Diagnosis

Diagnosis is based on the history, symptoms, physical exam showing pain and swelling at the growth plates, and with x-rays. The x-rays will show a thin dark line at the growth plate in the end of the ulna, radius, or tibia. Bony inflammation and bone remodeling may also be seen at these sites. Occasionally there may be involvement and changes in the skull and teeth. Dogs often have a fever and occasionally a high white blood cell count.

Speculated Causes

The cause of HOD remains unknown, however, there are many speculations. The autoimmune nature of this is currently under investigation at one university. Viral causes (even Canine Distemper) have been implicated, although they just might be one more kind of stress precipitating HOD. Vitamin C deficiency has been thought to be a cause, however, there is neither documentation nor scientific reason for this in the dog. Vitamin C therapy has not met with much success. Excessive amounts of dietary protein and high caloric intake have been implicated, scientific support for this is also lacking. However, over nutrition does play an important role in Osteochondrosis. An infectious origin has been proposed, and there are reports where hematogenous (blood borne) bacteria have been noted to produce florid radiographic changes in the metaphyses which perhaps could be confused with HOD. Therefore, if not careful, hematogenous or osteomyelitis (bone infection) could possibly be confused with HOD. A good radiologist should be able to differentiate this. Documentation of the use of possible blood cultures, to isolate bacteria, in HOD cases has not been reported. Therefore documentable cases of actual infections have been few. For most cases, the cause is still unexplained.