Osteoarthritis (OA) is the most common type of degenerative joint disease in horses (Goodrich & Nixon, 2006) and humans (Moskowitz, 2009). The disease is a major source of pain, disability and socioeconomic cost worldwide (Woolf & Pfleger, 2003), and results in severe welfare issues and economic losses for humans and for horse-related industries.Osteoarthritis is a complex disease that involves all parts of the joint. It may be caused by a number of different factors, ranging from chronic low-grade micro insults to acute trauma and infection. The involvement of inflammation produced by synovium and chondrocytes is central to the pathogenesis, with inflammatory cytokines, metalloproteases and other inflammatory mediators being present in synovial fluid of patients with OA (2006). The resulting joint pain manifests as lameness (Schlueter & Orth, 2004) and the joint capsule inflammation causes swelling and fibrosis, resulting in additional pain and decreased range of motion of the affected joint. No curative treatments exist for this disease, but early symptomatic treatment can reduce pain and the cartilage-damaging effects of the inflammatory products, and decrease the progression of cartilage destruction and fibrosis of the joint capsule (Goldring & Otero, 2011). In horses, a common treatment regime consists of systemic administration of non-steroidal antiinflammatory drugs (NSAIDs; Goodrich & Nixon, 2006).