A puffy fetlock. A knee that’s warm to the touch. A hock that feels just a bit sticky in the trot. All are common performance problems pointing to the possible onset of osteoarthritis (OA). Equine joint therapy is often used to treat these types of OA-inflammation related issues while potentially modulating disease.

Practitioners commonly use corticosteroids for this purpose, but sometimes they employ other medications to be used alone or in combination with corticosteroids. At the 2012 American Association of Equine Practitioners’ (AAEP) Convention, held Dec. 1-5 in Anaheim, Calif., Peter Clegg, MA, VetMB, PhD, Dipl. ECVS, CertEO, MRCVS, of the University of Liverpool Veterinary Teaching Hospital, in Cheshire, U.K., reviewed the value of different non-steroidal joint medications.

Hyaluronan (HA)

Clegg reported that this commonly used intra-articular drug has reasonably good anti-inflammatory effects and can potentially improve cartilage matrix synthesis (the cartilage, which absorbs shock during weight bearing, continually produces more matrix; if arthritis or injury inhibits this ability, the underlying cartilage degrades). With inflammation in a joint, normal synovial fluid loses some of its lubricating ability. Addition of exogenous (originating outside the body) HA through a joint injection might rescue the lubricating properties within an injured joint, he noted.

Clegg said he likes to use HA in a joint that is inflamed but has little to no radiographic changes indicative of osteoarthritis. The best candidates are high-motion joints with evidence of capsulitis (joint capsule inflammation) or synovitis (inflammation of the synovial membrane lining the joint); inflammation in one or both of these structures is often a prelude to OA. Of equine veterinarians surveyed through AAEP, 62% reported using intra-articular HA to treat acute disease of high-motion joints. He advised that an affected horse’s clinical lameness score often does not decrease with HA administration alone; usually veterinarians must combine HA with the corticosteroid triamcinolone to improve lameness. While no scientific data supports the idea that using higher molecular weight HA (which has greater viscosity) offers superior results, he notes that higher molecular weight proteins seem to address the viscosity of synovial fluid better