The role of genetics in canine cancer

Dr. Gerald Post, DVM, is a board-certified veterinary oncologist who oversees an organization dedicated to finding a cure for cancer in both pets and people. He has multiple practices in Connecticut and New York and serves on the board of the Animal Cancer Foundation (www.acfoundation.org)

Dr. Gerald Post, DVM, is a board-certified veterinary oncologist who oversees an organization dedicated to finding a cure for cancer in both pets and people. He has multiple practices in Connecticut and New York and serves on the board of the Animal Cancer Foundation (www.acfoundation.org)

By Terri Perrin

Of all medical conditions that your canine companion can develop, few are met with more shock and trepidation than cancer. As with cancers in humans, canine cancers can be scary, but it is important to be aware that not every diagnosis is a death sentence. Thankfully, veterinary oncologists around the world are making great strides in treating and curing many types of cancers in dogs.

The good news is that surgery, chemotherapy, radiation and holistic practices are all now being used in combination to treat and, in many cases, cure canine cancers. By some estimates, one out of every three dogs will develop cancer in their lifetime. While it’s difficult to pin down why our pets get this disease, some breeds are genetically predisposed to specific forms of cancer.

What does “genetically predisposed” mean? 

Your dog has inherited genes from both parents. Genes are part of your dog’s molecular structure called Deoxyribonucleic Acid or DNA. These genes dictate your dog’s size, coat type, body structure, head shape, temperament and other characteristics, as well as its predisposition to some types of cancers. To be “genetically predisposed” means that in your dog’s family lineage, specific types of cancers have been known to occur at a higher than average rate.

In both animals and humans, genetic predisposition (sometimes also called genetic susceptibility) is an increased likelihood of developing a particular disease based on an individual’s genetic makeup. A genetic predisposition results from specific genetic variations that are often inherited from a parent. These genetic changes contribute to the development of a disease but do not directly cause it. Some people or animals with a predisposing genetic variation will never get the disease while others will, even within the same family. Genetic variations can have large or small effects on the likelihood of developing a particular disease.

What is the research telling us?

Veterinary oncologists have been collecting cancer-related data for 25 years and have statistically proven that different cancers more commonly affect several types of purebred dogs. (See sidebar.)

“Although we have known that some breeds and mixes develop cancer more commonly than others, it was not until recently that some of the reasons for this phenomenon were exposed,” explains Dr. Gerald Post, DVM, board-certified veterinary oncologist in the U.S. and board member of Animal Cancer Foundation. “The decoding of the dog genome added immensely to our understanding of why certain breeds and mixes have a higher cancer risk. Scientists are now inching closer to allowing us to answer the question that all of us want answered: Why did my dog get cancer?

“Scientists studying the factors that contribute to increased cancer risk in people point to four main factors: genetics, environment, diet, and infectious causes,” adds Dr. Post. “It is probable that all people and animals have some inherent risk for developing cancer and that these four factors work to either increase or decrease that baseline risk. I hope that by manipulating one or more of these factors, we can dramatically decrease the rate of cancer in our pets and ourselves.”

Dr. Post respects the fact that when a positive cancer diagnosis is given, many pet guardians like to search the Internet for information. Unfortunately, not all information is good information so be cognizant of where the information comes from. He highly recommends the research paper entitled Breed Predispositions to Cancer in Pedigree Dogs (http://www.hindawi.com/journals/isrn/2013/941275/ ) This article is written by a qualified expert and is published in a respected scientific journal. It presents the real facts, backed by sound research, for those who want to learn more.