In preparing a foot the wall at the toe may, from want of care, be reduced a little below the level of the sole, or in making a shoe the inside border at the toe may be left higher than the outside. In each case uneven pressure is placed on the sole just where the back border of the shoe rests. In fitting a hot shoe, wherever the hoof is unduly marked warning is given that pressure at that point must be prevented by altering the surface either of the shoe or the foot. On a strong foot, the knife may be used to remove a little horn; on a weak foot the alteration must be on the shoe.
At the the heel uneven pressure is most frequent on the angle of sole between the wall and bar, where it causes the so-called "corn"—a condition in the horse having no analogy to the affliction similarly named in the human subject. It is simply a bruise of the sensitive parts under the horn.
A bruised heel—a corn—is most likely to arise from the use of a shoe too short, especially if fitted too close. It may arise from a properly-fitted shoe retained too long on the foot and shifted from its proper bearing on the wall to an improper bearing on the sole. A bruised heel may also result from the use of a well-made shoe if the preparation of the hoof has been faulty. Rule-of-thumb directions to "reduce the heels to a level by the use of the rasp, but on no account cut away any sole" may result in injury. In a strong foot with an overgrown sole it is easy to get a level surface and to fit on to it a level shoe, but the horn of the sole does not remain level. As it grows and flakes off the portion between the bar and wall is raised. If the weather be wet it swells, and then, bound down by the shoe, it acts simply as a stone might and bruises the sensitive parts within by its uneven pressure. It is always safe and it is never injurious to remove so much of the surface of this portion of sole with the drawing-knife as will ensure no uneven pressure on it by the shoe.
Fig. 50.—An "eased" heel.
The more exactly the shoe fits the foot-surface the more easily it is retained in position by the nails, and the less likelihood there is of any part of it pressing distinctly on a limited portion of horn. Exact fitting allows all bearings and pressures to be distributed equally over the surface of the hoof, and thus permits the shoe most nearly to resemble a mere continuation of the hoof in iron—an arrangement to prevent wear, but not to interfere with natural functions. There is one departure from level fitting which requires special notice since it is made, not by accident or negligence, but by design. It consists in taking the bearing of an inch or an inch and a half of the extremity of a shoe off the foot. ([Fig. 50]). It has been called "easing the heels," and the space permits a knife-blade, sometimes even a pencil, to be placed between the shoe and the foot. It is one of the very worst practices that theory has forced into horse-shoeing. Men who do it say "the heels won't stand pressure." I reply they will stand all proper pressure, and a good deal more than the quarters. But the practice does not relieve the heels of pressure. If you examine a shoe fitted in this way, after it has done a month's service, you will find it sometimes polished bright, sometimes with a deep groove worn into it. You may also test its bearing by raising the foot from the ground and inserting between shoe and hoof a flat bit of wood, then on releasing the foot and raising the opposite one, you will find that the bearing is such that the bit of wood cannot be removed. The "eased heel" does not relieve the heels of pressure but, instead of constant normal bearing, it permits a downward movement of the back of the foot at each step—which is unnatural, and which cannot occur in an unshod foot on a level surface. The "eased heel" does more than this. It wastes a large extent of good bearing-surface, and it concentrates pressure at one point—where the shoe and foot meet—at the quarters. It loses good bearing-surface where it is important to have it, and unevenly throws extra weight on the quarters which are the weakest parts of the wall. An "eased heel" has not one single advantage, but it has every disadvantage which misplaced ingenuity could contrive.
