Researchers are studying the effects of glucosamine and similar supplements on yearlings to combat the destructive cycle of degenerative joint disease. | © Arnd Bronkhorst
Can dietary supplements such as glucosamine help prevent arthritis in horses? There’s very little research to show which ingredients are helpful for horses in what quantities. But work being done at Texas A&M University suggests that glucosamine and similar supplements may be most helpful for a group of horses that seldom get them—yearlings who are still growing.
“This is truly promising pilot work that may give us a better idea of what dietary intervention strategies hold the most promise and which age range of horses may benefit from them the most,” says Josie Coverdale, MS, PhD, an associate professor in equine science at TAMU. But preventing arthritis won’t be easy or achieved by a single thing, she cautions. “This is a multifactored problem, and we are simply investigating one avenue.”
The approach is based on the fact that, while arthritis is mainly a problem for mature horses, the process that causes it often begins early in life. The stress of early training can cause inflammation in joints, especially the hard-working joints of the legs. The fluid that lubricates the joint turns watery, cartilage is squeezed and inflammatory mediators (proteins the body releases as part of inflammation) begin to damage it. This sets off the destructive cycle known as degenerative joint disease. By the time you notice stiffness and soreness in the joint, the process is well under way. DJD shortens the careers of many horses, and so far no one has found a way to reverse its effects. But what if the condition could be nipped in the bud by blocking the early effects of inflammation?
The TAMU researchers, who included Dr. Coverdale and Jessica Lucia, MS, PhD, a former TAMU graduate student who is now an assistant professor at Sam Houston State University, began by developing a model for joint inflammation. The method they chose allowed them to mimic the pattern of inflammation associated with exercise and to identify markers of cartilage breakdown in joint fluid. It involves injecting lipopolysaccharide obtained from E. coli bacteria into the knee joint.
The researchers used this model to assess the affects of supplemental glucosamine in a group of fourteen yearling Quarter Horses. The horses were fed coastal Bermuda grass hay and a concentrate; half of them also received glucosamine top dressed on their feed at a rate of 30 milligrams per kilogram of body weight. After 84 days of these diets, each horse was given an injection of LPS into one knee and an injection of sterile fluid into the other knee, as a control. The researchers took samples of joint fluid at intervals after the injections. They found that the horses receiving glucosamine had fewer signs of cartilage breakdown in response to inflammation and more signs of cartilage rebuilding.
In addition, Dr. Coverdale is investigating the use of a conjugated linoleic acid product as an anti-inflammatory feed supplement. She has found that it may also help reduce and repair cartilage damage in joints. CLA isn’t used in equine supplements now. “We fed a CLA-based oil that is used frequently in other livestock species,” she says. She was scheduled to present data from that study at the Joint Annual Meeting of the American Dairy Science Association, the American Society of Animal Science and the Canadian Society of Animal Science in July.
“It is important to stress that we used only pure sources of active ingredients in these studies (99% pure glucosamine and CLA oil) and not any particular commercial supplement,” Dr. Coverdale says. “Additionally, this is induced inflammation to achieve a predictable response. A similar type of trial with horses undergoing strenuous exercise to achieve similar inflammation would take months and require a large number of horses to achieve repeatable results.” The TAMU research group is wrapping up a study funded by the American Quarter Horse Association looking at how horses of different ages respond to LPS-induced inflammation. The long-range goal, she says, is to find “a target window of opportunity, the best combination of diet and age, to achieve the most favorable results.”
This article was originally published in the September 2014 issue of Practical Horseman.