GENERAL REMARKS CONCERNING THE SHOEING OF DEFECTIVE HOOFS AND LAME
HORSES.
The boundary between health and disease of the hoof is difficult to
determine, especially when we have to deal with minor defects of
structure or shape of the hoof. Ordinarily, we first consider a hoof
diseased when it causes lameness. However, we know that diseases of the
hoof may exist without lameness. Therefore, a hoof should be regarded
as diseased or defective when the nature of the horn, the form of the
hoof, or the parts enclosed by it, deviate from what we consider as
normal or healthy (see page 81), whether the service of the animal is
influenced by it or not.
Front hoofs become diseased or defective more readily than hind
hoofs, because they bear greater weight, have more slanting walls,
and are more exposed to drying influences. =All normally wry hoofs
and acute-angled hoofs become more readily diseased than regular and
upright (stumpy) hoofs.=
The _indications_ of the various diseases of the hoof are discussed
in the following chapters. We shall in this chapter undertake only
a brief general discussion of _inflammation of the pododerm_. This
inflammation, known as =pododermatitis=, always manifests itself by
_lameness_ and, under closer examination of the foot, by _increased
warmth_, _pain_, and _stronger pulsation of the digital_ and _plantar
arteries_. The pain produces either a _timid, shortened_ (sore) _gait_,
or well-marked _lameness_, especially upon _hard_ ground. Increased
sensitiveness of the pododerm is detected by compression of the hoof
with the pincers (hoof-testers), or with greater certainty by lightly
tapping the hoof. The increased warmth of a part or of the entire
hoof is detected by feeling with the hand. Intense pain and greatly
increased warmth, with a moderate, diffuse swelling of the soft parts
between the hoof and fetlock-joint, indicate suppuration within the
hoof.
_The examination_ of horses lame in the feet must always be cautious
and searching, and should begin with the moving and judging of the
horse as already described on page 90. The faults detected in the hoof
or in the shoeing, the pain and increased warmth of the hoof, will not
leave us in doubt as to whether the animal is lame in the hoof or not.
However, should there be a doubt, we must carefully examine all the
joints and tendons of the foot and, if necessary, of the limb above,
and observe the animal’s manner of travelling at a walk and at a trot,
on soft and on hard ground, in a straight line and in a circle.
The =removal of the shoe= should be performed with =greatest caution=.
Under certain conditions the second shoe should not be removed until
the first has been replaced. The same caution must be observed in
paring the hoof, which is to be regarded as a part of the examination
of the hoof. The paring of a hoof for this purpose often differs
somewhat from the preparation of a sound hoof for the shoe, and while
it is necessary because it frequently furnishes the first trustworthy
indication of the trouble, it must be done with circumspection and
intelligence.
The _causes_ of diseases of the hoof are very numerous, for many
external influences act injuriously upon the hoof. In addition to
too great dryness, want of care (neglected shoeing), and premature,
unreasonable, cruel use of the horse, should be mentioned particularly
_injudicious dressing of the hoof and direct and indirect faults in
the shoeing_. The pododerm, shut in between the hard os pedis and the
stiff, unyielding horn capsule, is frequently exposed to bruising
and other injuries, from which arise most of the defects of the hoof
itself. All these things lead, under certain conditions, to lameness.
[Illustration: FIG. 185. Bar-shoe for right foot.]
_Treatment._—First of all, the discovered causes should be removed,
or, if this is not possible, as is frequently the case, they should be
ameliorated. Very often the lameness may be removed by proper shoeing,
a change in the animal’s work, and better care of the hoof. When there
is intense inflammation within the foot, the shoe should be removed
for a few days. When the inflammation is moderate and confined to a
small area, it is usually sufficient to alter the shoeing by regulating
unnatural relations of height in the different parts of the wall, and
by removing all superfluous horn from the wall and sole (to a less
degree from the frog), partly for the purpose of rendering the horn
capsule more yielding, and partly to make the poultices which are used
more effective. The shoe is then to be so applied that the diseased
region will be _relieved of the body-weight_, and will remain free
from all pressure from the shoe. This can be done partly by making
the underlying branch of the shoe somewhat wider and longer than the
other, and partly by cutting down the bearing-edge of the wall where
this is possible without weakening it too much, otherwise by concaving
or beating down the upper surface of the shoe. By reason of the fact
that the posterior half of the hoof is the seat of most diseases of
the hoof, it is to be recommended that the nail-holes in shoes used
in these diseases be placed as far as possible in the anterior half
of the shoe, and in some special cases distributed evenly around the
toe. Among shoes suitable for diseased hoofs the bar-shoe (Fig. 185)
holds the first place, because it renders superfluous many other shoes
specially designed for various diseases of the hoof. It is made like
an ordinary flat shoe, except that it requires a somewhat longer piece
of iron; the ends of the branches are bent inward over a dull corner
of the anvil, bevelled, laid one over the other, and welded together
to form the bar. The width and thickness of the bar should be the same
as of the rest of the shoe, and its frog-surface should be slightly
concave.
The _bar-shoe is valuable, because_ it protects from pressure diseased
sections of the wall which have been laid free, allows part of the
body-weight to be borne by the frog, and restores normal activity to
the disturbed physiological movements of the foot. By using it we can
either gain a more extensive bearing-surface for the hoof, or can make
it easier for the surface that bears the weight to do the work. If on
account of _weakness_ of the bearing-surface of the hoof, or from any
other cause, we wish to distribute the body-weight over the entire
plantar surface of the foot with the exception of the painful region,
we add a _leather sole_ to the bar-shoe.
In this case it is necessary to place holes in the ends of the branches
of the shoe, so that we may rivet the leather firmly to the shoe with
small nails. The shoe should be made somewhat wider than the hoof,
and the clips somewhat higher than usual. After fitting the shoe the
grooves for the clips are cut in the leather, the latter is riveted
to the shoe, and all leather projecting beyond the outer edge of the
shoe is trimmed away. The lacunæ of the frog and other concavities of
the sole are then thickly smeared with wood-tar and afterwards filled
up with oakum to such a degree that the packing will bear some of
the body-weight when the shoe and leather sole are in position. This
packing is of great importance, because it prevents the filtering in
from behind of sand and slime, preserves the toughness and pliability
of the horn, breaks shock, and produces a gradual expansion of the
posterior half of the hoof. Before nailing the shoe to the foot the
leather sole should be soaked in water.
Classification of Diseases of the Hoof.
INFLAMMATIONS OF THE PODODERM.
1, Nailing (pricking and close-nailing); 2, street-nail; 3,
calk-wounds; 4, corns (bruised sole); 5, bruised heels; 6, laminitis
(founder); 7, keraphyllocele (tumor of horny leaves).
DEFECTS OF THE HORN CAPSULE AND LATERAL CARTILAGES.
(_a_) Changes of form: 1, flat hoof and full hoof (dropped sole); 2,
upright hoof (stumpy or stubby hoof); 3, contracted hoof; 4, wry hoof;
5, crooked hoof; 6, ossification of the lateral cartilage (side-bone).
(_b_) Disturbances of continuity of the horn capsule: 1, cracks; 2,
clefts; 3, loose wall; 4, hollow wall; 5, thrush.