Osteoarthritis (OA) remains one of the most important yet incurable causes of lameness in our equine athletes. Owners and veterinarians are constantly in search of methods to prevent the onset of osteoarthritis, reduce its severity, or halt its progression.

Although non-steroidal anti-inflammatory drugs and intra-articular corticosteroids are still important for treating clinical lameness associated with OA, nutraceuticals such as joint supplements have become popular prophylactic (preventive) and conjunctive osteoarthritis therapies. These products, however, are not subject to the same extensive efficacy testing requirements as pharmaceuticals.

One of the largest obstacles veterinarians face when recommending joint supplementation is the lack of adequate research surrounding these products. When choosing a supplement it is important to understand the ingredients. Most joint supplements contain glucosamine and/or chondroitin sulfate. Chondroitin sulfate is an important structural component of articular (joint) cartilage. The chondroitin is most often extracted from cow, pig, or marine cartilaginous tissues. The substance is believed to possess anti-inflammatory properties as well as promote the synthesis of other articular cartilage components such as proteoglycans and hyaluronic acid (HA). Glucosamine, another common ingredient, is most often produced by the breakdown of shellfish exoskeleton. It is a precursor to a major component of articular cartilage, glycosaminoglycans. However, researchers have not shown supplementing with glucosamine alone to be efficacious in horses, and the majority of support for its use remains anecdotal.

Other proposed active ingredients in joint supplements might include HA, omega-3 fatty acid sources, or unsaponified avocado soy. Hyaluronic acid is a major component of articular cartilage and synovial (inside the joint) fluid, but the benefits of oral HA administration remain controversial. In a 2006 study, Bergin et al. reported findings suggesting oral HA administration might result in decreased joint effusion (swelling) after surgery. However, results from a recent study by Carmona et al. (2009) indicated no benefit to oral HA administration in horses with cartilage defects