This is a nasty infection of the long bones, often seen in German Shepherds and other large breeds. It can affect any age. Affected dogs are very ill and lame in the affected leg. Affected areas show heat and swelling. X-ray changes are very similar to those seen in bone cancer It is caused by a fungus called Aspergillus which destroys bone and spreads through the body. It can often be detected in the urine and this is used as part of the diagnosis. How it gets into the bones is not quite certain, but it may be from an injury to the leg or possibly if the fungus gets into the bloodstream e.g. through the nose.
Diagnosis is based on x-ray changes, bone biopsy (to rule out Osteosarcoma), and urine analysis.
Treatment is involved and is not always successful. Expensive anti-fungal drugs have to be given by a vet and repeat tests performed to ensure it is clearing up.