Last Updated on February 25, 2022 by Allison Price
What does “fuse” mean to horse’s hocks?
A. To understand lameness in the hock we need to first understand the basic anatomy of the joint (or better, the joints).
Horse’s hock looks like an ankle. (Notice how it flexes in the same direction as humans’). It is composed of four joints: the Tarsocrural Joint (TSC), the Proximal Intertarsal Joint (PIT), The Distal Intertarsal Joint (DIT) and the Tarsometatarsal Joint (TMT).
We classify horses’ joints as high-motion and lowmotion. High-motion joints allow for a wide range of motion and can flex and expand. These joints include the carpus, stifle and fetlock as well as the TSC joint of hock. Low-motion joints on the other side have limited range of motion and serve mainly as shock absorbers. These are the pastern, lower two hock joints (DIT and TMT), and the pastern.
The most common causes of arthritic changes in horses are the DIT and TMT joints. Osteoarthritis is a condition that can be caused by performance or age, but it is always progressive. OA can cause cartilage damage, bone proliferation, and a narrowing of joint space. These conditions can lead to lameness.
Fusion is when severe OA causes bony proliferation, which makes the joints immobile. The decreased range of motion that causes fusion doesn’t affect the DIT or TMT joints. To effectively alleviate the pain of OA, however, the joint must be fully fused.
There are several ways to speed up the process. Your veterinarian may recommend a steroid injection to speed up the fusion process after diagnosing your horse’s lower hock OA. Your veterinarian may recommend ethyl Alcohol injections to help accelerate the fusion process. These injections are designed to completely destroy joint cartilage and promote fusion. Surgery is reserved for the most severely injured joints. These cases involve the horse being anesthetized and then the surgeon drilling away the cartilage to allow complete fusion.
Hock fusion is a great option for horses suffering from OA. It reduces pain and improves the horse’s quality life. It is often a painful and long process that can take years for the fusion to occur naturally. Consult your veterinarian if you have concerns about your horse’s hooves.
