Hypertrophic osteodystrophy (HOD) is one of the many different bone growth problems that seem to strike the large and giant breeds of dogs far more frequently than the medium and small breeds. HOD has no known cause and is not believed to be genetic; rather it may be combination of several different factors. Some researchers believe it may be caused by a bacterial infection, others indicate a lack of Vitamin C and still others feel it is a nutritional problem caused by feeding high fat and protein diets that cause too rapid growth. Since different puppies seem to react to different treatment modes and programs there is really no consensus on how to treat the condition or what is the root cause.

HOD is typically first noted in the large and giant breeds when they are approximately three to six months old. Puppies that were normally growing and developing start to experience pain in movement, swelling of the bones and joints, lack of appetite and a high fever; often as high as 106 degrees. The fever, as with the pain and swelling may come and go. The swelling may be present in all four legs but typically is in either the front or back legs at various times. Usually either both hind or both front legs will be affected at the same time with single leg problems rarely noted in this condition.

The pain can range from mild to severe and some puppies will only experience brief episodes of HOD while others will seem to have long, ongoing problems with the pain associated with the condition. HOD is diagnosed by a blood sample to test for high white blood cell counts that are typically associated with the condition. X-rays of the affected bones, typically the radius and tibia, will show a thin black line along the growth plate area which indicates a lack of normal growth and development. Serious damage to the joints can occur as the irregular growth causes wear on the joints, leading to early onset arthritis and other chronic joint problems.

Treatment is typically pain management as opposed to correcting the condition. Many vets recommend a broad range antibiotic to help with any bacterial infections, a low protein, low fat diet, supplement of Vitamin C and lots of rest and relaxation for the puppy. These puppies should not be exercised or allowed to run, jump or play, rather they should be kept relatively calm and immobile until the growth plates are normal to prevent bone and joint damage. Steroids may also be used very short term to help in pain management although many vets use these only if the carprofen, aspirin and anti-inflammatories are not effective in managing the pain and swelling.

Many puppies with HOD will grow up to be very well developed and healthy dogs. Some puppies will have long term bone and joint problems and in some cases where bone deformation is severe and debilitating the dog may need to be put down for humane reasons. Early treatment and diagnosis is critical in managing this condition.