Melbourne veterinarian, Dr Belinda Oppenheimer BVSc (hons) MANZCVS, examines the high prevalence of osteosarcoma in greyhounds and its links with breeding priorities within the racing industry.
While generally very robust, like all purebred dogs, greyhounds have a few diseases which we see in them more frequently compared to the general dog population. Sadly, one of these diseases is the dreaded osteosarcoma, also called ‘osteo’ or ‘OSA’. Osteosarcoma is an aggressive form of bone cancer, which
occurs most commonly in the limbs. Like most cancers, the incidence of osteosarcoma increases as greyhounds get older, though middle aged and even young greyhounds can be affected. Typical clinical signs include lameness, swelling of the leg, and sometimes, ‘out of the blue’ severe limping: this is typically associated with a tumour which has gone unnoticed previously causing a sudden break in a weakened bone, called a pathological fracture.
Greyhounds, and other large dog breeds such as Rottweilers, are at the highest risk of developing this disease. Studies have shown that greyhounds are up to 17 x more likely than crossbreed dogs to develop osteosarcoma, and approximately 50% of all cancer diagnoses in greyhounds will be bone tumours. As such, it’s important that as greyhound guardians, we act quickly and seek prompt medical attention if we notice any potential disease signs in our hounds. Genetics are thought to play a major part in the high incidence of the disease in greyhounds. As greyhounds are bred for use in racing, with their ‘useful’ life usually over within five years, there is no breeding focus on reducing longer term health issues with a potential genetic link such as osteosarcoma. It is unknown at this time if the stressors of racing play a part in disease predisposition. Clinical signs are often very telling, but your veterinarian will likely confirm the diagnosis with x-rays.
Osteosarcoma typically causes a ‘moth eaten’ appearance on x-rays as it eats away at the bone; secondary fractures can also be detected. A sample/biopsy may be taken from the bone if there is uncertainty. X-rays of the chest to check for tumour spread is also very useful.
Unfortunately, the long term prognosis after a diagnosis of osteosarcoma is very poor. This is largely due to the fact that the cancer spreads aggressively; even if a tumour is investigated straight away, there is already a 90% chance it will have started to spread throughout the body, usually first to the lungs. Given the nature of how the tumour eats away at the bone, and further if bone fractures occur, it is also a very painful condition. It is very important to have a frank and informed discussion with your greyhound- knowledgeable veterinarian prior to deciding on a course of action.
Treatment of osteosarcoma is focused on controlling pain, and limiting tumour growth as much as possible. For older dogs with ongoing health problems such as arthritis, the fairest course of action may be palliative care with strong pain relief, while keeping quality of life at forefront of mind, and ensuring the decision to say goodbye is made before any pain cannot be controlled. Amputation is the first port of call for more intensive treatment, removing the primary cancer and the associated bone pain. While this can greatly improve quality of life, survival with amputation alone is only approximately 4 – 6 months. The best option is to amputate the affected leg and then undergo chemotherapy to try and fight the cancer spread elsewhere in the body. Survival time following amputation and chemotherapy is approximately 10 – 12 months.
While osteosarcoma is a constant concern for greyhound carers, it is important to be aware of the early signs to watch for, and importantly, to cherish all the time we have with our hound friends and ensure they all live the wonderful lives they deserve.
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4. Harari J. 2008. Research Update: The prevalence of and risk factors for canine appendicular osteosarcoma. https://www.dvm360.com/view/research-update-prevalence-and-risk-factors-canine-appendicular-osteosarcoma. Accessed 7 March 2022.
5. The Greyhound Health Initiative. 2022. Sarcomas. https://www.greyhoundhealthinitiative.org/sarcomas/. Accessed 7 March 2022.