Medial luxations occur most often in the toy breeds and are characterized as congenital luxations.
Lateral luxations occur infrequently and are seen primarily in large breed dogs as the result of trauma. Although the luxation may not occur until well after the dog has reached skeletal maturity, these luxations are considered congenital because of the anatomic predisposition to luxation. Dogs can be affected bilaterally. On palpation the acromion process appears prominent and it is difficult to extend the shoulder. Radiographs will confirm the diagnosis.