Hypertrophic Osteodystrophy in Dogs

In one of our previous articles, we discussed a type of bony overgrowth calledhypertrophic osteopathy, a condition that is sometimes implicated in cases of lung cancer. Bone overgrowth can occur with other disease processes, and so it is important to know the difference.Hypertrophic osteodystrophy is one such example, but how does it compare to other conditions?

Hypertrophic osteodystrophy is an orthopedic disease that affects young large and giant breed dogs. The average age at diagnosis is anywhere from two to six months, and it primarily affects long bones like the radius, ulna, or tibia. The most commonly affected breeds are Great Danes, Golden Retrievers, Labrador Retrievers, German Shepherds, and Weimaraners.

Long bones are made up of different sections. The shaft of the bone is called thediaphysis, each end is called theepiphysis, and the layer in between these segments is called themetaphysis. This is where the “growth plate” is located and allows for normal bone growth.

In patients with hypertrophic osteodystrophy (HOD), there are large amounts of bony overgrowth at the level of the metaphysis, and it often will affect the opposite limb. It affects the forelimb more than it affects the hind limb, and HOD affects male dogs more than it does females.  

There is no definitive cause for HOD in dogs, but it is suggested that infections fromEscherichia coli or canine distemper virus can cause it. A majority of dogs with HOD tend to eat diets that are very high in protein or have been over-supplemented with calcium and vitamins. 

Puppies with HOD will appear lame on the affected limb or limbs, and in severe cases, there may be obvious swelling at the metaphysis of the affected bone. The swelling can cause great pain, especially when touched, and fever is also a common sign. 

Mild signs such as appearing tired or lethargic are sometimes more difficult to detect. HOD patients may have seemingly unrelated symptoms such as lack of appetite, diarrhea, dehydration, and thickening of the paw pads known ashyperkeratosis. Hyperkeratosis is very common in pups who have distemper virus. 

If you suspect that your dog has HOD, make sure to schedule an appointment with your veterinarian. They can help diagnose HOD based on your pup’s clinical history and by performing x-rays. Additional testing such as blood work can be useful for helping to rule out an infection, routine vaccinations from an early age may help prevent HOD from occurring. 

Most cases of HOD are self-limiting which means that they will resolve on their own. Dogs with mild signs can improve in days while others may take months for recovery, and HOD can also reoccur as puppies continue to grow. Mild pain can be mitigated with non-steroidal anti-inflammatory drugs but severe pain may require multi-modal pain management in order for your pup to feel comfortable again.

For some HOD patients, severe bony overgrowth can contribute to angular limb deformities once they are fully grown. This can lead to the early onset of arthritis, and sometimes surgical intervention is necessary to correct the deformity.

To help prevent HOD, make sure that your puppy is on a large breed or giant breed diet that is formulated for puppies. Avoid giving any supplements unless directed to do so by your veterinarian since most commercially available diets are balanced for complete nutrition.

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Hypertrophic osteodystrophy primarily affects young large and giant breed puppies, and while there is no definitive cause, infections and high-protein diets and supplements may be part of the problem. If you feel that your puppy is lethargic or painful, it is important to contact your veterinarian as soon as you can. Most cases will improve after a few months, but early intervention is vital so that you can mitigate your pup’s pain!  

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