Your horse is leaning on the bit, unwilling to bring his hind end up under himself or really use his hindquarters as he moves. When he takes a fence, he doesn't push off with the power you know he has. Is he getting lazy? Regressing in his training? Or is it hock problems?
The hocks are a key part of your horse's hind-end driving mechanism. Actions such as jumping and work at collected gaits, which call for extra hind-end effort, are especially tough on these hard-working joints. So are tight turns and small circles, which load the hocks unevenly and apply twisting force. With time and miles, the joints can start to break down and cause hock problems in horses.
That's the bad news—but there's good news, too. You can take steps to keep your horse working comfortably and extend his career, even when hock problems start to develop. In this article, we'll explain what goes wrong and what you can do.
Hocks, Healthy and Not
The hock links the bones of the lower leg (the cannon bone and the two splint bones alongside) to the tibia, in the upper leg—but it's not a simple joint. It's a complicated assembly of half a dozen bones, built to absorb shock, flex when the horse brings his hind legs under his body, and extend to propel him forward.
Most of the flexion and extension takes place in the upper part of the hock, in the tibiotarsal joint. The end of the tibia has a ridge, running front to back, that fits like the tip of a screwdriver into a groove on the squat, rounded bone below (the talus). Slick cartilage coats the working surfaces, and they slide back and forth along the groove as your horse flexes and extends the joint. Behind the talus, the largest hock bone juts up to form the point of the hock (calcaneus), which is roughly equivalent to your heel. It acts as a brace, preventing the joint from overextending.
Below the talus, two small flat bones (the third and central tarsals) are stacked like pancakes on top of the cannon. Other small bones sit behind and to the side, between the calcaneus and the cannon and splint bones. The joints in this lower (distal) part of the hock have limited range of motion. With thick pads of cartilage, they're built to absorb shock. Strong ligaments at the sides keep the whole assembly in line so the hock can't bend to the side—only front to back, like a hinge.
Problems in the hock joints tend to creep up gradually, and early signs can be subtle:
- Your horse may have an on-again off-again lameness, with or without noticeable heat or swelling.
- He may start out stiff but seem to "work out of it" as he warms up.
- He may resist going downhill or backing off the trailer.
- Muscles in his lower back may be sore from working overtime in an effort to spare his hocks.
Often the problem improves with rest but returns when he's back in regular work. Over time the soreness worsens. He takes short, stabbing strides behind or drags his hind toes.
A flexion test can make mild hock lameness easier to spot. For this, enlist a helper to ride or lead your horse. Stand at the hindquarters, facing back, and pick up the lower leg above the fetlock. Raise it as close as you can to the upper leg, flexing the hock, and hold it there for 60 seconds. Then put the foot down and tell your helper to immediately trot the horse straight away. If there's a hock problem, your horse will probably be markedly lamer for a number of strides.
These signs point to trouble, but they don't tell you what (or even exactly where) the problem is. Your veterinarian can do a full lameness exam, take X-rays and perform other tests to see what's going on.
The Prime Suspect: DJD
While several conditions can affect hock joints, for adult horses (especially performance horses) the problem is often degenerative joint disease (DJD), or arthritis. DJD typically develops in the lower joints of the hock, which come under a lot of stress when your horse works. Conformation can contribute. Flaws such as cow hocks and sickle hocks (see below) put uneven pressure on the joints. With upright "post-legged" conformation, the joints flex less to absorb shock, increasing impact and raising the risk of injury.
Within joints, injury or simple wear and tear can set off a destructive chain of events. The inner membrane of the joint, which produces the viscous fluid that fills the joint, becomes inflamed. The fluid, which lubricates the cartilage surfaces, becomes thin and watery. Cartilage is squeezed and starts to wear away, and lumps of new bone growth appear where bones are irritated. This commonly happens first at the inner aspect of the lower hock, where the small tarsal bones are compressed. Bone spavin, as this condition is called, often affects both hocks, but it's usually worse on one side.
Once bone spavin appears, it won't go away. But if you catch the degenerative spiral early, you may be able to manage the condition and slow its progression. The goal is to reduce inflammation in the joint, which in turn reduces pain and joint degeneration. What you do depends on how advanced the condition is, how sore your horse is and how demanding his work is.
Changes in his management and training program can help. Increase his turnout time, so he can move around at will. Cut back on the amount of intense work you do, especially work that stresses the hocks, and give him longer warm-ups. Light activity helps by improving circulation to the hock's soft tissues and by keeping joint fluid moving, which nourishes cartilage. Talk to your vet and farrier about shoeing changes—rockered toes, for instance, where the front part of the shoes are rolled up on an angle, help ease breakover behind. Sometimes it helps to increase hoof angle by raising the heel or shortening the toe. Avoid heel extensions, where the backs of the shoes are extended, and especially outside trailers, where the outside extension turns out. Extensions affect the path and landing of the foot, and that can put uneven pressure on the hocks.
If symptoms flare up, rest and cold hosing (or other cold therapy) can help. So can nonsteroidal anti-inflammatory drugs (NSAIDs) such as phenylbutazone. But soreness often returns when the horse goes back to work, and long-term treatment with NSAIDs may have harmful effects. There are better options, some new and some tried and true.
|Puffy hocks can be a sign of injury or of trouble brewing in the joint. But many soft-tissue swellings are not cause for alarm, especially if your horse isn't lame.