times bloody. The inner surface of the
horn capsule has lost its normal character, and is covered with horny
swellings or nodules (Fig. 192, _a_). Sometimes the wing of the os
pedis on that side has become morbidly enlarged and loosened. A short,
cautious gait alternates with well-marked lameness; the latter appears
whenever the shoe presses too firmly on the corn, or when the hoof
becomes too dry.
[Illustration: FIG. 192.
Inner aspect of a quarter of a hoof, showing changes in the horn-leaves
due to chronic corns: _a_, horny tumor resulting from the disease.]
_The causes_, aside from the form and quality of the hoofs and the
position of the limbs, lie in injudicious dressing of the hoof and
in faulty shoes. Too much trimming of wide and flat hoofs, excessive
weakening of the quarters, sole, bars, and frog of all other hoofs,
while the toe is usually left too long, are the usual causes.
Shortening one quarter too much in relation to the other, so that the
foot is unbalanced and the lower side overloaded, is a frequent cause.
Hollowing the sole and bars excessively and unnecessary thinning of the
branches of the sole in the search for corns are also causes.
Among faulty shoes we may mention those not level on the hoof-surface,
trough-shaped, too short in the branches, shoes which do not completely
cover the bearing-surface of the hoof, or whose bearing-surface at
the ends of the branches is directed downward and inward so that the
quarters are squeezed together when the weight is put on the foot.
Insufficient concaving of the shoe is often an exciting cause of corns
in flat feet and in those with dropped soles. A well-formed shoe
which does not rest firmly upon the hoof, or which has been shifted
as a result of careless nailing, may as readily cause bruising of the
quarters as neglected shoeing. The latter causes, as a rule, corns of
the sole. It is very rarely that corns are caused by stones fastened
between the frog and branches of the shoe or in unshod hoofs by pebbles
becoming wedged in the white line.
_Dryness_ is particularly injurious to the hoofs, and is in the highest
degree favorable to the production of corns. It renders the hoof stiff
and inelastic, and first manifests itself by a short, cautious (sore)
gait when the horse is first put to work.
_Treatment._—First, removal of the causes, by restoring the proper form
to the hoof through shortening a toe which is too long (especially apt
to be the case in acute-angled hoofs), cutting down quarters which are
too high, and carefully removing all dead horn from the branches of the
sole, especially in acute-angled hoofs.
Deeply digging out a small area of blood-stained horn is injurious.
It is much better to thin the horn of the entire branch of the sole
uniformly, in doing which we should avoid wounding the velvety tissue
of the sole or drawing blood.
The proper shoe is the =bar-shoe=, except when both cartilages are
ossified. The pressure should not be taken from the quarters unless
they are sore.
When there is a _suppurating corn_, the shoe should be left off several
days. A _chronic corn_ should be protected continuously from pressure
by the shoe. This is accomplished by using a bar-shoe with leather
sole. _A three-quarter shoe is not sufficient to properly protect a
hoof affected with a chronic corn, if the animal must perform exacting
labor on hard roads._
The care of the hoof consists in keeping it cool, moderately moist, and
pliant.
5. Inflammation of the Heels.
Inflammation of the bulbs of the plantar cushion (heels) is usually
caused by such external influences as bruising. It occurs in both shod
and unshod feet. The symptoms are: increased warmth, pain and swelling,
sometimes infiltration of the tissues with blood, accompanied by a
short, cautious gait, or, if only one foot is affected, by well-marked
lameness.
The _most frequent causes_ are: going barefoot upon hard (frozen),
uneven ground; shoeing hoofs having low heels with flat shoes that are
too short; sometimes too much frog pressure by the bar of a bar-shoe;
forging and grabbing.
The treatment first indicated is a cooling application in the form of
an ice-poultice, or a soaking in cold water. Later, astringent (drying)
applications are of benefit, especially if the perioplic horn-ring
has partially loosened from the bulbs of the heels; for example, a
weak solution in water of sulphate of copper (1 to 20), followed by
the application of a shoe with heel-calks, which is quite long in the
branches and _which must not press upon the wall of the quarters_.
6. Laminitis (Founder).
By this name we designate a peculiar inflammation of the pododerm at
the toe. It arises suddenly in well-nourished and apparently healthy
horses, following excessive work or long-continued rest in the stable,
and frequently leads to a decided change of form of the hoof.
The disease is always accompanied with intense pain. It most often
affects both front feet, more rarely all four feet, or only one foot.
In the first case the two front feet are planted far in advance of
the body, and the hind feet well forward under the belly. When all
four feet are affected, travelling is exceedingly difficult, often
impossible; in this case there is nearly always a high fever over the
entire body.
The seat of the disease is in the fleshy leaves about the toe, more
rarely upon the side walls and quarters. Depending upon the intensity
of the inflammation, the fleshy leaves are more or less loosened
from the horny leaves, as a result of which there is a change of
position of the os pedis, with a simultaneous sinking of the coronet
at the toe. This produces a change of form of the hoof. The quarters
become higher. Rings form upon the wall, and their course is quite
characteristic of the disease. At the toe these rings are quite close
to one another, but as they pass back towards the quarters they
gradually separate from one another and recede from the coronary band
(Figs. 193, 194, and 195).
[Illustration: FIG. 193.
Vertical longitudinal section of a foot altered by chronic laminitis:
_a_, hollow wall at toe thrust forward; _b_, leafy layer much thickened
and crumbling (“seedy-toe”); _c_, dotted line showing limit to which
the toe may be rasped away in shoeing; _d_, dropped sole; _e_, atrophy
of lower sharp edge of os pedis; _g_, dotted line indicating the height
of the perioplic band; _h_, foot axis.]
The wall at the toe is sunken just under the coronet; its lower part,
on the contrary, is thrust forward. _Later, the white line becomes
pathologically widened._ The horn of the white line is dry, crumbling,
and easily broken down, so that a break in continuity (crack) is apt to
occur between the wall and sole, and lead to the formation of a _hollow
wall_ (“seedy-toe”). Where the inflammation is moderate and is not
repeated, healing usually takes place and the horn grows down regularly
and in normal direction from the coronet. However, a rather brittle
condition of the horn remains permanently. If, on the contrary, the
inflammation was very severe or repeated several times, the horny sole
becomes flat just in front of the point of the frog as a result of the
sinking of the os pedis, or it may even drop below the level of the
wall (full hoof, dropped sole). Indeed, it even happens at times that
the toe of the os pedis perforates the horny sole just in front of the
point of the frog. The wall at the toe, which was previously but little
altered in form, is now thrust prominently forward.
[Illustration: FIG. 194. Foundered foot (chronic laminitis), before
dressing.]
[Illustration: FIG. 195.
Foundered foot, dressed and shod. The dotted lines indicate its form
before being dressed,—_i.e._, as shown in Fig. 194.]
The inflammation of the pododerm may under certain conditions and by
skilful veterinary treatment be removed, so that the characteristic
changes of form and quality of the hoof will not occur. But if this is
not accomplished, as is often the case, the disease will be obstinate,
and permanent morbid changes of the horn capsule take place.
[Illustration: FIG. 196.
A hoof altered by chronic laminitis; shod with an open flat shoe: _a_,
wall at the toe does not bear on the shoe; _b_, clip at the end of the
branch to oppose the tendency of the shoe to slip forward when half
worn out.]
A horse in such a condition can be used, but the gait will be short
and stiff. The hoofs are shuffled forward and set heels first to the
ground, a manner of travelling that rapidly wears away the branches of
the shoe.
In dressing a foundered hoof the outer circumference of the sole is
the guide. The thick projecting wall at the toe may be removed with
the rasp without injuring the foot. The sole should be spared, but the
quarters should be lowered to improve the setting of the foot to the
ground.
The choice of the shoe will depend upon the shape and nature of the
sole. If this is still concave, an ordinary shoe may be used. If,
however, the sole is flat or dropped, it must be protected by an open
shoe with a broad web, or with a bar-shoe (Fig. 197), which is of
especial value when the bearing-edge of the wall is weak or broken away.
[Illustration: FIG. 197.
A well-covered (wide-webbed) bar-shoe, with two lateral toe-clips and
an end-clip, for a foundered foot.]
[Illustration: FIG. 198. An open shoe for a foundered foot with a
dropped sole.]
As long as there is pain on pressure about the toe there should be no
toe-clip, but two side-clips. The wall between these clips should be
lowered a tenth to an eighth of an inch to prevent pressure of the shoe
upon the sensitive tissues of the toe (Fig. 195). The nails should be
as small as possible and placed well back towards the quarters. No nail
should be driven in the wall at the toe when there is separation of
sole and wall at the toe (hollow wall, seedy-toe).
The shoes of horses affected with founder often work forward as a
result of the animals travelling upon their heels. To prevent this
evil, clips may be raised at the ends of the branches of an open shoe,
or one clip in the middle of the bar, in case a bar-shoe is used (Fig.
197).
7. Keraphyllocele (Horn Tumor).
A keraphyllocele is a more or less sharply bounded horn tumor
projecting from the inner surface of the wall.
[Illustration: FIG. 199.
A section of wall at the toe showing a Keraphyllocele (horn-leaf
tumor): _a_, coronary border; _b_, plantar border; _c_, body of tumor;
_d_, base of tumor presenting funnel-shaped opening discharging pus.]
Its occurrence is rare. Its favorite seat is at the toe. It rarely
causes lameness. It can only be diagnosed with certainty when it
extends downward to the lower border of the wall. In this case there
may be seen a half-moon-shaped thickening of the white line which
rounds inward upon the edge of the sole, and is of a waxen color.
Frequently the horn at this place crumbles away, leaving a more or less
dark-colored cavity from which there sometimes escapes a small quantity
of dark-grayish pus.
_Causes._—Chronic inflammation of the podophyllous tissue, resulting
from compression or bruising. Keraphyllocele frequently follows a
complete toe-crack of long duration, or a deep calk-wound at the
coronet.
_Prognosis._—Unfavorable, whether there is lameness or not. If there
is no lameness it is very apt to arise later, and if lameness is
already present it can only be removed by an operation, which should be
performed by a veterinarian. A return of the lameness following hard
work at a trot upon hard roads is always to be feared.
_Shoeing._—An ordinary shoe well concaved underneath the inflamed
region, which should be relieved of all pressure.[5]
[5] Should lameness persist, it will be necessary to remove a strip of
the wall from the plantar border to the coronet in order to remove the
horn tumor. The fleshy leaves which have secreted the tumor must be
extirpated and the surface of the os pedis well scraped, or the growth
will return.