Tarsal (Hock) Problems
The tarsus is a complex joint that consists of a number of bones and ligaments. Most notable of the bones are the talus and calcaneus. The talus is the main portion of the joint that communicates with the tibia to form the primary motion joint of the hock. It has two large ridges that allow motion in flexion and extension and provide stability. The calcaneus is a large bone that protrudes in the back of the joint, forming the point of the hock. The Achilles tendon, or common calcaneal tendon attaches there.
Osteochondritis dissecans (OCD)
OCD can occur in a number of joints, including the hock. It has a genetic basis, as well as environmental factors, including rapid growth rate, obesity, and high loads on joints. The condition occurs when joint cartilage does not turn into bone as part of the normal growth process, resulting in excess cartilage thickness. This area is weak, and as a result, a fragment may break off. In the tarsus, the result is pain, lameness, decreased range of motion, joint swelling, and arthritis.