In the face of new racing medication rules, veterinarians are revisiting treatment approaches for injured animals on layup that trainers hope to send back to the track soon. At the American Association of Equine Practitioners' Convention, held Dec. 7-11 in Nashville, Tenn., Wayne McIlwraith, BVSc, PhD, Dipl. ACVS, ACVSMR, described how these restrictions will impact management of traumatic arthritis and osteoarthritis, specifically.
Historically, administering intra-articular (directly into the joint) corticosteroids has been the treatment of choice to curb pain and swelling. McIlwraith, of the Colorado State University Equine Orthopaedic Research Center, in Ft. Collins, said that the Racing Medication and Testing Consortium (RMTC) has renewed interest in reviewing the timing of joint injections relative to racing. The current, newly drafted recommendation is to prohibit intra-articular corticosteroid injections within seven days preceding a race, along with imposing a 72-hour withdrawal time (meaning the horse cannot receive the medication within 72 hours of a race) on systemic administration of dexamethasone and other short-acting corticosteroids.
Rather than placing these new regulations into immediate effect, the consortium is providing a grace period over the next year to allow “time for veterinarians to adjust their practices and for trainers to adjust training strategies.” The objective of this new RMTC ruling is to facilitate complete compliance with the new regulations in an effort to protect the horses, jockeys, and drivers (in the case of harness racing). He pointed out that other countries--New Zealand and nations in Europe, for example--have previously examined these concerns and have implemented stricter drug restrictions with success.
With these new regulations in mind, McIlwraith described some alternative methods of managing joint disease in racehorses both by using smaller doses of corticosteroids or by not using them at all. One finding of note, he said, is that drug testing has shown that within seven days after administering up to 18 mg of the corticosteroid triamcinolone, levels fall below the required threshold. The same is true for treatment of up to 60 mg with the short-acting corticosteroid betamethasone—horses clear the drug within seven to 10 days. Methylprednisolone, a longer-acting corticosteroid, is also on the list of approved therapeutics.
Another drug useful for managing joints is hyaluronic acid (HA). McIlwraith reported that adding it to acutely injured joints deficient synovial fluid helps restore lubricating function, and that Administering systemic HA (by intravenous or oral route) can be beneficial to equine joints. Additionally, treating joints with polysulfated glycosaminoglycan (marketed as Adequan) has resulted in decreased joint fluid swelling, cartilage fibrillation, and inflammatory effects within the synovial membrane. “Such favorable symptom-modifying and disease-modifying effects are useful when treating joints,” says McIlwraith.
Another strategy is to use therapies that inhibit interleukin-1 inflammatory mediators in order to prevent development of the degenerative cascade in the first place. Gene therapy is one such therapeutic approach that researchers are studying. McIlwraith reported it shows great promise for the future, but it is not yet available for use. Autologous conditioned serum, or IRAP (interleukin receptor antagonist protein) therapy, is a currently available alternative to gene therapy. Other available treatments include platelet rich plasma therapy, stem cell treatment, extracorporeal shock wave therapy, and underwater treadmill rehabilitation as adjunctive approaches.
McIlwraith concluded, “Corticosteroids can still be used but the selection of product, dose, and timing is important.”
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.