Diseases of the Horse's Foot

by H. Caulton Reeks

Symptoms.—In this case the horn of the heels, instead of running down in a straight line from the coronary margin to the bearing surface of the wall, presents a more or less distinct concavity (See Fig. 79, a, a).

As is the case with contraction considered as a whole, this deformity may affect one or both heels; and during its first appearance, which is after the first few shoeings, the animal may go distinctly lame.

Causes.—Coronary contraction may occur in hoofs of normal shape immediately shoeing is commenced, and frog pressure with the ground removed. It is far more likely to ensue, however, if the hoof is flat, with the heels low, and the wall sloping. And with those predisposing circumstances it is that the horse goes lame, and not with the hoof of normal shape.

Seeing, then, that this condition is largely dependent upon the shape of the foot, we may, to some extent, regard it as hereditary. Seeing further, however, that it only appears when shoeing is commenced, we may in a greater degree also regard it as acquired. The lesson, therefore, that this and other forms of contraction should teach us is the carefulness with which the shoeing should be superintended in a large stud, or in any case where the animal is of more than ordinary value.

FIG. 79.—HOOF WITH LOCAL OR CORONARY CONTRACTION (AS INDICATED AT THE POINTS a, a).

The explanation of the restricted nature of this form of contraction is simple enough. We have only to refer to the lessons taught by the experiments of Lungwitz, described in Chapter III., and the condition almost explains itself. We remember that, briefly, the coronary margin of the wall resembles a closed elastic ring, which yields and expands to local pressure, no matter how slight. We remember also that removal of the counter-pressure of the frog with the ground tended to contraction of the wall's solar edge when weight was applied. Connect these two facts with the experience that this form of contraction more often than not occurs in hoofs with sloping heels, and we arrive at the following:

1. The excessive slope of the heels tends to throw a more than usual part of the body-weight upon the posterior portion of the coronary margin of the wall, with a consequent expansion of that part of the coronary margin implicated.

2. That the shoeing, in removing the counter-pressure of the frog with the ground, is at the same time tending to bring about contraction of the lower portions of the wall at the heels and quarters.