The hock joint in a horse is comparable to the ankle of a human and is comprised of six tarsal bones with four different joints. Stress on the hock will cause hock problems and lameness.
Degenerative joint disease, or spavin, is a common problem affecting the hock of a horse, according to the Louisiana State University School of Veterinary Medicine. Horses afflicted with this painful condition will become lame and get progressively worse if not treated. Spavin is commonly caused by too much work off the hind legs.
Treatment of mild cases of spavin includes corrective trimming and shoeing, managed exercise, and oral phenylbutazone for pain. Intravenous or intramuscular injections into the joint are also recommended. For severe cases, surgery may be the only option. A cunean tenectomy is done by cutting the cunean tendon to relieve pressure to the lower hock joints. Bone drilling can be performed to start new growth between the upper and lower bones of the joint. Chemical arthrodesis and laser arthrodesis may be done to destroy the cartilage and fuse the joint.
Other less common hock problems include chip fractures and carpal slab fractures. For chip fractures, arthroscopic surgery is recommended to stop the progression. Most carpal slab fractures are treated with lag screw fixation by drilling a hole in the slab and the bone, and inserting a screw.