Joint pain due to osteoarthritis (OA) is one of the major causes (60%) of lameness and lost training days in horses. To alleviate this pain, veterinarians most often turn to non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids, but how do all the different medications stack up against each other? René van Weeren, DVM, PhD, Dipl. ECVS, from the University of Utrecht’s Faculty of Veterinary Medicine, in The Netherlands, evaluated pharmacologic methods of OA pain management and their recent advances at the British Equine Veterinary Association’s 51st annual Congress, held Sept. 12-15 in Birmingham, UK.

Osteoarthritis is characterized by a vicious cycle of inflammation and cartilage degradation–one leads to the other, said van Weeren, and there is no cure. Veterinarians can manage affected horses’ pain, however, using either systemic or local treatments.

Systemic Treatment of Joint Pain

NSAIDs are the most important and commonly used pain relievers. They work by inhibiting the enzyme cyclooxygenase (COX) and impeding production of pro-inflammatory molecules called prostaglandins. Most traditional NSAIDs inhibit both COX-1 and COX-2 enzymes (COX-2 causes inflammation and pain in the body, while COX-1 is associated with beneficial functions such as protecting mucosal barriers in the gut), whereas newer NSAIDs are “more selective COX-2 inhibitors and have a superior gastrointestinal safety profile,” said van Weeren.

Phenylbutazone (Bute) is the most commonly used NSAID, and it’s highly effective as well as inexpensive, said van Weeren. However, he added, its effect on cartilage is questionable, it has a narrow safety margin, and it might cause gastric ulcer development. “Although proven effective, comparative research on clinical efficacy vs. other NSAIDs in horses is limited, and information on the effects on the primary disease process is even scarcer and conflicting,” he explained