Cancer scientists go to the dogs for help

WCVM oncology group

The oncology clinical team at the WCVM Veterinary Medical Centre. Back row (left to right): Dr. Monique Mayer, Dr. Valerie MacDonald, Jojo and Kim Foster. Front row (left to right): Melissa Underhill, Magnus, Dr. Sally Moore, Oliver and Dr. Kirsty Elliot. Photo: Myrna MacDonald.

Though similarities between human and canine cancers have long been recognized, researchers are just now beginning to explore the potential of using canine oncology research models.

“Canine oncology research models are still really new,” says Dr. Valerie MacDonald, associate professor of medical oncology in the WCVM’s Department of Small Animal Clinical Sciences.

MacDonald, who treats hundreds of dogs diagnosed with cancer each year, is a strong advocate for the use of canine models to enhance health care for animals and people. She recently began working with Dr. Troy Harkness, a professor in the University of Saskatchewan’s College of Medicine, on a potential treatment for lymphoma — a cancer that develops resistance to chemotherapy.

Harkness has been doing in vitro research into an anti-diabetic drug called metformin that may potentially reverse this resistance in tumour cells. In 2013, MacDonald, Harkness, human endocrinologist Dr. Terra Arnason and small animal internist Dr. Casey Gaunt will use metformin on dogs with lymphoma that have developed a resistance to chemotherapy drugs.

Research results from the canine clinical cases could in turn benefit human oncology investigations.

There are several advantages to studying lymphoma, osteosarcoma and other cancers in dogs:

• Many research trials, for example, are done using artificially induced tumours in lab rats. But the tumour may not behave the same way as if it was naturally occurring. As well, the rat’s immune system is suppressed to varying degrees.

• Cancers can have genetic and environmental components. While most lab rats come from a relatively small gene pool, osteosarcoma can occur in dogs of many different breeds, lending a genetic diversity to any studies that are done.

• Dogs also share an environment with humans, opening up opportunities for investigations into environmental factors.

• Cancers such as osteosarcoma are relatively rare in humans yet common in dogs, giving researchers a larger number of cases to study.

• Dogs regularly reach old age, yet their lifespans are significantly shorter than that of people. This allows researchers to study naturally occurring cancers in a relatively compressed time frame.

Canine osteosarcoma in particular has a history as a good model for treatments that may be beneficial to humans.

When dogs aren’t good candidates for limb amputation (the preferred treatment for osteosarcoma), veterinary surgeons can offer specialized surgeries known as “limb spare” procedures.

In limb spare procedures, instead of amputating the entire limb, only the cancerous section of bone is removed. It’s replaced with either a steel rod or a piece of bone from a bone bank. Radiation of the affected limb may also be used if amputation is not an option. Because the tumour is highly metastatic, chemotherapy is used in conjunction with surgery or radiation therapy.

Using this limb spare procedure in dogs has helped to shed light on new limb spare procedures for children diagnosed with bone cancer.

Click here to read a recent article about the use of canine research models in the New York Times.


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