New Hope for Osteoarthritis in Horses

A novel treatment approach for osteoarthritis that involves directly injecting anti-TNF∝ antibodies into the affected joint reduces joint pain and decreases the action of molecules that break down cartilage. Further, this treatment does not appear to have deleterious effects on cartilage.

“Osteoarthritis is a whole-joint disease characterized by inflammation of tissues and breakdown of the articular cartilage lining at the ends of bones inside the joint. One potential cause of osteoarthritis is microtrauma secondary to sport activity, resulting in death of cartilage cells and damage to the extracellular matrix surrounding those cells,” explained Catherine Whitehouse, M.S., a Kentucky Equine Research nutrition advisor.

The extracellular matrix is a key component of cartilage that provides cushioning to the joint during weight bearing. When the joint tissues become inflamed in cases of osteoarthritis, enzymes that break down the extracellular matrix are produced, including matrix metalloproteinases (MMPs). Additionally, various cells within the joint produce the proinflammatory mediator tumor necrosis factor alpha (TNF∝). This mediator causes inflammation and cartilage breakdown.

“Antibodies that bind to and inactivate TNFα may decrease the activity of MMPs, a reflection of reduced inflammation and cartilage damage,” Whitehouse explained.

To test this hypothesis, Argentinian veterinary researchers produced antibodies against TNF∝ and injected them into one intercarpal (knee) or intertarsal (hock) joint of sport horses.^* Twenty healthy horses and 30 horses with osteoarthritis of those joints were included. Synovial fluid samples were collected immediately prior to treatment and again 30 days following the injection. Clinical evaluations were also performed at baseline and on day 30 of the study.

“As expected, clinical scores in the horses with osteoarthritis were significantly higher than healthy horses. One month after anti-TNF∝ intra-articular treatment, clinical scores decreased significantly in the horses with osteoarthritis compared to baseline values, although they did remain higher than the healthy horses,” Whitehouse said.

Additionally, the level of MMPs was significantly higher in horses with osteoarthritis than healthy horses, and those levels were significantly lower 30 days after treatment. Finally, levels of glycosaminoglycans (GAGs), constituents of the extracellular matrix, increased 30 days following treatment, reaching similar levels as found in healthy horses.

These results suggest that early treatment of arthritic joints with anti-TNF∝ antibodies may decrease the destructive activity of MMPs and improve joint comfort.

In addition to finding a potentially safe and effective intra-articular therapy, oral joint health supplements can be added to the diet to provide chondroprotective ingredients such as glucosamine, chondroitin sulfate, and hyaluronic acid.

“Recent research also found that certain omega fatty acids, including long-chain omega-3 fatty acids as well as the novel omega-6 fatty acid, gamma-linolenic acid (often abbreviated GLA), work in the body to promote a less inflammatory response, which may aid horses suffering from osteoarthritis,” Whitehouse remarked.

One of Kentucky Equine Research’s newer products, ReSolvin EQ contains omega-3 fatty acids known to support joint health as well as GLA. This oil is top-dressed onto the horse’s feed daily.

^*Perrone, G., C. Giampaoli, A. Lorenzo Smirnoff, A. Ochoa, R. Pareja, and E. De Simone. 2025. Early effects of anti-TNFα antibodies in horses with osteoarthritis. Journal of Equine Veterinary Science 147:105384.