HORSE-SHOES. The horny casing of the foot of the horse and other solidungulates, while quite sufficient to protect the extremity of the limb under natural conditions, is found to wear away and break, especially in moist climates, when the animal is subjected to hard work of any kind. This, however, can be obvi ated by the simple device of attaching to the hoof a rim of iron, adjusted to the shape of the hoof. The animal itself has been in a very marked manner modified by shoeing, for without this we could have had neither the fleet racers nor the heavy and powerful cart-horses of the present day. Though the ancients were sufficiently impressed by the damage done to horses' hoofs to devise certain forms of covering for them (in the shape of socks or sandals), the practice of nailing iron plates or rim shoes to the hoof does not appear to have been introduced earlier than the 2nd century B.c., and was not commonly known till the close of the 5th century A.D., or in regular use till the middle ages. The evidence for the earlier date depends on the doubtful inter pretations of designs on coins, etc. As time went on, however, the profession of the farrier and the art of the shoesmith gradu ally grew in importance. It was only in the i 9th century that horse-shoeing was introduced in Japan, where the former practice was to attach to the horse's feet slippers of straw, which were renewed when necessary, a custom which may indicate the usage of early peoples.
In modern times much attention has been devoted to horse shoeing by veterinary science, with the result of emphasizing that methods formerly adopted caused cruel injury to horses and serious loss to their owners. According to modern principles (I) shoes should be as light as compatible with the wear demanded of them; (2) the ground face of the shoe should be plain, and the face applied to the foot concave; (3) heavy draught horses alone should have toe and heel calks on their shoes to increase foothold; (4) the excess growth of the wall or outer portion of horny matter should only be removed in re-shoeing; care being taken to keep both sides of the hoof of equal height ; (5) the shoe should fit accurately to the circumference of the hoof, and project slightly beyond the heel ; (6) the shoe should be fixed with as few nails as possible, six or seven in fore-shoes and eight in hind-shoes, and (7) the nails should take a short thick hold of the wall, so that old nail-holes may be removed with the natural growth and paring of the horny matter.