Complete rupture of a cruciate ligament is usually a catastrophic injury resulting in severe lameness and joint instability. Strains and partial rupture of the cranial and caudal cruciate ligaments may result in variable lameness, depending on the severity of injury. Effusions of the femoropatellar or femorotibial joints are sometimes present. Lameness is usually improved by intra-articular anesthesia of the femorotibial joints. In some horses, radiographic changes may be evident at the sites of attachment of the ligament with enthesiophyte formation or focal areas of radiolucency. Ultrasonography of the cruciate ligaments is difficult but may demonstrate some lesions. However, in many horses, diagnosis is confirmed only by arthroscopic examination.
Conservative treatment involving rest, systemic NSAIDs, and intra-articular corticosteroids is indicated in horses with acute injuries. If horses do not respond to conservative treatment, arthroscopic surgery is recommended to debride loose and torn ligament fibers.
The prognosis for return to athletic function depends on the severity of injury. Horses with complete rupture have a grave prognosis. Horses with moderate to severe injuries have a poor prognosis for return to athletic function, whereas horses with mild injuries have a fair prognosis.