Hypertrophic Osteodystrophy (HOD) is a bone disease that usually affects young, rapidly growing, large breed dogs. The disease has been called several other names, including metaphyseal osteopathy, skeletal scurvy, Moller-Barlow’s disease, and osteodystrophy II.. The disease produces moderate to severe lameness and pain in dogs and often affects multiple limbs. The exact cause of Hypertrophic Osteodystrophy is not fully understood.
HOD is a disease of young, rapidly growing dogs. It usually strikes puppies between the ages of 3 to 6 months, but can strike as late as 2-3 years of age. It is primarily a disease of large or giant breeds of dogs, thereare occasionally exceptions to this rule. As with most of the young, large breed bone disorders, it statistically affects males more commonly than females. There does not appear to be an increased incidence in any one particular large or giant breed. There does not appear to be a strong inherited or genetic link.
Dogs that are stricken with HOD often show signs of mild to moderate painful swelling of the growth plates in the leg bones, most commonly affecting the ends of the radius, ulna, (long bones from the elbow to the wrist) and tibia (long bone from the knee to the ankle). Affected dogs may show lameness and reluctance to move, may be lethargic and even have a poor or absent appetite. Fever, sometimes severe, wax and wane in some cases. HOD usually affects both legs at the same time, that is, bilaterally. The signs may come and go and resolve on their own, or if the fever is very high for long periods and the bone involvement severe, the dogs may suffer permanent structural damage or is some cases even die.
Diagnosis is based on the history, signalment, signs, physical exam showing pain and swelling at the growth plates, and with x-rays. The x-rays will show a thin radiolucent (dark) line at the metaphysis (near the growth plate) in the end of the ulna, radius, or tibia. Bony inflammation and bone remodeling may also be seen at these sites. Occasionally, there may be involvement and changes in the skull and teeth. Dogs often have a fever and occasionally a high white blood cell count.
The treatment is generally supportive. Since this is a very painful condition anti-inflammatories and painkillers such as Rimadyl, Previcox, Deramax, Metacam, and Zubrin are often prescribed to reduce inflammation and pain to treat symptomatically. In addition, some affected dogs are given a broad-spectrum antibiotic. Strict rest on a soft bed is recommended, as well as feeding a highly palatable food will help to encourage some dogs to eat. In severe cases steroids may need to be given to control the pain, but this is avoided if possible, given possible adverse effects in young canine patients. Vitamin C is often supplemented though its benefit may be questionable. In most cases, the patient will seemigly outgrow this disease, with clinical signs typically gradually spontaneously becoming less severe and resolving by 2 years of age.
The prevention lies in understanding what causes this disease. Unfortunately, there is currently incomplete consensus on the cause of this disease. Some have hypothesized that there is a bacterial cause.. The bony changes and occasional high fever support this possibility. The difficulty in obtaining a bacterial culture from the sites and the often-poor response to antibiotic therapy alone, certainly question this argument.
Another suspect in the disease is vitamin C. Some dogs that present with this disease show very similar signs and bone changes as people afflicted with scurvy (a skeletal disease caused by vitamin C deficiency). In addition,some HOD dog have been shown to have a lowered blood vitamin C level. However, dogs are known to synthesize their own vitamin C and do not seem to have a nutritional requirement for this vitamin. In several studies and in practice, feeding affected dogs high doses of vitamin C alone has often failed to help. As a result, other researchers speculate that the low blood level of vitamin C may be a result of the disease, not the cause.
The most accetped cause for HOD may be nutritional. There is evidence that several bone diseases of young dogs are linked to feeding an excess of protein and calories in the diet.. Studies have not been conclusive, though many owners of large and giant breed puppies begin transitioning from densele caloric, high fat and protein puppy food, to adult food at 6-7 months, rather than at the traditional 1 year. It is possible that this disease may be caused by several of these aforementioned factors. Clearly more future reasearch will not needed to more conclusively pinpoint the cause of HOD nad other skeletal growth disorders.
Roger L. Welton, DVM
Founder and Chief Editor, Web-DVM.net
President, Maybeck Animal Hospital
Article updated 11/5/2012