A look at oral joint supplement ingredients that are backed by science
Can you name one of the most common causes of lameness in horses? If you said osteoarthritis (OA), you’re right. As common as it is, OA remains an incurable disease, and once it presents itself in a joint, there’s no going back.
Knowing this might cause you to sprint over to the supplement aisle of your local feed or tack store, only to be met with an overabundance of oral joint supplements, each label touting an ability to prevent or slow OA progression. But, believe it or not, most of these supplements’ ingredients have no scientific backing in horses, with label claims relying on data extrapolated from research performed in humans and other animals. So which oral joint ingredients do have published results specifically in horses? Let’s find out.
Glucosamine & Chondroitin Sulfate
Glucosamine is an amino monosaccharide (sugar attached to the amino acid glutamine). Chondroitin sulfate is a glycosaminoglycan (GAG), an important component of articular (joint) cartilage.
Mode of Action Both glucosamine and chondroitin sulfate help protect and provide nutrients to joints. Glucosamine is a precursor to (it transforms, chemically, into) GAGs such as chondroitin sulfate. Chondroitin sulfate gives articular cartilage resistance to compression.
Research Researchers have performed many in vitro (in the laboratory, on tissue samples) studies to better understand glucosamine and chondroitin sulfate’s mode of action at the cellular level, either alone or combined. Note that unlike in vivo studies performed on living animals, these experiments do not precisely mirror the conditions found in nature. One involved corticosteroid joint injections, which veterinarians commonly administer to promote joint health. However, some corticosteroids can inhibit proteoglycan (basically a chain of GAGs with a core protein molecule) production, negatively affecting articular cartilage. At the University of Illinois in 2008, Byron et al. found that glucosamine helped protect proteoglycan production when the cartilage was exposed to a corticosteroid.
Using articular cartilage from horse cadaver limbs in 2003, researchers at Michigan State University (MSU) found that glucosamine reduced the expression of genes for matrix metalloproteinases (enzymes responsible for cell degradation) and could help protect joint cartilage.
Another team of MSU researchers took articular cartilage from cadaver limbs and exposed it to mechanical impact to simulate a joint injury. By culturing the cartilage with a combination of glucosamine and chondroitin sulfate (GC), they concluded that GC could help mitigate some of the inflammatory response following joint trauma (Harlan et al., 2012).
Outside of the lab, Martha Rodgers, VMD, of Shephard Hill Equine, in Kentucky, followed 10 hunter/jumper and eventing horses for eight years in a published field study looking at a glucosamine and chondroitin sulfate supplement’s effects on hock injection frequency. Before starting on the supplement, the horses averaged 1.7 joint injections per year at 6.8-month intervals. During the six years they consumed the supplement at the manufacturer’s recommended dose, the horses’ average number of joint injections dropped to 0.85 every 9.98 months. Rodgers did note that six to eight months of consistent GC supplement use is necessary prior to seeing results. It’s also important to note that the level of evidence in this small-scale study is not as strong as that of a placebo-controlled and blinded trial.