The hock is the angular joint on the back leg of a four-legged animal, sitting between the shin (tibia) and the foot. It’s the sharp, backward-pointing bend you can see roughly halfway down a dog’s hind leg or a horse’s hind leg. In human terms, the hock is the animal’s ankle, built from the same tarsal bones that form your own ankle joint.
Exact Location on the Hind Leg
Starting from the top of the hind leg and working down, the order goes: hip, stifle (the animal’s knee), then the hock, then the cannon bone (equivalent to the long bones in your foot), and finally the hoof or paw. The hock sits at the junction where the tibia and fibula meet the tarsal bones. In most animals, it’s the most visible joint on the hind leg because it creates a distinct angle that points backward, the opposite direction from the stifle above it.
On a dog, the hock is the sharp, bony bend partway up the back of the hind leg, well above the paw. Many people mistake it for the knee, but the actual knee (stifle) is higher up, often hidden under muscle and fur near the belly. On a horse, the hock is the large, complex joint about halfway between the hip and the hoof on the hind leg. On cattle, it sits in the same relative position and plays a key role in how the animal walks and bears weight.
Why It Looks Like a Backward Knee
The hock confuses people because it bends in the “wrong” direction compared to what we expect from a knee. But it isn’t a knee at all. It’s an ankle. Dogs, horses, and cattle are all walking on their toes (or the tips of their toes, in the case of hooved animals). What looks like the lower leg below the hock is actually the elongated foot. The real knee is tucked up near the animal’s body.
This toe-walking posture is what gives animals like greyhounds and horses their explosive speed. The hock acts like a spring-loaded hinge. Research on racing greyhounds found that the hock and hip joints produce the greatest increases in power during acceleration, making the hock critical for propulsion.
How to Find It on a Live Animal
On a dog, run your hand down the back of the hind leg from the thigh. You’ll feel a bony, angular joint that juts backward. That’s the hock. Below it, a long, straight section (the metatarsus) runs down to the paw. The joint itself feels firm and bony with little muscle covering it, which is why it’s prone to scrapes and pressure sores in larger breeds.
On a horse, the hock is even more prominent. You can feel a bony bump at the back of the joint, which is the point of the hock (the calcaneus, the same bone that forms your heel). On the inner side, there’s a noticeable bony ridge at the bottom of the tibia. If you flex the horse’s hind leg by lifting the lower limb, the stifle and hock flex together as a linked system, which is one of the easiest ways to see how the two joints work in tandem.
The Hock Across Different Species
The hock exists in virtually all four-legged mammals, though its proportions vary. In horses, it’s a large, complex joint made up of multiple small tarsal bones stacked together, allowing for both stability and the absorption of enormous forces during galloping and jumping. In dogs and cats, the hock is more compact but just as angular. Cats, being digitigrade (walking on their toes like dogs), have a very visible hock that gives their hind legs that characteristic zigzag shape.
In cattle, hock conformation matters enormously for long-term soundness. Ideally, when viewed from behind, a cow’s legs should be equally wide at the hocks and pasterns, with the animal walking straight forward and flexing cleanly at the hock. Cattle described as “sickle hocked” have an overly angled hock that pushes the feet too far under the body, straining the muscles and bones of the stifle and hip. On the other end, “post-legged” cattle have hocks that are too straight, reducing their ability to absorb shock.
Common Hock Problems
Because the hock bears so much force during movement, it’s a frequent site of injury and wear. In horses, most hock problems involve inflammation of the two lower joints within the hock complex. A horse with hock issues may show a firm swelling on the inner side of the joint, shortened stride, reluctance to work, or difficulty engaging the hind end. Bone spavin, a form of arthritis in these lower hock joints, is one of the most common causes of hind-limb lameness in working and sport horses.
In dogs, hock injuries often involve sprains of the supporting ligaments or, in more serious cases, hyperextension where the joint collapses forward. Large and giant breeds are also prone to “capped hock,” a fluid-filled swelling on the point of the hock caused by repeatedly lying on hard surfaces. In cattle, poor hock conformation contributes to lameness over time, which is why livestock evaluators pay close attention to hock angle and leg structure when assessing breeding animals. The ideal hind-leg setup includes a roughly 45-degree angle at the pastern joint below the hock, with toes pointing straight ahead.