Many owners provide their horses with omega-3 fatty acid supplements purported to support skin, coat, and hoof health; maximize joint health; manage behavior and cognitive issues; and even function as a natural insect repellent, among other perks.

But little evidence exists in the equine literature to support its use in any of these roles. So, C. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, Dipl. ACVS & ACVSMR, from Colorado State University’s Gail Holmes Equine Orthopaedic Research Center, and colleagues tested one of a commercially available omega-3 fatty acid supplement’s potential benefits: improving joint health. This project was part of a PhD program Trinette Ross, MS, conducted at the Orthopaedic Research Center.

“There is evidence that dietary omega-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), can suppress inflammation and in vitro evidence that they can inhibit aggrecanase, which is the critical enzyme involved in degrading proteoglycan in articular cartilage,” McIlwraith explained. “Therefore, omega-3 fatty acids might help manage horses with osteoarthritis or even prevent the development of osteoarthritis in horses.”

The team randomly separated 12 mares into two groups. All horses consumed a diet consisting of an oat/molasses grain mix and Timothy grass hay; the treatment group also received 40 grams of an omega-3 supplement. After 91 days, the researchers induced joint inflammation in all the mares by injecting one carpal (knee) joint with recombinant equine interleukin-1β. They measured various markers of inflammation and joint disease in blood and synovi