Fetlock Joint
The fetlock joint, or ankle, rests between the cannon (third metacarpal) and the long pastern (first phalanx) bones. Tucked behind the fetlock joints are a pair of sesamoid bones encased in the flexor tendons. Horses with fetlock joint pain present with a wide range of symptoms: from acute lameness to poor athletic performance. The forelimbs are more commonly affected. Physical examination findings include fetlock joint distension, heat, and pain on joint manipulation. The most common causes of lameness in the fetlock joint are synovitis (inflammation of the joint capsule), suspensory ligament injury, luxations, osteochondrosis, and fractures (especially in athletic horses). Other abnormalities include: osteochondrosis, trauma, and ligament injury/inflammation.