The metacarpal bone (also known as the cannon bone) is one of the strongest bones of the horse’s body. This bone rests between the carpus (knee joint) and the fetlock joint. Running along the back of this bone are the major flexor tendons of the distal limb. Horses with metacarpal pain present with a wide range of symptoms: from acute lameness to poor athletic performance. Physical examination findings include swellings, heat, and pain on palpation of the bone and/or tendons. The most common causes of lameness in the metacarpal region include: osteochondral fragmentation, bucked shins in athletic horses, fractures, desmitis (inflammation of the suspensory and check ligaments), and tendon injuries.