The hock, tarsus or uncommonly gambrel, is the region formed by the tarsal bones connecting the tibia and metatarsus of a digitigrade or unguligrade quadrupedal mammal, such as a horse, cat, or dog. This joint may include articulations between tarsal bones and the fibula in some species (such as cats), while in others the fibula has been greatly reduced and is only found as a vestigial remnant fused to the distal portion of the tibia (as in horses). It is the anatomical homologue of the ankle of the human foot. While homologous joints occur in other tetrapods, the term is generally restricted to mammals, particularly long-legged domesticated species.

Horse

The terms tarsus and hock refer to the region between the gaskin (crus) and cannon regions (metatarsus), which includes the bones, joints, and soft tissues of the area. The hock is especially important in equine anatomy, due to the great strain it receives when the horse is worked. Jumping, quick turns or stops, and movements that require collection, are some of the more stressful activities.

Primary joints and bones of the hock

In the horse, the hock consists of multiple joints, namely: In the horse, the hock consists of the following bones:

Equine disease states

Conformational defects

Also see equine conformation Because the hock takes a great deal of strain in all performance disciplines, correct conformation is essential if the horse is to have a sound and productive working life. Common conformational defects include sickle hocks, post-legged conformation/straight hocks, cow hocks, and bowed hocks. Depending on the use of the horse, some defects may be more acceptable than others.