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Horse health: Take a critical look at supplements in joint care
By Denise Steffanus
Everybody has arthritis, or so it seems – even our horses. There are different types of arthritis, but the most common, called osteoarthritis, occurs as a result of constant wear and tear on the cartilage or a traumatic injury to the joint.
Cartilage covers the ends of the bones that make up the joint and provides a cushion to protect them from grinding together during movement. Synovial (joint) fluid lubricates the joint so it glides smoothly; the joint capsule, which is the fibrous outer covering of the joint, is lined with a membrane that secretes this fluid, and the capsule keeps it from leaking out. The subchondral bone, the layer of bone just beneath the cartilage, forms the critical base for the joint. A pulley system of ligaments, tendons, and muscles moves the joint.
Although joint injuries can occur from a bad step or intense strain from a single competition, most joint problems have a long history. Subtle heat in a joint, a stilted gait, or an odd angling of the limb while walking out usually signal a problem.
Every moment that inflammation exists in a joint is critical because heat breaks down the composition of synovial fluid. Once the viscosity of the synovial fluid thins, friction begins to wear down the cartilage and, as the condition compounds itself, cartilage damage results.
If the horse’s body is given ample time to heal itself, aided by drugs to reduce the inflammation, a single incident usually does not cause joint disease to develop. But if the horse reinjures the joint or uses it before effective healing occurs, the joint sustains additional damage. Bottom line: If the body’s repair mechanism cannot keep up with the ongoing damage, the structures of the joint degrade, causing degenerative joint disease – osteoarthritis.
Keys to joint health
Good husbandry and management of the equine athlete are the keys to maintaining joint health.
“Things that are common sense – basic husbandry, horsemanship, conditioning, proper weight control – can go a long way in reducing the risk for a lot of these athletic injuries,” said Dr. Carter Judy, a board-certified surgeon at Alamo Pintado Equine Medical Center in Los Olivos, Calif. “It’s amazing how horses that are overweight have more stress on their bones and joints because of it.”
The dilemma faced by many horsemen is how to provide the horse with a reservoir of nutritional building blocks that it can draw on for repair of constant microdamage from athletic activity without overfeeding the horse in the process. Feeding a properly formulated supplement that is dense with nutrients for joint health without packing on unnecessary calories is the solution.
Common ingredients in joint supplements are glucosamine, chondroitin sulfate, MSM (methylsulfonylmethane), and hyaluronic acid. Additional ingredients in some supplements include omega-3 fatty acids, cetyl myristoleate, Boswellia serrata, avocado-soybean unsaponifiables, antioxidants, vitamins, and minerals. When added to a balanced diet, these nutrients provide what the horse’s body needs to help it maintain healthy joints and to support constant joint repair.
Judy believes having joint-care nutrients already within the horse’s body enables it to readily draw from that reservoir as the need arises.
“I do think there’s a benefit to early joint supplementation in sport horses and performance horses, for sure, in the sense that we see fewer injuries in those horses that are supplemented than those that aren’t,” Judy said. “And I’ve seen horses that have joint damage come back 10 percent to 15 percent quicker than those not on a supplement.”
Dr. Steve Adair, associate professor and board-certified surgeon at the University of Tennessee at Knoxville, cautions horsemen to carefully evaluate joint-care supplements because many have no equine science to back their claims.
He said, “What I advise owners that want to feed these to their horses is to select a reputable company that has at least attempted to do controlled studies in the horse. If all the evidence the company provides is anecdotal/testimonial or is only from [work in] humans, then they should look for another brand.”
Dr. Stacey Oke, a frequent contributor to equine magazines, has developed criteria called “ACCLAIM” for horsemen to use in evaluating oral joint supplements:
A – A recognizable name. Responsible companies are dedicated to improving the quality of their products. They will provide educational materials for veterinarians and consumers.
C – Clinical research. Companies that stand behind their products have them clinically tested and supply the results of those tests to their consumers.
C – Contents clearly listed on the packaging. All ingredients, active and inactive, should be clearly indicated on the product label.
L – Label statements. Products with realistic label claims based on scientific study results rather than testimonials are preferable. The Food and Drug Administration has regulations regarding the types of claims that can be made on a nutritional supplement. Any label that suggests a treatment or cure should be avoided.
A – Administration directions. Dosing instructions should be clear, accurate, and easy to follow. Products that base their dosing recommendations based upon clinical trials are more likely to be effective.
I – Identification numbers. Products that have a clear identification number for tracking purposes are more likely to have a pre- and/or post-market tracking system to ensure product quality.
M – Manufacturer information. Information regarding the company producing the product should be present on the label, providing contact information for customer support.
First signs of joint disease
The first signs of minor injury to a joint may be so mild that the horse owner does not notice them. Mild swelling and heat may occur within 24 hours after strenuous exercise. The horse may or may not be lame, depending on the extent of the injury. Symptoms usually resolve if the horse is rested, treated with cold-water hosing of the joint, anti-inflammatory drugs, such as phenylbutazone (“Bute”) and corticosteroids (Azium), and topical applications including poultices to reduce swelling and draw out heat. But after time off, if symptoms return the next time the horse is exercised, there may be a more serious problem within the joint.
Veterinarians use X-rays to look into a problem joint, but the images they produce usually are limited to the bone and do not show changes in soft tissue. As a result, the damage often is underestimated.
Computer-enhanced X-rays, magnetic resonance imaging (MRI), and computed tomography (CT scans) now offer a three-dimensional interpretation of joints. Gait analysis through the use of special mats or force plates and high-speed video imaging of the movement of the horse’s limbs enable researchers to identify certain traits associated with the early onset of joint disease.
Repetitive movement of a joint creates friction within the joint, and the resulting inflammation breaks down the viscosity of its lubricating fluid, hyaluronic acid. When the fluid becomes thin, it no longer protects the cartilage that lines the joint, which creates more friction and inflammation with continued use. Soon, osteoarthritis sets in.
At the first hint of a joint problem, the veterinarian X-rays the joint to look for bone chips, which require surgical removal. Absent a chip, the best therapy is to inject the joint with high-viscosity hyaluronic acid. Additional agents, such as a corticosteroid to reduce inflammation and Adequan (polysulfated glycosaminoglycan) or Polyglycan (hyaluronic acid, chondroitin sulfate, glucosamine) to help heal the joint, also may be injected.
“Essentially what we’re doing is preventing that joint from getting injured further, and you extend the racing career of that horse immensely,” said Dr. Mark Cheney, who has spent 46 years on the track caring for upper-echelon racehorses.
Cheney is frustrated by negative publicity about joint injections, especially corticosteroids. He said that if the proper amount of the correct cortisone is used and the horse is hand-walked for several days to allow the medication to work, studies have shown it helps heal the joint and protect it from further damage.
Triamcinolone is indicated for highly moveable joints; methylprednisolone is an excellent steroid for spinous processes of the spine, he said.
Cheney explained the concern about the development of compensatory lameness, when a horse with a painful joint shortens its stride and places more pressure on the opposite leg when it switches leads.
“When you have abnormal pressure on a leg, that’s what creates breakdowns,” Cheney said. “Our whole objective is to prevent breakdowns in horses. If [regulators] cut all this out, thinking that we ought to stop joint injections, you’re going to start having three or four times more breakdowns.”
Cheney said the majority of subtle lamenesses that cause a horse to shorten its stride are those that are difficult to detect, especially by a regulatory veterinarian who rarely has time to do more than watch a horse jog before a race. The daily work of the stable veterinarian is pivotal in preventing serious injuries.
“I spend hours every day examining horses, palpating every joint, every soft-tissue structure,” Cheney said. “Most of them aren’t actually lame; they’re just moving stiff.”
If radiographs indicate that one or more bone chips are causing the joint problem, arthroscopic surgery is performed under general anesthesia to remove them, and the joint is flushed to remove debris.
If a bone chip isn’t removed soon after its detection, the chip grates against the parent bone and shaves off microscopic particles that end up as floating debris in the joint fluid. Moreover, the body recognizes the chip and the debris as foreign matter, and it mounts a process to try to remove those particles, which is an inflammatory reaction that causes pain and the clinical symptoms.
After surgery, anti-inflammatory drugs are administered to minimize swelling and heat. The surgeon typically will prescribe hand-walking for 15 to 20 minutes twice daily until the horse is ready to go back to work or back to training, which may take six weeks to six months, depending upon the severity of the injury.