Fractures
Fractures of both the proximal phalanx (P1) and the canon bone can involve the fetlock joint. Treatment options and possible outcome depends on the exact severity and location of the fracture.
Any suspected fracture should be treated as an emergency and veterinary attention is required before attempting to move the animal.
Fracture of the sesamoid bones
Fractures of the sesamoid bones, at the back of the fetlock, are usually caused by excessive forces being applied to them by the suspensory ligament due to overextension of the fetlock. Usually only one of the sesamoids is affected, although complete breakdown of the suspensory apparatus can damage both.
Sesamoid fractures cause a sudden lameness that can be moderate to severe that improves rapidly with rest only to return on the resumption of exercise. The joint is usually enlarged with pain on palpation.
Diagnosis
X-rays are required for diagnosis and to assess treatment options.
Treatment
Simple box rest and immobilization is not usually adequate for a return to athletic function, therefore, surgical repair and/or removal of any fragments of bone is often recommended.