Shoe Boil - Structural Defects

Structural Defects

See also: Skeletal system of the horse An Ardennes horse Comparison of the size and structure of the legs of a racehorse (left) to that of a draft horse (right)

The ideal horse has legs which are straight, correctly set and symmetrical. Correct angles of major bones, clean, well-developed joints and tendons, and well-shaped, properly-proportioned hooves are also necessary for ideal conformation. "No legs, no horse" and "no hoof, no horse" are common sayings in the equine world. Individual horses may have structural defects, some of which lead to poor movement or lameness. Although certain defects and blemishes may not directly cause lameness, they can often put stress on other parts of the body, which can then cause lameness or injuries. Poor conformation and structural defects do not always cause lameness, however, as was shown by the champion racehorse Seabiscuit, who was considered undersized and knobby-kneed for a Thoroughbred.

Common defects of the forelegs include base-wide and base-narrow, where the legs are farther apart or closer together on the ground then they are when the originate in the chest; toeing-in and toeing-out, where the hooves point inwards or outwards; knee deviations to the front (buck knees), rear (calf knees), inside (knock knees) or outside (bowleg); short or long pasterns; and many problems with the feet. Common defects of the hind limbs include the same base-wide and base-narrow stances and problems with the feet as the fore limbs, as well as multiple issues with the angle formed by the hock joint being too angled (sickle-hocked), too straight (straight behind) or having an inward deviation (cow-hocked). Feral horses are seldom found with serious conformation problems in the leg, as foals with these defects are generally easy prey for predators. Foals raised by humans have a better chance for survival, as there are therapeutic treatments that can improve even major conformation problems. However, some of these conformation problems can be transmitted to offspring, and so these horses are a poor choice for breeding stock.