Stone bruise (horse)

A horse hoof is a structure surrounding the distal phalanx of the 3rd digit (digit III of the basic pentadactyl limb of vertebrates, evolved into a single weight-bearing digit in equids) of each of the four limbs of Equus species, which is covered by complex soft tissue and keratinised (cornified) structures. Since a single digit must bear the full proportion of the animal's weight that is borne by that limb, the hoof is of vital importance to the horse. The phrase "no hoof, no horse" underlines how much the health and the strength of the hoof is crucial for horse soundness.

Both wild and feral equid hooves have enormous strength and resilience, allowing any gait on any ground. A common example of the feral horse type is the Mustang. The Mustang is, in part, descended from the Iberian horses brought to the Americas by the Spanish, but most herds also have ancestry from other breeds. Therefore, the famous Mustang hoof strength is in part a result of natural selection and environment. Thus, it is proposed that other domestic breeds could develop similar hooves if raised under similar conditions.

The recent barefoot movement claims that such a strength can be almost completely restored to domesticated horses, when appropriate trimming and living conditions are applied, to such an extent that horseshoes are no longer necessary in almost any horse. If true, it would undermine the belief that "the horseshoe is a necessary evil."

The barefoot management system has not, however, gained a foothold among serious equine professionals, due to three factors: 1) increased strain placed on the hoof in sports, such as eventing and endurance riding, 2) the added weight of the rider and saddle, and 3) man-made surfaces, such as concrete, asphalt, and gravel, which can wear the walls down to the sensitive tissue over time.

The hoof is made up by an outer part, the hoof capsule (composed of various cornified specialized structures) and an inner, living part, containing soft tissues and bone. The cornified material of the hoof capsule is different in structure and properties in different parts. Dorsally, it covers, protects and supports P3 (also known as the coffin bone, pedal bone, PIII). Palmarly/plantarly, it covers and protects specialised soft tissues (tendons, ligaments, fibro-fatty and/or fibrocartilaginous tissues and cartilage). The upper, almost circular limit of the hoof capsule is the coronet (coronary band), having an angle to the ground of roughly similar magnitude in each pair of feet (i.e. fronts and backs). These angles may differ slightly from one horse to another, but not markedly. The walls originate from the coronet band. Walls are longer in the dorsal portion of the hoof (toe), intermediate in length in the lateral portion (quarter) and very short in palmar/plantar portion (heel). Heels are separated by an elastic, resilient structure named the 'frog'. In the palmar/plantar part of the foot, above the heels and the frog, there are two oval bulges named the 'bulbs'.

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Wikipedia