_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. CHAPTER IX. DEFECTS OF THE HOOF. 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. [Illustration: 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.