Radiography of the horse 3. Distal cannon bone and fetlock joint

LAMENESS referable to the metacarpophalangeal (fetlock) joint is common and, in one study, was found to account for 14 per cent of lameness cases in a thoroughbred population. Fractures in the fetlock region are seen mainly in horses working at speed, whereas chronic conditions, such as osteoarthritis, occur in many types of horse. Although facilities for ultrasonography, scintigraphy, thermography, computed tomography and magnetic resonance imaging are becoming increasingly widespread, radiography is still the mainstay technique for imaging the fetlock. Excellent radiographic images are attainable with a little practice and are often diagnostically rewarding. However, the fetlock joint is complex and diagnosis can be challenging ‐ subtle changes can frequently be clinically important, while other more marked findings may not be a cause of lameness. This article describes how to radiograph this region and provides examples of radiological conditions commonly seen in practice.