2001-Thu Jan 19 22:50:16 MST 2017
Vetstreet. All rights reserved.
Vetstreet does not provide medical advice, diagnosis, or treatment. See Additional Information ›
Recently I wrote about the
random bad luck behind the development of many canine cancers. While it’s true research has shown that a roll of the dice determines most cases of cancer, there is an area where the incidence of cancer is not a function of bad luck but of something more concrete: genetics. As a follow-up to my earlier article, I thought it would be useful to look at why this is so and to also consider that, if there is a silver lining here, it is that the predisposition for developing cancer among certain
breeds may provide researchers with tools to better study cancer in
dogs and ultimately in people.
From a genetic standpoint, each breed of purebred dog is a closed, isolated population. Because a registered dog must have ancestors who were registered as well, no new genes enter a purebred dog population, except in extraordinary situations sanctioned by the breed registry. Every purebred dog is a relative, albeit a distant one, of the other dogs within that breed. Since most dogs are never bred but instead live out their lives as pets, the “doggie gene pool” remains relatively small. Selective breeding for each registry maintains the puppy face of the
Bernese Mountain Dog, the mahogany coat color of the Hungarian
Vizsla and the fluffy black fur of the
Flat-Coated Retriever. However, genes that increase a dog’s risk of developing cancer also seem to have tagged along with the genes that control things like facial features, coat color and fur fluffiness. Those genes place these three breeds at the top of the list of dogs with an increased risk of developing certain types of cancer.
If there is an upside to the limited genetic diversity of purebred dogs, it is their unsurpassed ability to elucidate the genetics behind various
cancers and other hereditary diseases. Using the map of the canine genome and the extensive family trees from purebred dogs, the DNA of
dogs with a high risk of developing a certain kind of cancer can be compared to dogs with a low risk of developing that type of cancer. The genetic differences identified are likely areas of the canine genome where the genes for increased cancer risk lie. Once the genes are identified, tests can be developed and used to help avoid breeding individual dogs with the “bad genes.” Right now, scientists are just at the point of identifying these genes.
In part, the common ancestry of dogs has perpetuated mutations that increase the risk of or directly cause cancer. Genetic analysis of wolves and dogs shows divergence of dogs from ancestral wolves around 11,000 to 16,000 years ago. Ancient Australian and African breeds, such as the Dingo and
Basenji, became distinct about 2,000 to 3,000 years ago, but most of the modern breeds of dogs, like Mastiffs and
Herding dogs, are quite recent innovations in dog breeding, stemming only from Victorian times.
Mastiff Group, which for genetic purposes here is different from the traditional
Hound Groups we see breeds organized into at dog shows, is a genetically determined grouping of related dogs. This
Mastiff Group includes several genetically related dog breeds that have an increased risk of cancer. For example,
Boxers are prone to
mast cell tumors, Bernese Mountain Dogs to histiocytic sarcoma, Golden Retrievers to
lymphoma and hemangiosarcoma, and
Rottweilers to osteosarcoma. The exact genetic abnormality resulting in an increased risk of cancer in these and other predisposed breeds is still under intense investigation and supported by the
American Kennel Club’s (AKC) Canine Health Foundation and the
Morris Animal Foundation, to name two of the major funding agencies behind this groundbreaking research.
Like this article? Have a point of view to share? Let us know!
Take our breed quiz to find your next pet.
Get all the best pet news and information sent right to your inbox!
Thank you for subscribing!
Want to choose the best food for your
pet? Here's why you shouldn't fear
preservatives or fall for marketing…
Electronic cigarettes may be growing in
popularity, but their higher concentrations
of nicotine can poison cats and…
Are you handling your pet the right way?
Our vet shares five things your pup wishes
you knew about picking him up.
We combed through 505,270 kitten
names to determine the hottest male
and female monikers of the year.
We scoured our database of 1.1 million
dogs to find out which male and female
monikers reigned supreme this past…
The laid-back American Wirehair’s crimped, coarse coat requires almost no brushing or combing.
Check out our collection of more than 250 videos about pet training, animal behavior, dog and cat breeds and more.
Wonder which dog or cat best fits your lifestyle? Our new tool will narrow down more than 300 breeds for you.
If the video doesn't start playing momentarily,
please install the latest version of Flash.
Thank you for subscribing.