Conditions affecting the fetlock of Thoroughbred racehorses

Some conditions of the fetlock occur more frequently or almost exclusively in racehorses. Many are probably stages along a continuum of one main disease process. Stress related bone injury can lead to subchondral bone sclerosis, which can progress to subchondral bone lucency, and then to stress fractures. Stress fractures can lead to catastrophic fractures if undiagnosed, or can lead to osteoarthritis (OA) more chronically. Many conditions of the fetlock in racehorses can be diagnosed using a combination of the clinical history, the physical examination, diagnostic analgesia, and imaging such as radiography or ultrasonography. Scintigraphy is invaluable for the diagnosis of fetlock conditions in racehorses as stress related pathology is so prevalent. Advanced imaging modalities such as magnetic resonance imaging (MRI) and computed tomography (CT) complement other imaging methods and are increasing our understanding of various disease processes. Younger horses in the early stages of training can develop fetlock pain from contact between dorsoproximal P1 and the distodorsal cannon bone during maximum extension. This can lead to synovitis alone or with fragmentation of the proximal saggital ridge region or proximal P1. Damage to the articular cartilage can also occur. These horses usually show a mild lameness, a joint effusion and pain on flexion of the fetlock. Many of the horses will recover with a reduction of exercise and symptomatic treatment. Medication of these joints with corticosteroids in 2-year-olds should be avoided so as not to impede the healing. Hyaluronic acid is a reasonable treatment choice.  […]