The Hock Question

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Sometimes it starts with a strange sign: Not wanting to perform a flying lead change, sudden laziness, difficulty engaging the hind end, not wanting to be tacked up, and any general cranky behavior in a previously content horse. As the trainer it’s your job to help your client figure out why the horse has had a sudden change of heart. Often, after talking to a vet, hock issues are suspected, and hock injections are a possible solution.

The hock is a very complex joint, and it’s not always easy to identify it as the source of the problem. Veterinarians need to take information from as many areas as possible. Dr. Chris Kawcak DMV, PhD, associate professor at Colorado State University, believes there are many trainers out there who can “feel a problem” in the hind end. “Trainers can play a big part in figuring out where a horse is sore,” he says. Dr. Steve Kloepfer DMV of Alpine Equine Services in Longmont, Colo., agrees that “information from trainers and riders is helpful” in distinguishing where to look for the source of the problem.

The signs of sore hocks can be as vague as ‘poor performance’ or ‘strange habits under saddle.’ There’s a lot of gray area,” says Kloepfer. Other times the signs are much more disruptive, such as bucking, refusing to jump, bolting or charging jumps, which, Kloepfer adds, “can be a way of running away from the pain.”

Often, sore hocks show up as horses “not performing up to their potential. When it becomes consistent and impedes the horse’s ability to work,” says Kawcak, that’s a common sign of hock pain.

Still, there are much more methodical and exhaustive ways of discerning whether the hock is the culprit. Being thorough is paramount to a proper diagnosis. Simple flexion tests are not going to give you enough information.

Dr. Lisa A. Fortier, DVM, PhD, Diplomate ACVS at Cornell University, strongly recommends a “full lameness exam,” including flexion tests to help pinpoint the limb or limbs in question, as well as “blocking the joints with a local anesthetic” to further pinpoint the problematic joint. Fortier also finds radiographs and MRIs to be helpful tools in discovering what is going on inside a joint.

The Culprit: Arthritis

What we are really talking about when confronted with joint pain is arthritis, which is very common in performance horses. As Kloepfer puts it, “arthritis is chronic ‘wear and tear’ disease. Constant work prevents the body from having time to heal the joint before developing the arthritis.”

The hock joint has to deal with constant friction and strain, or “long term, low-grade trauma due to exercise,” as Kawcak puts it. Due to the “low-grade trauma,” the joint becomes irritated and the joint capsule becomes inflamed. That inflammation is what causes the pain.

The Injection Solution

Once the hock problem is diagnosed, hock injections are frequently the solution. When a veterinarian injects horses’ hocks, the injection typically consists of a steroid and HA (Hyaluronic Acid). HA is naturally found in the synovial fluid inside the joint capsule, and it plays a role in maintaining the viscosity of the fluid, which keeps the joint functioning smoothly. Both the steroid and HA will act as anti-inflammatories; taking away the inflammation takes away the pain. Both can also “stop or slow down the cyclical process of arthritis,” Fortier says. Kloepfer adds, “HA can stimulate the synovial membrane and synovial fluid, as well as act as a barrier protectant” inside the joint capsule.

How well do hock injections work? Kawcak holds that “if diagnosed appropriately, hock injections are very effective, and the prognosis is excellent.” Kloepfer agrees, saying that “on a performance horse with suspicion of problematic hocks, if they have never been injected and are in work, almost 100 percent benefit,” in one way or another.

In evaluating the success rate of hock injections, it’s important to look at the horse’s workload. The first set of injections for a grand prix-level dressage horse will most likely not last as long as they would for a horse who is asked to perform considerably less demanding work. A harder-working horse may require more constant assessment, and possibly more frequent injections, Kawcak says. The long-term success of hock injections greatly depends on the expectations placed on the horse.

Hock injections are not a panacea. “There are cases where injecting the hocks will not work,” Kloepfer says. “The hocks may only be part of the problem.

They are usually the most critical point of pain in the hind end, but your average horse is sore in more than one place. Sore, not necessarily lame.”

He advises that it is important to prepare clients for a “long haul.” Injecting the hocks may be only the first part of “un-muddying the waters,” as he put it. Kawcak has found in working on cutting horses that, once the hocks have been treated, the suspensory tendon would sometimes show up as a secondary problem.

Fortier and Kawcak both have found that a sore back can occur in conjunction with sore hocks. Horses typically compensate for pain in one area by over-using another part of their bodies, and the back is one of the parts that can become stressed. Kawcak has had good results using a chiropractor after the hocks have been injected; this gives the chiropractor a better chance of being effective in unlocking the back and pelvis.

Kawcak has also observed that jumpers and eventers with sore hocks will compensate by bearing more weight on their front ends, which can in turn make front joints sore as well. Where this is the case, the original lameness exam may not show the front-end lameness, because it was less severe than in the hind end. However once the hind end is comfortable, front end lameness can suddenly become visible. Fortunately, fixing the sore hocks can provide much-needed relief to other parts of the body.

One other caution: Hock injections may make little difference in rare cases where the bone loss or bone changes are too severe for any treatment to make a difference.

The Recovery Period

Now that the horse has had the injections, and all is hopeful, how about going back to work? Fortier recommends active rest, such as turnout, for a couple days, “to make sure there is no infection in the injection site, then back to mild exercise such as long and low stretching work.” She discourages stall rest, as it can create more stiffness.

Kawcak and Kloepfer agree: both feel it is important to keep the horse moving. Kawcak advises three days of rest, and for horses who live in stalls to be “hand walked for at least 15 minutes twice a day for all three days.” He also says that it is important to monitor the horse when going back to work, to “start slowly and see what you get.”

Kloepfer tailors the rest to what was actually injected into the joint and how much time he feels is adequate to start the healing process. When he injects HA by itself, his protocol calls for three days rest. If a short-acting steroid is used with the HA, then he prefers four days rest. If a long acting steroid is used, the rest period stretches to two weeks. In this last instance, Kloepfer encourages riding at the walk after the first three days to keep the horse moving.

The time it may take to identify and treat a horse with hock pain may seem tedious, but the payoff is a happy, pain-free horse that can return to being the working athlete he was born to be. And that makes it all worthwhile. Kloepfer lays it out very simply when he says, “there are probably hundreds of thousands of owners who, had they known all the horse needed was a joint injection, wouldn’t have gotten rid of the horse.” Don’t be one of them!