<P> Self - adapting capabilities of the hooves show their maximal effectiveness in wild equids (but domesticated horses show this too, to a lesser extent), as shown by the perfect soundness of feral horses, such as Mustangs, in a wide variety of environments . </P> <P> Equid hooves are the result of the 55 - million - year evolution of the horse . Wild and domesticated Equus species share a very similar hoof shape and function . The present - day conformation of the hoof is a result of a progressive evolutionary loss of digits I, II, IV and V of the basal pentadactyl limb, with changes in bones, joints and hoof capsule . The resulting conformation allows a heavy, strong body to move with high speed on any ground, and most efficiently on open, hard, flat areas like prairies and deserts (i.e.,' cursorial specialisation'). </P> <P> There are several disorders and injuries that can affect the equine hoof . Laminitis and navicular disease are two of the most serious . Thrush and white line disease, common bacterial infections, can become serious if left untreated . Quiltor, an infection of the lower leg that can travel under the hoof, is also sometimes seen, although most commonly in draft horses . </P> <P> Quarter cracks are vertical splits in a hoof wall, most commonly seen on the inside of the front hooves or the outside of the hind hooves . They can result from poor shoeing and management practices, natural hoof conformation, or injuries to the leg and hoof . </P>

Hoof is to horse as paw is to