Hypertrophic Osteodystrophy (HOD) is a condition of young dogs. The cause of HOD is unknown. It has been reported in young, rapidly-growing dogs since the 1930s. Signs can range from local pain near the growth plate of a long bone to disabling illness that affects multiple organ systems. In some patients episodes occur over and over.
Although HOD is thought of as a “bone” disease, it can also result in eye and nose discharge, nodules of pus in the skin, diarrhea, blood in vomitus and vaginal bleeding. Even lungs can be affected.
Initial episodes may occur as early as 7 weeks of age or as late as 8 months, with 3-4 months as the most common age of onset.
Laboratory testing may show a white blood cell response on the Complete Blood Count (CBC), as well as other non-specific laboratory abnormalities such as mildly increased phosphorous on the Chemistry Profile, which is present in most growing puppies anyway.
Diagnosis is usually made by physical examination, radiographs (X-rays) and bacterial culture and sensitivity of the affected area to rule out bacterial infection. HOD can be definitively diagnosed by biopsy of the affected area, but that is not usually performed.
Research for a cause has been extensive, yet the agent(s) remains elusive. Researchers have even tried to transmit the disease from an affected to an unaffected dog, with no success.
WHO IS AFFECTED?
HOD has been diagnosed in 40 breeds as well as mixed-breed dogs. A breed predilection has been recognized as affecting Great Danes, Boxers, German Shepherd Dogs, Irish Setters and Weimaraners, leading to postulation of inherited tendency. In a study, published this month in the Journal Of The American Veterinary Medical Association, Dr. Noa Safra, et al, of the School of Veterinary Medicine, University of California Davis, observed special relationships among affected Weimaraners. ” It is the only breed in which entire litters and closely related animals are reported to be affected, which indicates a strong heritable component for the disease in that breed.”
HOW IS IT TREATED?
The Weimaraners in Dr. Safra’s study were divided into two groups. One was treated with NSAIDs (Non-Steroidal AntiInflammatory Drugs), the other with corticosteroids. The corticosteroid-treated group responded far better than the NSAID group, further supporting (but not proving) the likelihood that an immune system disorder is an important part of HOD.
See you next week, Dr. Randolph.