Exploring pet cancer with veterinary oncologist Stephen J. Withrow

Exploring pet cancer with veterinary oncologist Stephen J. Withrow

May 01, 2009

Cancer in companion animals remains one of the biggest concerns of pet owners, but veterinary oncologists are making important strides in research, diagnostics and treatment choices.

Stephen J. Withrow, DVM, Dipl. ACVS, Dipl. ACVIM, director of the Animal Cancer Center at Colorado State University, is a leading expert in cancer research, whose work appears in numerous texts and scientific papers.

Withrow, who earned his DVM degree at the University of Minnesota, joined the faculty of the College of Veterinary Medicine and Biomedical Sciences at Colorado State in 1978 and was honored as Distinguished Professor in 2004.

He developed a limb-sparing technique to treat osteosarcoma in dogs, one that often is used at human cancer centers, especially for children.

Withrow recently answered some questions on cancer issues in a discussion with DVM Newsmagazine.

DVM: What are some of the most insidious cancers in pets?

Withrow: Skin tumors and other cancers on the outside of a patient are easy. Internal cancers — of the brain, spine, chest cavity, lung, spleen, liver — are the ones that are the foolers or that originate in the blood in places you can't see. Those would be the most insidious.

Public awareness and veterinarian awareness have increased the number of diagnoses of cancers in pets, but that doesn't mean there is an epidemic of cancer. The incidence has not increased. Instead, the number of diagnosed cases has increased. That's more about surveillance on the part of veterinarians and clients.

Cancer is not contagious in 99 percent of cases. Unfortunately, there's this public perception that cancer is running rampant in pets. Again, public awareness, veterinarian awareness and surveillance all contribute to the increased number of diagnoses.

DVM: How is the human-animal bond intensified (or not) in cancer patients and their owners? What are some ways DVMs can address this?

Withrow: Animals have become more critical as part of family units. Today there are more latchkey kids and single parents. And, people are living longer. Once the kids leave the house, what do you have? A dog or a cat. In pets with cancer, where they suffer some consequence of the disease, it gets personalized because of the prevalence of cancer in humans.

DVMs can continue to maintain awareness by understanding the warning signs of cancer published through the Veterinary Cancer Society. Lumps or bumps that continue to grow, weight loss, not eating, vomiting, diarrhea are all signs of potential cancer cases. There needs to be an awareness that cancer should be in the differential diagnosis.

DVM: Do you have any diagnostic tips for identifying cancers early?

Withrow: Awareness is important. A fine needle aspirate for level of suspicion is one method. Understand that a lump is not just a lump. In modern days, we're seeing a tremendous increase in imaging, CTs and MRIs. These tools have really expanded our diagnostic armamentarium. It's important to consider that cancer may be a possibility and to approach from the mindset of wanting to rule it out instead of ignoring it.

DVM: Are there any myths related to pets with cancer that you'd like to bust?

Withrow: People need to understand that cancer is controllable, and sometimes it is even a curable disease. However, you don't have to cure to heal. There's always something that can be done to improve quality of life.

Cure rates for malignant tumors in pets are 25 percent to 30 percent. In human medicine, it's 40 percent to 50 percent for adults and 70 percent to 80 percent for children.

We can provide quality of life at the very least if we're unable to cure the pet. In many ways, with treatment of cancer, there are almost too many choices. Know that doing nothing is also a valid choice as long as you are accurately informed of your choices.