The care of the hoofs of colts is of special importance. _Abundant exercise_ upon dry ground which is not too stony is most beneficial. Such exercise will cause the hoofs to wear gradually, and it will only be necessary from time to time to observe whether the wear is taking place uniformly, and if not, to correct the uneven wear with the rasp. [Illustration: FIG. 183. Twisted left front long pastern of colt, viewed from the upper articular surface. The lower end has been twisted toward the left: _a_, transverse axis of lower articular surface; _b_, transverse axis of the upper articular surface.] If colts are reared in the stable, the horn continuing to grow down does not undergo sufficient wear, and changes in form of the hoof, and even permanent distortions of the bones of the foot gradually occur. The wall becomes too long and bends or sometimes separates from the sole and keraphyllous layer. Weak quarters bend (curl) inward and encroach upon the space occupied by the frog (contracted feet of colts). The toe becomes too long, and this gives rise to too steep a position of the pastern and causes an insecure and diffident gait; therefore the hoofs must be shortened from time to time. The in-curved quarters should be removed with the hoof-knife, and the outer edge of the plantar border of the wall well rounded with the rasp. In the base-wide and base-narrow standing positions the outer and inner walls respectively become relatively long and induce the colt to assume a still more abnormal position. The young and pliant pasterns may thus become permanently twisted and distorted (see Figs. 183 and 184). In a hoof that is becoming awry, restoring to the wall its proper level with relation to the position of the limb will not only be invaluable in ultimately producing a good hoof, but will improve the faulty position of the limb. In exceptional cases, where the plantar border of some section of the wall gives evidence of too rapid wear, the application of a tip or of a half-shoe may be of benefit. Furthermore, we should attempt to secure greater cleanliness by frequently and thoroughly washing the hoofs and bedding with plenty of good straw. [Illustration: FIG. 184. Left front long pastern of a colt showing compression shortening of outer half: _a_, transverse axis of upper articulation; _b_, transverse axis of coronary joint, not parallel to upper axis.] Too early shoeing of young horses is very injurious; it hinders the development of the hoofs, and, furthermore, young horses when shod are frequently seriously overworked and prematurely ruined. Moderate work in the fields does not injure young horses, but for such service they do not require shoes. The unshod hoofs of older horses should be periodically rounded with a rasp and the length of the walls regulated when, by reason of a lack of exercise, proper wear has not taken place. B. Care of Shod Hoofs.