HOD - Hypertrophic Osteodystrophy - Barlow's disease, idiopathic osteodystrophy, metaphyseal osteopathy, Moller-Barlow's disease, osteodystrophy II and skeletal scurvy.

Hypertrophic Osteodystrophy (HOD) is a bone disease that occurs in fast-growing large and giant breed dogs. The disorder is sometimes referred to as metaphyseal osteopathy, and typically first presents between the ages of 2 and 7 months.[1] HOD is characterized by decreased blood flow to the metaphysis (the part of the bone adjacent to the joint) leading to a failure of ossification (bone formation) and necrosis and inflammation of cancellous bone.[2] The disease is usually bilateral in the limb bones, especially the distal radius, ulna, and tibia. [ Wikipedia]

Diagnosis

Presto was fine for a couple of days after the initial  flare-up and then the following Friday the same thing happened again! Once more we rushed him to the vets and they recommended X-rays (done a few days later) and he received more pain relief and more antibiotics. 

The X-rays came back completely normal for his spine, legs, hips and tail. I should mention at this point that a friend’s Wolfhound puppy had just been diagnosed with meningitis on the spine after showing similar symptoms to Presto and so we were all very worried about a long term prognosis for Presto. Again, Presto had a relapse a few days after finishing the medication and so we were referred to a local veterinary orthopaedic consultant (Graham Oliver at East Midlands Referrals in Hucknall, Nottingham) for an emergency MRI scan. The MRI finally found the cause of the problem in the top of Presto’s femurs (the long bones in the back legs that go from the knee up to the hip) where a cloudy area in the bone identified an area of infection actually inside the bone itself (see image below):

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A subsequent bone tap and sample taken from inside the femur confirmed that infection was present. The sample was grown on in the lab, but the results were inconclusive (not unusual with samples taken from joints or bone), other than it was definitely some kind of infection.

Taking X-rays to determine a diagnosis is the usual first step with suspected HOD and will certainly rule out several other possible conditions at least. In our case the X-rays were not that helpful and so the MRI scanner was used to go right inside the bones and identify the problem areas. As you can probably imagine though, MRI Scans are not cheap (neither are a set of X-rays) and so the cost of such investigations may be prohibitive if the dog is not covered by pet insurance, so do not be surprised if a ‘tentative’ rather than definite diagnosis is made. In Presto’s case the symptoms were not the usual ones seen with HOD and so other possible conditions were also indentified including Osteomyelitis. Wherever possible, a definitive diagnosis is essential as it will also determine the effectiveness of the treatment given and possibly affect how well the dog responds.

Treatment

Treatment methods for HOD have been somewhat controversial and are also dependent upon the severity and symptoms displayed and also whether the condition is caught at an early or advanced stage. Dogs with severe and late stage HOD may require hospitalization, IV fluids, nutritional support, round the clock nursing as well as a host of medications. Most sufferers are given pain relief in the form of NSAID’s and antibiotics, but some dogs may also be administered immunosuppressants and steroids (the latter 2 treatments may not be applicable for young puppies due to the possible effects on the growth plates). In Presto’s treatment plan daily doses of antibiotics (Ceporex) and anti-inflammatories (Previcox) were used over a period of 3 months to halt and clear up the infection and prevent the bone disintegrating (which would have been disastrous and resulted in euthanasia), alongside pain relief when required (Tramadol). The treatment was very successful and we were thankful that we had caught the condition very early and also had excellent veterinary care from both of our vets.

Causes

You may be wondering why I have put this section at the end of the article, when it is more usual to include it at the beginning? The main reason is that most research is inconclusive and so the cause or causes of the condition are NOT known and therefore less emphasis needs to be placed on what causes HOD. Also, the temptation for many owners is to try and identify ‘what went wrong’ and often this results in them blaming themselves. Please try and avoid doing this if you find yourself in the same situation, concentrate instead on getting a quick diagnosis and treatment for your dog. Some research studies into the condition have suggested possible triggers for HOD including:

In Presto’s case we believe that it was a viral infection that set off the HOD as we found the infection present in the femurs on examination.

Summary

In conclusion, be reassured that HOD is not that common, particularly in Wolfhounds and if diagnosed and treated, the condition can be dealt with very successfully (Presto made a full recovery over several months). Also, it is one of those conditions that look like several other things and prompt veterinary attention is essential. The cost of treatment can run into several thousands of pounds however, so it is another great reason to ensure that your dog has adequate insurance cover. In very severe cases HOD can be fatal, but generally the prognosis is good.