Performance horses experience extreme physical trauma while training and during competitions. This affects a variety of tissues including muscles, ligaments, tendons, nerves, blood vessels, bones, joints, joint capsules, and cartilage. The most common and consistent cause of damage to the musculoskeletal system is repetitive microtrauma that overwhelms the tissue’s ability to repair itself. Neuromusculoskeletal pain and dysfunctional tissue will compromise the performance of the horse and ultimately cause major tears in tissue if no precautions are taken. Informed and intelligent observation, management, and intervention are essential components in preventing major tissue damage and horse attrition.
Cartilage is the resilient, elastic living tissue that lines the two surfaces of the bones in a healthy joint. Healthy cartilage, alongside joint fluid, protects the bones and absorbs the shock of repetitive impacts during exercise. Cartilage is unique from other tissues because it doesn’t receive blood and is not connected to the nervous system. This means that the cartilage cannot signal pain and must get its nutrition from other nearby structures such as bone and joint fluid. The cartilage’s supply of essential nutrients such as oxygen, glucose, amino acids, vitamins, and minerals is barely enough for normal-day activity. The rigorous training performance horses experience requires much more than what the cartilage can receive, and thus affects the nutritional health of the cartilage. Cartilage acts like an elastic cement or matrix by producing complex molecules called glycosaminoglycans (GAGS) which, when combined with water, give the necessary resilience and compressibility needed for shock absorption and bone protection. When the compression-resisting capacity of the cartilage is reduced or lost as a result of repetitive microtrauma or direct macrotrauma, it begins to physically break down. Joint fluid production is and threduced, andgenerative process of arthritis progresses to joint dysfunction, pain, and then, of course, poor performance. Inflammation of joint structures, cartilage ulceration, surface adhesions, bone chips, bone necrosis and resorption, periarticular vascular occlusions, and a reduced viscosity of joint fluid are all common results of cartilage loss.
As soon as an abnormality is noticed (whether it be a little bit of swelling, some heat, or a slight lameness), observe and evaluate the situation. If your horse is not traveling or performing well on a given day, don’t just keep going hoping things will get better. Take the time to check things out and examine the horse’s legs before and after exercise every day. One of the main reasons horses suffer from joint injuries is fatigue. To prevent the horse from becoming fatigued, make sure the horse is fit enough for the activity they will be doing. Being properly warmed up before exercise and properly cooled down after exercise will minimize the effects of possible injuries.
UC Davis Veterinary Medicine, www.vetmed.ucdavis.edu/ceh/docs/special/Pubs-SuspBrochure-bkm-sec.pdf.