Corticosteroids can be an equine joint's best friend or its worst enemy, depending on the veterinarian's approach: Has he or she made a clear diagnosis of osteoarthritis? How many times has the horse's joint been injected already, and is the horse a high-performance athlete? Which joint is the practitioner targeting, and what's going on with the rest of the horse's body? Because there are many considerations for applying corticosteroid joint injections safely and effectively, Peter Clegg, MA, VetMB, PhD, Dipl. ECVS, CertEO, MRCVS, from the University of Liverpool Veterinary Teaching Hospital, in Cheshire, U.K., addressed their use at the 2012 American Association of Equine Practitioners' (AAEP) Convention, held Dec. 1-5 in Anaheim, Calif.
"The use of corticosteroids in joints involves risk, especially where there is no definitive diagnosis," Clegg remarked. But with appropriate care and use, veterinarians might be able to mitigate these risks. He urged practitioners to first resolve a primary problem as thoroughly as possible before resorting to corticosteroid joint injections. That said, this stepwise approach can be a more expensive route. Clegg acknowledged the pressure equine veterinarians face from trainers and owners demanding joint treatment without a clear diagnosis.
Clegg remarked that there seems to be a "maintenance injection" culture in the United States unlike anything he has seen in Europe. "Corticosteroids have a profound effect on chondrocyte (cartilage cell) metabolism and are not at all advisable in the absence of joint inflammation," he warned. He urged practitioners to pursue a clear diagnosis if they suspect joint pathology rather than reach immediately for the corticosteroids and a needle, particularly when treating racehorses or performance horses.
"If a horse requires repeat corticosteroid administration (to improve its soundness and athletic ability), then rethink other options to maintain athletic longevity," he added. "A recent paper relating to corticosteroid use in racehorses revealed some interesting data in which horses received from one to 74 intra-articular corticosteroid injections over a lifetime--such frequent use of a powerful anti-inflammatory drug may not always be in the best welfare of the horse."
Once the veterinarian defines a joint as truly needing treatment, the drug he or she selects depends on the joint involved. "Is it a high-motion or low-motion joint?" he asked. "Is the joint afflicted with capsulitis or synovitis (inflammation of the joint capsule or the synovial membrane, respectively, both of which are often a prelude to osteoarthritis)? Or is the horse experiencing end-stage osteoarthritis (OA)?"
Based on an AAEP member survey, responding practitioners who routinely treat joints preferred injecting the steroid triamcinolone (77%) in high-motion joints and methylprednisolone (73%) in low-motion joints.
Corticosteroids pose a variety of risks to the patient. Infrequently, these injections can cause articular sepsis (bacterial infection of the joint), which might be difficult to diagnose early on because the steroids themselves can mask clinical signs for up to 10 days.
Many veterinarians worry about the risk of horses developing laminitis in the wake of this treatment, although scientists have made no definitive link between the devastating hoof disease and corticosteroid joint treatment. However, if a joint treatment candidate is obese, Clegg recommended using a low dose of corticosteroids or avoiding treatment altogether; an obese horse suffers from hormonal aberrations that increase his risk of developing laminitis under the best of circumstances.
Another concern regarding corticosteroid use in joints is the potential for catastrophic breakdowns, such as what is seen in racehorses. He stressed that because corticosteroids can mask pain from an injury, racing a medicated horse with an undiagnosed subtle prodromal (early stage) fracture could cause a devastating breakdown.
In conclusion, Clegg recommended that practitioners first establish a thorough diagnosis and only use corticosteroids in joints that will truly benefit from this therapy.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.