Joint Injuries In Horses
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By Heather Smith Thomas
Photos courtesy Dr. Duncan Peters
Athletic horses in strenuous careers often suffer injury. Young horses in training are also frequently injured when too much stress and strain is placed on immature joints. Western performance horses are at risk for several types of joint injuries because of the stress and strain on limbs when sprinting, stopping quickly, turning and spinning off in another direction. Hunter-jumpers are at risk for injuries related to jumping. Every discipline has its own set of common injuries.
COMMON JOINT INJURIES
Dr. Duncan Peters (College of Veterinary Medicine, Equine Lameness and Sports Medicine Program, Michigan State University) says some of the most common joint injuries involve front ankles (fetlock joints) and hocks. “These joints take a lot of strain in several types of athletic maneuvers. In the front ankles we sometimes see acute joint injuries and little chip fragments if horses hyperextend those joints when jumping or put a lot of force into stopping and turning. We also see sprains in ankle joints, and over time we tend to see a lot of arthritis in these joints. This would include bone spurs around the edges of the joints,” says Peters.
“The hock is another site we see joint problems, especially in the lower joints of the hock. These joints are stressed during twisting and torque on the leg during turns and stops. The hock joints are strong, and pretty good at handling high load/low motion action but unfortunately they do get sore. We try to make sure the shoeing is very good, to put the least stress on the leg as it twists,” he says.
“Other common injuries occur in the stifles in the hind legs and coffin joints in the front foot. The stifle is built like the human knee. Stopping and turning and pushing off at full speed again puts a lot of stress on stifles. The stifles are very important in this action, and can become sprained or develop ligament injuries or tear the meniscus.” If stifles get sore, the horse won’t want to stop and turn.
Also stressed are coffin joints in the front feet during fast turns or any speed events. “If the horse plants the front feet and rotates, collateral ligaments at the front of the coffin bone take the brunt of that stress and rotation. Direct concussion in the cartilage of the joint itself can also be a factor as the foot is jammed into the ground,” says Peters.
Similarly, the pastern joint (between coffin bone and short pastern bone directly above it) can be strained, though it’s not as common for this joint to be injured. “If it does get strained, we may see ringbone-type changes in that area. This would develop over a longer time, in an older horse—with repeated twisting and concussion. Your veterinarian might look at radiographs taken for some other purpose and notice some ringbone. Over time, stress takes a toll, and it may or may not make the horse sore. This is another high load, low motion joint, similar to the lower joints of the hocks.” There’s not a lot of movement in the pastern joint, but there is a little—which is important for the rotational aspect of the horse’s action in fast turns.
Simple concussion can also lead to joint injuries if a horse is used hard, or does a lot of work on hard surfaces.
TREATMENTS
Today there are dozens of treatments for joint problems. Some are therapeutic, aimed at helping an injured joint heal or to minimize pain and inflammation within a diseased joint, while others are prophylactic, to try to prevent joint injury and damage.
Some injuries need a specific treatment or surgical intervention. “With an acute chip fracture/fragment in the front ankles, we have to remove those surgically,” says Peters. “After that we would try to protect that joint as much as possible, using things like joint supplements and injections like HA (hyaluronic acid) and Adequan®, etc. We are trying to guard against and minimize secondary arthritic changes on down the road. For things like sprains and strains, the horse will need rest from work. We may also give injections like HA, and sometimes steroids,” he says.
INJECTIONS
Most athletic horses with joint problems are treated with a combination of steroids and HA or either one of these by themselves—injected directly into the joint. Many people mix them together when trying to treat an inflammatory problem within the joint.
Other protective-type drugs can be injected into the muscle, or given intravenously. These include Adequan® (a polysulfated glycosaminoglycan, or PSGAG), and HA (usually Legend®). Adequan® can be injected either into the muscle or directly into the joint. Some studies have shown that it’s more potent and protective when used in the joint rather than injected into muscle. This product is often used after joint surgery because it seems to reduce the amount of scar tissue in the joint capsule and soft tissues surrounding the joint.
Some veterinarians use steroids in joints. Corticosteroids have been shown to help the cartilage by minimizing inflammation that is detrimental to cartilage health. This is similar to a person with a bad shoulder or elbow. Often the doctor will inject cortisone to alleviate inflammation.
Some veterinarians try different combinations of steroids including some that are short-acting and some long-acting. Dr. David Frisbie, Associate Professor in Surgery at the Orthopedic Research Center at Colorado State University and partner in Equine Sports Medicine, Pilot Point, Texas, says corticosteroids are still the mainstay in joint treatment. “These have been in use since the 1950s and are still probably the best medication we have, in many ways. There are basically 3 common steroids used. They all reduce inflammation, but one of them (triamcinolone acetonide, trade name Vetalog®) has been shown to be protective to joints with arthritis. Some steroids, even though they reduce inflammation, can be detrimental to the tissue,” he says. There are a few contraindications for steroid use, such as in horses that have a metabolic disturbance and/or are old or have Cushings syndrome or previous laminitis.
Many people mix steroids and HA together when they do a joint injection. There is evidence that the combination has an added beneficial effect since HA is a natural lubricant. Some people just use straight HA or just a steroid in the joint. “The people using just HA would be a small minority, since potency of that particular drug alone is low. There are a few specific indications, such as following surgery, however, where this might be appropriate, using HA without the steroids,” he says.
Another drug called Polyglycan® is a combination of chondroitin sulfate, glucosamine and hyaluronic acid. Other things that may be beneficial for joints include intravenous products. “The only licensed intravenous HA product is Legend®. It’s being used for treating joint disease, and there is some potential for a prophylactic effect as well. The standard procedure is three treatments if you are treating a disease, or giving it once or twice a month if using it as a prophylactic to try to keep a joint healthy,” says Frisbie.
REGENRATIVE THERAPIES
Peters says some horse owners ask their veterinarian to try regenerative medicine strategies. “This might involve something like IRAP (interleuken receptor antagonist protein) or PRP (platelet-rich plasma). Those are the main ones we’d use for a sprain or strain to help it heal more quickly. This would help quiet down and minimize inflammation and help the healing by adding growth factors,” explains Peters.
There are several ways of creating IRAP. “The gene sequence for that protein can be put into a virus, fooling the virus into making the protein in the joint for us,” says Frisbie. “This is one of the few therapies that’s actually been shown to be more effective and more protective than corticosteroids. The problem is that it’s basically a one-time shot. It is very effective once.” After that, the body builds resistance to the virus, just as humans develop resistance to a cold virus after experiencing a cold. This defense process does not allow the treatment to work a second time.
“The other way to make the protein is to take whole blood from the horse and use some of the white blood cells, which when stimulated in a certain way increase their concentration of that particular protein. This is a treatment you can repeat, even though the concentration if IRAP is not nearly as high. It is still effective in treating joint disease,” says Frisbie.
The IRAP treatment is usually one injection weekly, for 3 weeks. “You have to pull blood, culture it, then get the product and inject it 3 separate times. By the time you are finished, it’s a lot more expensive than the steroid injections. But there are cases where steroids don’t work and the IRAP does work,” he says.
“In our practice, we tend to reserve it for cases that are non-responsive to steroids, or for a surgery case where you don’t want to put steroids into the joint because steroids diminish the immune response. So we use the IRAP instead,” says Frisbie.
There is a tremendous move today in performance horse and racing industries toward using biological, natural regenerative therapies like IRAP, PRP or stem cells. “I think these types of treatment will be the wave of the future, with people using something the horse’s own body can utilize in a repair process—or something that will stimulate the body to take care of a problem,” says Peters.
“We don’t entirely know how those things work because we haven’t done a lot of cases. With IRAP, we know it will block the inflammatory cascade, but with the PRP or the stem cells we are not quite sure how those are working in the joints. We don’t know if they are actively doing the repair themselves or if they are stimulating other aspects of the process,” he says.
“Cytokines, chemical reactors and chemical mediators, growth factors and individual cells within the joint may be stimulated or up-regulated to produce other growth factors or other positive compounds. We don’t know if these therapies do other things to result in reduced inflammation. There is a lot of research being done in this area, and these therapies may be used more in the future because of their ability to heal joints and maintain joints,” says Peters.
The “maintenance” injections many people were using with HA and steroids have fallen out of favor a little because of potentially detrimental effects of the steroids. “Now, more people are trying to treat a specific joint for a specific problem. This is probably where the biological regenerative therapies will be helpful,” says Peters.
“You can get the benefit of quieting down inflammation or maintaining the joint without the risks associated with steroids—such as cartilage breakdown over time, or the possibility of laminitis,” he says.
“We are still learning about some of the newer therapies. We have a much better handle on the HA or Adequan® in joints, and the cortiocosteroids, and it will just take some time, as we use the newer treatments, to get a better feel for when they work best, or what types of things they work the best on. There is a lot of basic science being done, as well as clinical-use science going on right now, involving these new treatments, and I foresee more use of these in the future,” says Peters.
REST and REHAB, COLD THERAPY,
and ADJUNCTIVE THERAPIES
Along with treatment, the horse needs rest, and physical therapy to help an injured joint heal optimally and get back to full strength. Cold therapy and bandaging may help initially, to reduce inflammation and swelling. Bandaging by itself (for a short period of time) can help reduce initial inflammation by stabilizing the joint and minimizing movement. Topical products like DMSO can also help reduce pain and inflammation.
“The biggest thing that hurts those joints is chronic inflammation. If you can get that under control, this can go a long way toward minimizing arthritic changes and more bone formation,” says Peters.
The rest period required may vary with the horse and the injury—and how severe it is. The horse owner should consult with a veterinarian to figure out the best treatment and recovery program, and possible physical therapy. “This involves some close monitoring and observing how the horse responds to treatment,” he says.
Most people want to get the horse back to work and competing again as soon as possible, so it is imperative to do the best for that horse to help it heal—which means a certain period of rest. “Just like a person, if we sprain an ankle, the time frame for staying off it would be 1 to 2 weeks, and then start gradually putting weight on it, and not overdo it until it’s healed,” says Peters.
People still use ice and anti-inflammatories such as phenylbutazone, Banamine®, Equioxx®, etc. to help to shut down the inflammation. Cold water therapy, saltwater, etc. tend to relieve pain and inflammation. “These would help pull out edema, which helps with blood flow, which helps reduce inflammation,” says Frisbie. “Those are all good, but might be most helpful when used in conjunction with other treatments.
Some adjunctive therapies being used for joint injuries include things like cold saltwater spas, electromagnetic therapy, laser therapy, therapeutic ultrasound, etc. The most potent adjunctive therapy that Frisbie feels is most effective is shock wave therapy. “That has been shown to be significantly beneficial in joint related problems.”
NSAIDs
“The nonsteroidal anti-inflammatories (NSAIDs) are good for short term use, like a 2-week period,” says Frisbie. “These can help a soft tissue injury such as a pulled ligament, or a flare-up of an old injury. Bute, Banamine®, naproxine, etc. can be a good short-term fix,” says Frisbie.
“There is also a relatively new product that works fairly well. There are some good and bad inflammatory cascades that result from injury. COX2 is thought to be the bad one we want to inhibit. Celebrex® and all of the newer human drugs are COX2 inhibitors. There is now a COX2 inhibitor for the horse, called Equioxx®. For joint-related issues we tend to use it, rather than bute, Banamine®, etc. There is still a place for those, but from a GI tract side-effects standpoint (ulcers), Equioxx® would be safer to use, especially longer-term,” he says.
Another drug, called sodium diclofenac (Surpass®) is also in the non-steroidal class, but is used topically. “If you have a solitary joint injury, this drug works really well on the soft tissues. We did a study where we showed it could actually protect the joint or decrease the progression of arthritis,” he says.
ORAL SUPPLEMENTS
There are many oral supplements for horses but most of them have not been put through clinical trials to know whether they really work to keep joints healthy. The main ingredients for most of these are glucosamine, chondroitin, or hyaluronate—a salt derivative of HA. Many products contain those ingredients, including Cosequin®, Cortaflex®, Hyaluron®, Lubrisyn®, etc. These are termed nutraceuticals, which are nutrients designed to have a pharmaceutical affect. They are not regulated, so their efficacy is questionable.
Another type of product that seems to have some benefit for cartilage health is cetyl-myristoleate. The trade names are Cetyl-M® and Myristol®. MSM (methylsulfonylmethane) is another neutraceutical often included in joint supplement products, and probably the one that’s been used the longest. This organic compound derived from DMSO (dimethyl sulfoxide) provides a dietary source of bio-available sulfur, one of the elements essential to formation of connective tissue. It seems to help relieve the pain of arthritis.
There are several ‘natural’ products, such as herbs or homeopathic products that some people use for joint treatment, such as Devils Claw, and Zeel. Whether or not they work, we don’t know.
“The important thing with any treatment is to consider the potency, and the relationship of potency to cost,” says Frisbie. “Some treatments are a lot more potent than others. If you are using something that isn’t very potent but costs a lot, it may not make sense to use it. Most oral medication/supplements fall into that category. An exception is ASU (avocado/soybean unsaponifiables). Oil from soybeans and avocados (the part that can’t be used for making soap) is used as an oral supplement. Work in the lab, and clinical trials in people, have shown this supplement is effective. We recently tested it in the horse and have shown it to be effective in arthritis. We’ve tested oral HA products, with less than significant results,” says Frisbie.
“In the end you have to decide if you are getting the biggest bang for the buck. Oral products probably aren’t that great a deal unless you are actually getting some prophylactic benefit. We tell people that if they want to do something prophylactic, IV Legend® once or twice or month is probably helpful. If they want to do more than that, we recommend they use an oral product containing ASU. But none of that would be as good as treating the joint directly, if the horse is actually sore,” explains Frisbie.
