Elbow dysplasia is the term for an elbow joint that is malformed on X-rays. The mechanism of the malformation is unclear but it may be due to differences in the growth rates of the three bones that make up the elbow joint, particularly the humerus and ulna. In mildly affected dogs the only consequence may be arthritis. In more severely affected dogs, osteochondritis dissecans (OCD), fragmented medial coronoid processes and united anconeal processes can result from the stress in the joint.
Some vets think that these problems may not be secondary but may actually be the primary problems and that the bone changes occur as a result of them. It is difficult to be sure but there does appear to be measurable differences in bone growth in dogs that have elbow dysplasia. There are a number of changes visible on X-rays and the OFA does evaluate X-rays for evidence of elbow dysplasia.