Hock Injections: A Sound Practice?

This procedure is common in dressage horses. For some, it’s routine “maintenance.” Should it be?

By Sarah Evers Conrad

Reprinted from the September 2018 USDF Connection magazine

If only our horses could talk and tell us where it hurts, we’d no longer have to guess what might be causing them to feel “off” when we ride, or why those frustrating performance problems have started happening. But over time we learn which parts of the horse’s body are prone to wear and tear—and because of the demands that dressage places on the horse’s hindquarter joints, for many riders and horse owners, the hocks wind up being the usual suspects.

The stresses of athletic performance can lead to inflammation and osteoarthritis (OA) in the hock joints. To combat the resulting stiffness and pain, some horse owners routinely have the joints injected, usually with steroids or other anti-inflammatories, with substances designed to improve joint function, or with some combination of these.

No joint injection is risk-free, however, and not all experts are on board with the idea of regularly scheduled hock injections as “maintenance.” For this article, we asked two well-known sport-horse veterinarians to explain the benefits and potential drawbacks of hock injections, as well as for guidance in determining when—or if—they might help your horse feel and perform better.

Not One Joint but Four

That’s right: There’s not just one “hock joint.” The horse’s hock (the tarsus, in veterinary terms) consists of four joints, any one (or more) of which may be a source of discomfort.

The tarsocrural joint, a high-motion joint at the top of the hock, is the largest joint in the hock (see illustration below). From top to bottom, the three smaller joints are the proximal intertarsal joint, the distal intertarsal joint, and the tarsal-metatarsal joint. These smaller joints are considered low-motion joints.

Despite the fact that the smaller joints don’t move much, most hock OA is found in the lower two hock joints—the distal intertarsal and the tarsal-metatarsal—says Rick Mitchell, DVM, MRCVS, Dipl. ACVSMR, of Fairfield Equine Associates, Newtown, CT.

“Other issues may occur related to collateral and intertarsal ligament strain that may also lead to discomfort and/or arthritic changes,” Mitchell adds.

Issues in the tarsocrural joint, also known as the tibio-tarsal joint, can include osteochondritis dissecans (OCD) lesions, which produce inflammation and soreness related to developing synovitis; and fluid swelling (“bog spavin”), Mitchell says.

Diagnosing Hock Problems

Hock issues can run the gamut: from so slight that it’s just a feeling that the horse is off, to noticeable inflammation, radiographic changes, a positive flexion test during a lameness exam, or some combination of the latter, says Jack Snyder, DVM, PhD, Dipl. ACVS, an international sport-horse veterinarian based out of Circle Oak Equine, Petaluma, CA. Like Mitchell, Snyder is a former US Equestrian Team veterinarian, caring for US horses at Olympic Games, World Equestrian Games, and other major championships.

Although changes on hock radiographs tend to worry horse owners, Snyder says that hock disease does not always match the pictures.

“You can have horrible x-ray changes, and the horse is fine,” he says, “and vice versa: where you can have very little changes or no changes, and it’s bothering the horse.”

That’s part of the reason a thorough lameness examination is step 1 in addressing any suspected hock issue, Mitchell says. Before your veterinarian can discuss treatment options, the source of the discomfort must be pinpointed.

Hock Injections Explained

If a lameness examination indicates that your horse indeed is experiencing discomfort in one or more hock joints, your veterinarian may recommend proceeding with the injection process.

There is an array of products that can be injected into the space between one or more affected hock joints (called an intra-articular, or IA, injection). Current options include:

Corticosteroids, which have powerful anti-inflammatory properties

Polysulfated glycosaminoglycan, or PSGAG (Adequan® IA), to help stimulate cartilage repair, restore synovial lubrication, and inhibit enzymes that attack cartilage and synovial fluid. Mitchell favors Adequan® IM, which is injected into the muscle.

Hyaluronic acid/sodium hyaluronate (Legend), an important component of synovial fluid, which cushions the joints

Biologics (substances created by the horse’s own body), such as interleukin-1 receptor antagonist protein (IRAP); platelet-rich plasma (PRP); and a system called Pro-Stride Autologous Protein Solution, which contains a concentrated solution of cells, platelets, growth factors, and anti-inflammatory proteins, including IRAP.

“Generally, the substances injected reduce inflammation and allow the joint environment to assume a more normal state and level of function, producing better-quality joint fluid and providing essential nourishment and lubrication to articular cartilage,” Mitchell explains.

Of the options, steroids have the most potent anti-inflammatory effect, according to Snyder. Accordingly, steroids are often his go-to for OA in the low-motion joints. But steroid use has its risks (which we’ll discuss in a minute); so if a horse has OA in a high-motion joint or if it needs the same joint injected multiple times, Snyder might switch to a different agent following a treatment with steroids.

Timing Issues

Your horse may show improvement as soon as 24 to 48 hours post-injection, Snyder says. But don’t be too eager to get on and ride, he cautions: Most veterinarians suggest resting a horse for one to three days after the procedure.

“What you want is for the agent that you are using to have its maximum effect before you start stimulating it again,” Snyder explains. “If I have the time, I give the horse two days off and on the third day, ride light. Shortening that up doesn’t have a negative or detrimental effect, but maybe your treatment won’t be as effective or last as long.”

Snyder recommends not having joint injections done right before you transport your horse, because it’s harder to monitor him or to deal with any post-injection issues while on the road.

Another thing he tries to avoid is injecting all of the hock joints, unless they all have a problem. In general, he sticks to the bottom two joints (the distal intertarsal and the tarsal-metatarsal), saying that these two usually produce the best results.
Neither Snyder nor Mitchell is a fan of injecting joints as a routine or “maintenance” procedure.

“Simply injecting a joint because the schedule suggests it is indicated is not sound practice,” Mitchell says. Instead, have your veterinarian evaluate your horse periodically and address any issues if they arise, he recommends.

In striving to achieve the maximum benefit from joint injections, there may be a sweet spot—somewhere between needlessly injecting the young, sound horse and waiting until the equine athlete is showing signs of marked discomfort.

“You don’t want to wait too long in [treating] any joint because then you’re fighting the disease process,” says Snyder.

Joint injections aren’t inexpensive. The good news is that, depending on the horse, it may be a long time before you need to repeat the procedure.

According to Snyder, some five- to seven-year-olds need only one injection to arrest the inflammatory process, and they may not need a follow-up injection for years. However, other horses—especially older ones—may benefit from yearly injections or even more frequently. Because every horse is different, Snyder stresses the importance of having a veterinarian regularly monitor your horse over time. And for benchmarking purposes, take note of when your horse gets his hocks “done” as well as how long the effects last, Mitchell recommends.

Risks

One of the biggest risks in injecting any joint is infection. No matter how skilled a veterinarian is at giving IA injections, and no matter how well the injection site is cleaned and prepped, the risk of infection cannot be eliminated because the needle will always carry some foreign material—skin, debris, and bacteria—into the joint, Snyder says. Injecting steroids increases the risk because steroids reduce the immune system’s response and thus the horse’s ability to fight infection.

Post-injection joint infection is not common, but when it happens it is a life-threatening emergency that needs immediate treatment, Snyder stresses. Infection doesn’t set in immediately: When it occurs, it may manifest anywhere from five to 14 days post-procedure, and sometimes as long as 30 days afterward, he says.

Snyder warns against overuse of steroids in general, especially in high-motion joints.

“If you use steroids over and over again in a high-motion joint,” he says, “it will lead to degradation or breakdown of the cartilage.” Cartilage cushions the joints, and so its breakdown can worsen joint disease, he explains.

Biologic products carry less infection risk because they don’t depress the immune system. “The other positive of the other agents is that you don’t have any drug-testing time because you’re actually using products from the horse’s body,” says Snyder, referring to the official drugs and medications regulations imposed by equestrian sports’ national and international governing bodies.

Another joint-injection risk factor is an inflammatory response, often referred to as a joint flare or reaction, which can cause lameness. The condition usually appears 24 to 48 hours after treatment. Obviously, more inflammation is the last thing one wants to see after hock injections, but fortunately this reaction is also rare, Snyder says.

Another very unwanted potential side effect of injecting a joint with steroids is laminitis, which like infection can be life-threatening.

“That’s another reason not to be indiscriminately putting steroids in a horse,” says Snyder, “because all of a sudden you have a horse you didn’t have any problems with, and you treat its joints with steroids, and the next thing you have the horse foundering.”

Citing an increased risk of laminitis, Mitchell advises against performing corticosteroid joint injections on horses with metabolic issues, such as equine metabolic syndrome (EMS) or pituitary pars intermedia dysfunction (PPID, aka equine Cushing’s disease). With such horses, he suggests IRAP or Pro-Stride instead.

By now you might be terrified of ever putting steroids in your horse’s joints, but in fact steroids remain Snyder’s usual first choice for the low-motion joints, either alone or with hyaluronic acid, because they have the strongest anti-inflammatory effect. In addition, they are often less expensive than the biologic products, he says. But if steroids aren’t producing the hoped-for benefits, Snyder may turn to the Pro-Stride system or IRAP, he says.

Healthier Joints, Naturally

One way to reduce the need for joint injections and to improve joint health in the dressage horse is to turn him out as much as possible.

“The more the horse is moving around, the [fewer joint-related] issues you’re going to deal with,” says Snyder.

Unfortunately, turnout usually isn’t an option at shows, and not all stables have adequate paddocks or pasture land. If this is the case for your horse, then the warm-up phase of your rides becomes even more important, Snyder says. Make your warm-ups long and gradual enough to allow your horse’s joints to get loose and “oiled” before you ask for harder work.

For those who don’t want to do hock injections, there are other, noninvasive ways of managing OA-related inflammation and discomfort. Various nonsteroidal anti-inflammatory drugs (NSAIDs) may offer relief. A glance at most any equestrian retailer’s website or vet-supply catalog reveals an array of oral “nutraceutical” supplements that target joint health (Mitchell says that supplements containing resveratrol, the anti-inflammatory substance found in red wine and red grape juice, may be beneficial). Physical-therapy modalities, such as extracorporeal shockwave, Class IV laser, and pulsed electromagnetic field (PEMF) therapy, also may help some horses, Mitchell says.

Effectiveness of any treatment depends on the disease progression and on how long the horse has been symptomatic, says Snyder, so discuss options with your veterinarian—especially if you wish to compete, as some substances and modalities are restricted or prohibited.

When More Aren’t Better

“Like many other medical treatments, joint injections are good for the horse if done responsibly and with a reasonable diagnostic effort on the part of the veterinarian,” says Mitchell. But if you find that your horse needs increasingly frequent hock injections just to keep performing, then it may be time to reconsider, he says.

“The need for frequent injections bears out the need for a reassessment of the therapy being used,” he says. “Perhaps a different therapeutic approach, such as choice of medication or other agent, is needed; or reevaluation of the true problem may be indicated.”

You, your veterinarian, and your instructor/trainer are part of your horse’s team. Your goal: a healthy, happy horse that can comfortably manage the demands of dressage. Veterinary medicine has made remarkable advances in diagnosing and treating disease, but good horsemanship and thoughtful management remain the cornerstones for keeping our horses healthy.

Fusion: A Last Resort

If hock injections of any kind are no longer reducing your horse’s inflammation and pain, then your veterinarian may recommend fusing the involved joints in order to stabilize the area.

Injecting the joint with alcohol is one method of causing it to fuse, says Jack Snyder, DVM, PhD, Dipl. ACVS, of Circle Oak Equine, Petaluma, CA. The other is surgery, using a laser or a surgical drill, he says. In either method, the goal is to cause a reaction that will help the horse’s body to lay down bone so that the joint stabilizes, thereby eliminating the pain caused by movement.

Sarah Evers Conrad, of Lexington, KY, is a journalist, editor of the Certified Horsemanship Association’s The Instructor magazine, and a digital marketer. She has been a staffer at The Horse magazine and at US Equestrian’s Equestrian magazine before serving as US Equestrian’s director of e-communications. Now as owner of All in Stride Marketing, she helps small businesses with their marketing and content needs in addition to writing for publications.