Evidence supporting an increased presence of reactive oxygen species in the diseased equine joint

Reactive oxygen species (ROS) are capable of degrading many components of t he joint in the presence of insufficient antioxidant defences, and as a res ult have been implicated in the pathogenesis of joint disease in horses. Ho wever, to our knowledge, evidence of ROS occurring in diseased joints of ho rses has not been reported. The objective of this experiment was to compare differences in synovial fluid protein carbonyl content (as a marker of oxi dative modification of synovial fluid proteins by ROS) and the antioxidant status of synovial fluid between clinically normal and diseased equine join ts. Synovial fluid was collected from the metacarpophalangeal, metatarsopha langeal, carpal and tarsal joints of 4 horses, age 2-5 years, as controls, and from diseased joints (metacarpophalangeal, metatarsophalangeal, carpal, tarsal and/or femoropatellar) of 61 horses, age 2-5 years. Synovial fluid protein carbonyl content was higher (P<0.01) in diseased joi nts as compared to controls. Antioxidant status of synovial fluid from dise ased joints was higher, but not significantly, than that of controls (P = 0 .0595), These findings require further study to determine their contributio n to the overall disease process.