A. Changes of Form.
1. The Flat and the Full Hoof
(Dropped Sole).
(a) Flat Hoof.—A flat hoof is one whose toe and side walls are inclined very obliquely to the ground-surface, and whose sole is on a level with the bearing-surface of the wall.
It exists most often in horses bred in low-lying, marshy countries.
Frequently the frog is well developed, and projects considerably beyond the level of the wall. The branches of the sole sink perceptibly under the weight of the body, much more than in better-formed hoofs.
Fig. 200.
Cross-section of a shod flat foot: a, sufficiently high bearing-edge of wall, and a horizontal bearing-surface on the shoe; b, insufficient height of bearing-edge of wall, and therefore a corresponding downward and inward inclination of the bearing-surface of the shoe.
Preparing the Hoof for the Shoe.—The rule is to spare the plantar surface of the foot. After removing from the sole what little loose horn there may be, level the usually deficient bearing-surface of the wall with the rasp. The outer border of the wall, especially at the toe, should be rounded off rather more strongly than usual, because the toe requires and will bear considerable shortening. Outward bendings of the lower border of the wall should be removed as far as it is practicable to do so.
The shoe, which should be rather wider in the web and thicker than usual, should have its bearing-surface shaped to correspond to the bearing-surface of the wall; that is, if the bearing-surface of the wall is below the margin of the sole (the sole of the foot being uppermost), then the bearing-surface of the shoe should incline downward and inward ([Fig. 200, b]). The bearing-surface of the branches, however, must always remain horizontal. The shoe always requires deep concaving, especially along the inner branch of the sole. If the quarters are weak, the walls defective, or there are corns, cracks, loose walls, or other diseases of the hoof, a bar-shoe should be selected.