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.
Intramuscular Drugs as IA Options Veterinarians commonly administer polysulfated glycosaminoglycans (PSGAGs) intramuscularly, but they can also use these drugs effectively via the intra-articular (IA) route. Currently there's no safety or efficacy data on using pentosan polysulphate, another IM drug, intra-articularly. "However," he said, "No detrimental effects have been seen in pentosan-treated joints compared to those injected with saline."
Regenerative Medicine Practitioners have found the use of stem cells in joints promising for producing cartilage matrix molecules, repair and growth factors, and trophic (nutritional) effects on cartilage. However, Clegg said, "There is no evidence of joint efficacy in the live horse although stem cells may be useful for soft tissue injuries within a joint." He stressed that stem cells currently have no use in end-stage OA cases.
Clegg also described using autologous conditioned serum (also known as the product IRAP for the
interleukin-1 receptor antagonist protein it contains), which caused significant decreases in cartilage inflammation and lameness scores in a carpal chip model of joint disease. "The best indications for its use," reported Clegg, "are with early OA with minimal inflammatory changes in the joint, or in joints with minimal response to corticosteroids."
Clegg said another regenerative therapy, platelet-rich plasma, is best reserved for tendon and ligament injury; he noted it's likely to be more effective in these structures than in joints. He does not recommend using bisphosphonates (Tildren) for OA therapy, either, as they might be toxic to cartilage cells.
In summary, Clegg noted, "There is a lack of evidence for many of these non-steroidal products to achieve profound clinical efficacy. Still, some medications may have a useful, ancillary role in the management of joint diseases."
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.