Hypertrophic osteodystrophy (HOD) in growing dogs

Hypertrophic osteodystrophy, often shortened to HOD, is a bone disease that affects young, fast-growing dogs of large and giant breeds. It can be very painful, but many puppies recover well with veterinary care.

What is hypertrophic osteodystrophy?

HOD causes painful swelling around the growth plates, the areas near the ends of the long bones where growth happens. It is not caused by an infection in the bone. It can affect any of the legs, and the bones that grow fastest tend to be worst affected. Extra bone can build up in the affected area, so the ends of the bones may look wider on X-rays.

Males are thought to be affected more often than females.

Signs to look for

Signs of HOD can include:

• lameness, or reluctance to walk or stand;
• warm, swollen and painful areas near the ends of the leg bones;
• a fever that comes and goes, sometimes as high as 41°C (106°F);
• tiredness and refusing to eat;
• weight loss and dehydration;
• diarrhoea;
• breathing problems, as some puppies develop pneumonia.

If your puppy shows any of these signs, contact your vet. Contact your vet straight away if your puppy can't stand, stops eating or drinking, has trouble breathing, or shows other alarming signs such as coughing up blood or bloody diarrhoea.

What causes HOD?

The cause is unknown. Ideas that have been suggested include:

• a bacterial or viral infection elsewhere in the body;
• vitamin C deficiency (an older theory with little support);
• too much protein and too many calories in the diet, leading to very fast growth.

Some studies have looked at a possible link with vaccination, but this is not proven. Do not skip vaccinations without speaking to your vet.

How is it diagnosed?

Your vet will ask about your puppy's history and symptoms, and examine them for pain and swelling near the growth plates. X-rays of the legs are an important part of the diagnosis.

Treatment

There is no cure for HOD, but treatment aims to control pain and support your puppy while the episode passes. Your vet may prescribe pain relief. Puppies that are badly affected may need to stay at the vet practice for nursing care, fluids if they are dehydrated, and help with eating if they can't eat on their own.

Episodes can last days to weeks. Many dogs recover after one or two episodes, but some have repeat episodes, and a few are left with bowed legs or other lasting changes. Only give medicines your vet has prescribed for your puppy.

Caring for your puppy at home

Follow your vet's advice. In general:

• keep your puppy rested in a small, comfortable, well-padded area;
• if your puppy is willing, take them out on a lead for short toilet breaks only;
• don't allow running, jumping or rough play during an episode;
• don't give any supplements unless your vet advises it;
• ask your vet before changing your puppy's diet.

Breeds at risk

HOD has been reported most often in large and giant breeds, including the Akita, Alaskan Malamute, Boxer, Chesapeake Bay Retriever, Dalmatian, German Shepherd, Golden Retriever, Great Dane, Irish Setter, Irish Wolfhound, Labrador Retriever, Newfoundland and Weimaraner. Other large breeds can be affected too.