A horse’s athletic success depends on the health of his joints, and veterinarians are continually studying up on how best to maintain athletic joints and manage injury. During a presentation at the 2011 American Association of Equine Practitioners convention, held Nov. 18-22 in San Antonio, Texas, Larry Bramlage DVM, MS, Dipl. ACVS, an equine surgeon at Rood & Riddle Equine Hospital, in Lexington, Ky., gave veterinarians an "introduction to joint therapy." He described the lubrication mechanisms within the joint and the natural responses of the joint to injury.
Bramlage pointed out that when a joint is damaged, veterinarians see typical and consistent signs: a lame horse and a distended joint with increased amount of watery joint fluid. While the human impulse is to "fix" these types of signs, Bramlage pointed out that these very clinical signs are "a superficial part of the joint’s response to insult."
The interior of the joint consists of the articular cartilage, which covers the bone ends, and the synovium that lines the inside of the joint capsule. Both cartilage and synovium are bathed in joint fluid, but they are lubricated by different means and have different responses to insult.
Bramlage referenced a study evaluating pain within the joint in which examiners found that while pulling on the synovium itself was excruciating, cartilage has no nerve endings and cartilage stimulation is not painful.
Hyaluronic acid (HA) lubricates the synovium, while water lubricates the cartilage through a sort of "sponge" mechanism. Weight-bearing compresses cartilage and fluid is forced out, pre