What the Hock Is and What it Does

Your horse’s hock is at once his most powerful and vulnerable joint. Do you know what it is and what it does?

This Hock and Joint article is part of our Joint and Hoof Health Awareness Month. Brought to you by Cosequin Joint Health Supplements.

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Your horse’s hock is at once his most powerful and vulnerable joint. A horse that can use his hocks well can run faster, jump higher, pull harder, and stop quicker. But if your horse’s hock is hurting, his performance potential plummets. And, unfortunately, because the it’s such a complex joint, there’s a lot that can go wrong. First, it’s important to understand what it is and how it works.

A horse that can use his hocks well, and therefore hindquarters, can run faster, jump higher, pull harder, and stop quicker.
A horse that can use his hocks well, and therefore hindquarters, can run faster, jump higher, pull harder, and stop quicker.
Photo by 42beats/stock.adobe.com

What Is The Hock

The hock, or tarsus, is the complex joint that allows quick locomotion and durability for your horse. This is the joint that allows the hind legs to quickly flex forward in the stride to prepare the quadriceps to powerfully propel him as the hocks extend. The anatomy of the hock is complex.

Tibio Tarsal Joint

To begin, the tibio tarsal joint is the highest joint and responsible for most of the movement. It’s lubricated by synovial fluid that’s produced and maintained by the articular cells that line the joint and protect the underlying bone. The synovial fluid is also responsible for absorbing concussion forces as the weight is distributed over the joints.

Proximal and Distal Intertarsal Joints

Next, there’s the proximal and distal intertarsal joints. It may share some of the synovial fluid in the higher joints. The lowest joint in the hock is the tarso metatarsal joint. This joint usually possesses its own joint fluid, which may not communicate with the others.

Durable Joint Capsule

The durable joint capsule suspends the joint fluid in each respective joint space. It’s important to have a good quality fluid in order for protection and efficiency. Although the lower three joints combined only account for 5% of the total motion, they’re responsible for a substantial amount of problems.

This complex joint is surrounded by a host of important blood vessels, ligaments, nerves, and tendons. There are no muscles around or below the hock in order for the tendonous structures to maneuver the distal limb. The digital flexor tendons pass through and over the inside and back part of the hock, and are critical in supporting your horse’s weight. The Achilles (gastrocnemius) tendon runs down the back of the limb above the hock and attaches on the point of the hock. If this tendon is cut, the whole function of the hock is lost, the hock folds, and a horse cannot support any weight.

Your horse is built so his stifle, hock, fetlock, and foot move in unison. This allows him to rest while one leg is locked. It’s also instrumental in his ability to create powerful, concentrated propulsion.

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