Veterinarians debate the pros and cons of oral supplements and different types of injections for care of working equine joints.
It’s a simple fact of life that an equine athlete’s joints deteriorate. The hind legs that once effortlessly coiled at the base of a jump, propelling the horse and rider high in the air, lose their flexibility and power. The swinging, ground-covering trot eventually lacks its former brilliance.
A lame horse with a hot, swollen joint is the textbook example of joint disease, but the process is a degenerative one that begins and has effects well before the end result of heat, swelling and lameness. Degenerative joint disease, or osteoarthritis, is a relentless enemy that begins his march stealthily and quietly, laying the groundwork for debilitating effects in the future.
Walk down the aisle of any tack store or flip through the pages of any horse magazine, and you’ll be astounded at the number of products on the market that claim to stem the tide of joint disease.
You can choose from a veritable cornucopia of oral joint supplements for your horse. You can administer injected systemic medications such as Legend or Adequan or treat the joint directly with intra-articular injections, delivering medicines directly into the joint capsule.
But how do you know where to begin, and how do you approach the insidious enemy, joint disease? What’s the best way to reinforce your horse’s joints against his onslaught?
The best way to think about the three routes of delivery of medication—oral, parenteral (intravenous or intramuscular) injections, or intra-articular injections—is to realize that their potency somewhat increases the more targeted their delivery.
“If you rate them on a scale of 1 to 10, with 10 the best and 1 barely working at all, intra-articular medications as a class would be the 10,” said David Frisbie, DVM and Ph.D. of Colorado State University’s Equine Orthopaedic Research Center. “Parenterals would be at a 4 or a 5, with oral supplements coming in between 1 and 3.”
While delivering medication via intra-articular injections is the gold standard of treating joint disease, oral supplements and parenteral medications such as Adequan and Legend have a place in the battle as well.
“The answer to me is that if oral supplements don’t make a difference, I think you need to look farther and maybe consider an injectible medication. And then if that’s not working, you need to look farther and make sure there’s not a lameness that needs to be treated,” said Richard Markell, DVM, of Ranch and Coast Equine Practice in Encinitas, Calif.
“Unfortunately, nobody definitively has any of the answers. There really is no solid research that tells you the answers to these questions. I think that’s why, if you talk to 20 different veterinarians, they’re going to have 20 different opinions on this subject,” Markell continued.
Locate The Problem
The most important step in managing a horse’s joint disease isn’t choosing between different therapies. It’s pinpointing the exact problem.
“An accurate diagnosis is the cornerstone to an effective treatment,” said Markell. “You can spend a lot of money on supplements and joint therapy and waste a lot of time during which the joint disease is progressing, when you should have had an accurate diagnosis in the first place.”
The strain of repeated extreme effort takes a toll on the synovial fluid and cartilage that are essential to a healthy joint environment. The “wear and tear” on a joint is an active disease process: osteoarthritis.
In osteoarthritis, the normal rebuilding of cartilage in the joint becomes outpaced by cartilage degradation, resulting in the cartilage becoming thin and damaged, which causes inflammation. The synovial fluid in the joint also becomes less viscous and loses its lubricating ability as joint disease progresses.
Marked lameness, especially with heat and swelling evident in a joint, is the most obvious symptom of joint disease. But horses can indicate that their joints are inflamed and causing problems well before overt lameness develops. A reluctance to change leads or perform collected work might be a sign that joint disease is compromising your horse’s performance.
“Part of the problem is that horses can’t tell us which joint hurts, and for mild joint disease, the joint doesn’t swell excessively, so people often don’t realize that what seems to be a more generalized problem is actually one particular joint,” said Frisbie.
“If you have a training issue in a performance horse, absolutely the first thing you need to do is to rule out a medical basis for the training issue. Is he not changing leads because he has a sore sacroiliac joint? Or is he resistant to piaffe because his neck hurts?” Markell said.
“Not every orthopedic issue is a limping horse. Most horses want to do what you’re asking. If they don’t want to do it, you have to investigate the possibility of a medical issue. And an accurate diagnosis is key to pinpointing the problem,” Markell continued.
Oral Supplements: Part Of Management
Hundreds of oral joint supplements on the market claim to slow the progression of joint disease. They incorporate various ingredients to decrease inflammation and maintain a healthy joint environment. But they’re limited in their ability to make a lame horse sound.
“In 26 years of practice focused on sports medicine, I’ve never seen a lame horse that got better just from adding an oral joint supplement,” said Markell. “Oral supplements might help manage things, but they don’t fix things.
“That said, I think using them is an important part of the overall management,” he continued. “I would say that over 90 percent of the horses we treat in my practice are on an oral joint supplement of some sort. We use it both as a preventative and as an overall reduction of inflammation. We use it in horses that are not lame as a preventative, and whenever I look at a lame horse, almost regardless of his condition, we talk to the owners about the importance of adding an oral supplement to their routine.”
Markell sees some patients have a dramatic response to them and some have no response. “There really is no great research proving or disproving their effectiveness,” he said. “That’s why there are million of them on the market, and that’s why everyone has an opinion on which one is better and which one to use.”
Providing the horse’s body with ingredients that can help moderate the joint disease process is helpful, but when absorbed through the gastrointestinal tract, those ingredients have a long way to travel to get to the joints.
“Some of the products can be orally absorbed and those building blocks, after they’re broken down in the GI tract, can upregulate the processes that are beneficial in decreasing inflammation. Some nutraceuticals can not only decrease inflammation, but they can also make the disease process slow down. But in the end, they’re probably never going to be as potent as a parenteral or intra-articular medication. That’s just how they work,” Frisbie said.
One of the problems is that oral supplements don’t have to be approved. “They’re not regulated in the way as drugs,” said Frisbie. “I can go get some stuff, mix it up in my bathtub and sell it. And that’s legal. And if I market it well enough, people will buy it.
“Nutraceuticals are in many cases more about marketing than content,” he continued, adding that some companies have done quite a bit of research to make sure their products work and have Good Manufacturing Processes facility procedures that ensure that what they say is in the bottle is what’s actually in the bottle.
Taking their limitations into account, feeding an oral joint supplement doesn’t have any real drawbacks, other than cost. They’re safe and can be beneficial. It’s just difficult to quantify their effects.
“You have to be very critical of the response,” said Shauna Spurlock DVM of Spurlock Equine Associates in Lovettsville, Va. “If you notice a problem with your horse, and you reduce his work and start him on an oral supplement and notice a change for the better, it’s not necessarily that the supplement is the source of the fix. It may be a change in routine or a change in shoeing. You want to look really critically, because you don’t want to spend the money if it’s not going to do you any good.”
Consider an oral joint supplement as a preventative measure, or as a way to alleviate some overall stiffness in your horse.
“For sure, if your horse has been on an oral joint medication for two months and you haven’t seen an appreciable difference, then that’s probably not a cost-effective strategy for your horse,” said Markell. “It could be worth trying a different supplement, but I would say more likely you should think about another avenue of diagnosis or treatment. I think of the oral product as more of a preventative and as an addition to parenteral or intra-articular injectible treatment.”
Parenteral Medications: Tried And True
The two most popular parenteral medications, those given via intravenous or intramuscular injection, are Adequan and Legend. Adequan is the only FDA-approved product of injectible polysulfated glycosaminoglycan and is administered via intramuscular injection. Legend is the only FDA-approved product of injectible hyaluronate sodium administered via intravenous injection. Both products can also be used in intra-articular injections as well.
“The companies that created Legend and Adequan are great companies that really did the research and development,” Markell said.
“Adequan incorporates itself into the cartilage and tries to normalize the flexibility and the composition of the cartilage itself. They’ve tested it, so they know it gets to the joint. They put a radioactive dye on it and then injected it into the horse, and then they look at the joint and it lights up in the cartilage,” Markell continued.
Legend works a bit differently; it’s hyaluronic acid. It’s a mechanical lubricant and an anti-inflammatory when it’s put into a joint. There are lots of different brands of hyaluronic acid that people put into joints (Hyvisc, Hylartin V two other examples), and Legend is one of them.
“When it’s injected intravenously, it’s an anti-inflammatory, and it also finds its way to joints and acts as a lubricant,” said Markell.
Using parenteral medications like Adequan and Legend allows the horse’s body to direct the medication where it’s needed. “The body is awesome; it just figures it out,” Markell said. “And rarely do you have just one joint that’s inflamed. Your whole horse is basically in the process of falling apart, and you’ll have inflammation in lots of joints. That’s the cool thing about treating something systemically; it can go to multiple places, and the value of that drug is you get a lot more bang for the buck.”
The catch is that Adequan and Legend are approved as treatments but not as prevention. “We completed a survey of the [American Association of Equine Practitioners] membership, 70 to 80 percent of the vets who responded to the survey were using them in a prophylatic way,” said Frisbie. “They’re not getting used for what they’re actually approved for. I’m not suggesting that’s a bad thing, just that they weren’t ever tested in that manner.
“We do believe that parenteral medications do prolong the time period before normal wear and tear catches up to you,” he added. “It’s like saying ‘Can I get more tread life out of my tires if I drive this way?’ ‘If I give my horse Legend, can I go longer before I have to inject a joint?’ There’s some evidence that suggests that that is true, but that’s not been proven definitively.”
If Markell had a client with a limited budget and a horse showing subtle signs of degenerative joint disease, but without lameness, he would recommend a parenteral medication such as Adequan or Legend.
“If I could only pick one, I’d pick injectibles, because there’s been more solid research on them,” he said.
Intra-Articular Injections: The Gold Standard
So when do you escalate your battle against joint disease from oral supplements and parenteral medications to the level of intra-articular injections? When your horse has a diagnosed disease process in a joint or multiple joints that’s causing lameness or interfering with performance.
“If you have a horse that has a particular joint that hurts, the best thing to do is to treat that particular joint. The analogy is that if you have a fire that’s starting in a trash bin in a parking lot, don’t sprinkle water all over the parking lot to extinguish it. Dump water just in the trash bin. It will put the fire out quicker and more effectively,” said Frisbie.
“If you have inflammation which translates to pain, then decreasing the inflammation decreases the progression of disease. I think people will agree that the most potent way to do it is to treat the joint directly,” he continued.
“Joint injections do what Adequan and Legend do in a more concentrated and direct form,” said Markell. “The idea is that you’re stopping inflammation. That’s really what it’s all about.”
There are many products that veterinarians can inject directly into a joint to decrease inflammation and heal the joint. Hyaluronic acid, as a lubricant to normalize the synovial fluid, and cortisone, a corticosteroid that decreases inflammation, are two popular intra-articular treatments and frequently used in conjunction with one another.
“Cortisone is the body’s natural anti-inflammatory. Studies have shown that if you have two inflamed joints, and you treat one with cortisone once and do nothing to the other one, the horses that have been treated with a specific cortisone have less joint cartilage damage than those that have nothing done. The cortisone put the fire out,” Markell said.
But cortisone doesn’t heal the joint. If the joint requires treatment with cortisone frequently, then the degenerative process is so severe that damage may result with continued stress on the joint.
“You’re not fixing a joint by putting cortisone into it. But by stopping the inflammatory process, you’re lessening further damage to the cartilage,” Markell said.
Medications such as hyaluronic acid and polysulfated glycosaminoglycan can help the joint heal and regenerate cartilage, as can a number of new joint therapies.
Advances in regenerative medicine have brought stem cells, interleukin receptor antagonist protein (IRAP) and platelet-rich plasma (PRP) to the table as intra-articular treatments. These products have added to the veterinarian’s toolbox for treating joint disease.
“Every day I see cases that just a few years ago would have been career-ending injuries and lamenesses,” said Markell. “These therapies are very exciting.”
Frisbie notes that expanding the treatment options has enabled veterinarians to gain headway in frustrating cases of joint disease. “There are different pathways of inflammation and different pathways of pain,” Frisbie said.
“We know that corticosteroids don’t act specifically on the exact same pathway as a product like IRAP, which would make one indicated in one situation and the other in another situation,” Frisbie continued. “If there are horses that responded great to steroids and then they stop responding, maybe you switch to IRAP, and they go back to great response. But there’s no great Venn diagram with trees that you just check off and know you’re right in the end. We know a little bit about the differences in these medications and how they act, but we don’t know everything.”