Hypertrophic Osteodystrophy (HOD) and the Use of Azithromycin

Hypertrophic Osteodystrophy-And The Use of Azithromycin

Hypertrophic osteodystrophy (HOD) is a developmental disease of young, rapidly growing large and giant-breed dogs. Dogs with HOD exhibit lameness in one or more limbs in association with swelling and inflammation of the growth plate areas (metaphyseal) regions of the long bones (arms and legs).

The onset of clinical signs occurs at 3-4 months of age. This disease has been reported in the Great Dane, Irish Setter, Irish wolfhound, St. Bernard, Labrador retriever, basset hound, greyhound, German shepherd, German short-haired pointer, borzoi, boxer, Dalmatian, Weimaraner, Doberman pincher, and collie.

Clinical signs range from mild pain to severe pain, fever, and loss of appetite with a very poor prognosis .Lameness varies in severity.

The affected long- bone may be extremely swelled at the ends of the bones. Physical exam and history are use to make the diagnosis. Affected bones are warm and swollen on palpation. Fever of up to 106 degrees may be present. Loss of appetite, reluctance to move and weight loss may be noted.

X-rays may show changes in the extremities- showing enlargement of the metaphysis.

Treatment-there is no specific treatment of HOD in the literature as of this date. In our practice we have treated five cases of HOD with Zithromax (azithromycin) with success. Unfortunately, in our practice one case relapsed and again response was positive. Our first case was treated in 1996. Also as of February 2003,  we can now report many more successful treatments using Zithromax.  These are cases referred to our practice via the internet.  We have had 20 cases with a 70% positive  response to treatment.  

If your pet has been diagnosed with HOD, I welcome your E-mail but,  please have your veterinarian contact us. We feel the earlier the treatment is begun the better the response.

The first case was presented after being treated by several other veterinarians with a tentative diagnosis of HOD. This was a 3 mos. old Weimaraner. The temperature was 106 degrees with pain at the end of the bones of the front legs and loss of appetite. It had been treated with corticosteroids and antibiotics with no response.

The second case was recently presented with classical clinical and radiographic signs of HOD.  This was a 4 mos. old Weimaraner.  The response was also very dramatic.   He was recently re-examined and had a full  and uneventful recovery.

There have been reports many years ago that some arthritis and joint pain is due to a mycoplasmal infection. Tetracycline was used to treat mycoplasma at this time. The owner, a physician who is familiar with the use of tetracycline in the treatment arthritis in people years ago is also familiar with Zithromax.

Zithromax is also used to treat mycoplasmal infections.

It also does not cause enamel damage to growing animals. He suggested we attempt to treat the puppy with this medication. Due to the poor prognosis of the disease and non-response to the previous medications, Zithromax was dispensed. In 24 hours the clinical signs and elevated temperature were resolved. The medication was administered for 14 days. There was no recurrence of the disease.

Again, this was only one case initially. But,the response to treatment was dramatic. I am not suggesting that this is the treatment of choice and that Zithromax is curative in all cases, but would encourage more research to evaluate the use if this medication.

RECOMMENDED BOOKS
The Angell Memorial Animal Hospital Book of Wellness and Preventive Care for Dogs

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