Bucked Shins in Horses
“Bucked shins” are part of the disease complex known as dorsal metacarpal disease. Bucked shins is a painful, acute periostitis on the dorsal surface of the third metacarpal bone. It is seen most often in the forelimbs of young Thoroughbreds (2-yr-olds) in training and racing, and less commonly in Standardbreds and Quarter horses. This injury can occur bilaterally and usually occurs sequentially, with the left leg being affected first because horses are trained and raced in North America in a counterclockwise direction. Bucked shins may be the result of high-strain cyclic fatigue caused by excessive compression on a bone that has not remodeled enough to tolerate the stress placed on it. Stressed bone forms a new layer of bone at the point of stress. This new bone is weaker and, in the process of rapid bone formation, the periosteum becomes elevated and inflamed.
Diagnosis is typically by clinical examination and history (soreness over the dorsal aspect of the cannon bone, soreness after high-speed work or the first race, or soreness the day after). Radiography is beneficial to determine the amount of periosteal reaction and if actual stress fracture(s) are present in the dorsal cortex. Treatment typically consists of altering the training schedule to short bursts of speed work 2–3 times a week. Rest from training is also important until the soreness and inflammation resolve. The acute inflammation may be relieved by anti-inflammatory analgesics and application of cold packs. Screw fixation with or without osteostixis is the method of choice to treat radiographically demonstrated stress fractures.