Scientists dis­covered long ago that cancer is cancer. It doesn’t care if you have two legs or four – it looks the same under the microscope, spreads to the same locations, and reacts the same way to treatment. Despite advances in knowledge, cancer remains the leading cause of death in dogs beyond middle age and the second leading cause of death in people. Millions of pets and people will be diagnosed with cancer this year alone. While extraordinary resources have been devoted to diagnosing and treating this cruel disease in people, it turns out, the answer to cancer may be walking right beside us.

The promise of comparative oncology

In the late 70’s and early 80’s veterinary surgeon Dr. Stephen Withrow and radiation biologist Dr. Ed Gillette, both at Colorado State University, had the idea that cancer could be treated in animals, much like it was in humans. To take it a step further, they hypothesized that naturally occurring cancers, particularly in dogs, were similar to many cancers in people, making dogs a relevant model in which to study the disease for both species. Their pioneering vision laid the groundwork for a field of comparative oncology; the study of naturally occurring cancers in more than one species.

Why dogs?

Studying dogs with cancer helps us learn more about human cancer.

•  Cancers in dogs develop naturally, just like in people.
•  Dogs live in the same environment, breathe the same air, and drink the same water.
•  People and dogs have similar immune systems, and more than 400 diseases affect us in the same way.
•  Dogs share 85% of our genetic make-up.
•  Dogs have shorter lifespans providing study results more quickly.

Comparative Oncology

Naturally occurring cancers in dogs and humans share many features, including:
•  Appearance under a microscope.
•  Tumor growth and spread.
•  Response to conventional treatment (chemotherapy, surgery, or radiation) and novel therapies.

Canine clinical trials decrease the time and cost of drug development.
•  Clinical trials in dogs offer a more flexible design than human studies.
•  The length of a pet animal study is 1-3 years vs. 5-10 years in people.

Pets with cancer helping people with cancer

Over the last few decades, an increasing number of loving owners have started seeking specialized veterinary care when their pet receives a cancer diagnosis. Thanks to these committed pet lovers, veterinary oncologists have had incredible opportunities to improve patient care, quality of life, and outcomes for pets with cancer. And as they have discovered better diagnostic tools and treatment options for their pet patients, veterinarians have shared their results with human oncologists.

Clinical trials have been vital to advancing veterinary cancer care. The Flint Animal Cancer Center’s One Cure clinical trials program is the largest in veterinary medicine and includes seven dedicated staff members. In 2018, the program managed 31 clinical trials to study more effective therapies for a variety of cancer types including, osteosarcoma, lymphoma, soft tissue sarcoma, and brain tumors. One Cure also supports basic comparative oncology research focused on a variety of projects, including immunotherapy, metastatic disease, molecular oncology, pharmacology, and radiation biology. Lab discoveries lead to clinical trials which lead to better treatments. To learn more about One Cure and to support this critical work, please visit

Advances in cancer treatment thanks to canine clinical trials

Radiation for Oral Cancer (1980s, Colorado State University): A National Cancer Institute sponsored trial in companion dogs defined a new radiation protocol that was then applied to human treatments.

Linking Infections and Survival (1990s, Colorado State University): Scientists learn that dogs that develop infections after surgery for bone cancer live longer than dogs without infection. This was later proven in children and is an active area of research.

Bone Cancer Chemotherapy (1993, Colorado State University): A National Cancer Institute sponsored trial confirmed that intra-arterial chemotherapy was more effective than I.V. drug delivery in canine patients with bone cancer and is now widely used in children.

Immunotherapy improves Osteosarcoma control (1990s and 2000s. Colorado State University and University of Wisconsin):  Liposome encapsulated muramyl tripeptide-phosphatidylethanolamine (L-MTP-PE) is an immune modulator first tested in dogs with osteosarcoma that demonstrated efficacy when given after chemotherapy.  A similar study in people with osteosarcoma delayed the time to metastasis.

Losartan combination therapy for metastatic osteosarcoma (2010s-Present, Colorado State University): Scientists discover a new combination therapy for patients with bone cancer that helps prevent the spread of cancer to other parts of the body and treats existing tumors by removing immune suppression and blocking new blood vessel growth. After promising results in laboratory study, the therapy is piloted in a canine clinical trial at the Flint Animal Cancer Center. Results lead to full review in dogs and a pilot study in children with metastatic osteosarcoma. Learn more…

Disrupting the status quo in cancer research

The Flint Animal Cancer Center and the University of Colorado Cancer Center are partners in the world’s most advanced comparative oncology research program. Their work is revolutionizing cancer research. Together, scientists and clinicians are developing new treatment strategies that can be rapidly and safely studied in pet dogs to inform human studies. While a clinical trial may take 5-10 years in people, it may only take 1-2 years in dogs, which means less time before researchers know if a treatment is working. This powerful relationship is fueling discovery, innovation, and hope for both people and pets with cancer. Current collaborations include studies of head and neck cancers, bladder cancer, bone cancer, immunotherapies, and drug development.

The time, talent, and treasure invested in comparative oncology research is a win for all cancer patients. Growing the number of collaborations between veterinary and human oncologists and scientists will speed up discovery and one day, hopefully, lead to a cure.

To learn more about comparative oncology, visit the National Cancer Institute’s Center for Cancer Research.