Purebred Dogs and Cancer

Understanding the high incidence of cancer and other diseases in pure bred dogs.
Kathryn E. Vinson, MS, CCRC

This week my family lost one of our four legged loved ones.  Rocky was a 16-year-old blue heeler mix.  He had an undeniably long and blessed life, from being rescued from a Phoenix animal shelter at two years old to living the life with two boys on a ranch in Central Texas. His illness came on quickly, and thankfully it didn’t last long.

Rocky’s passing got me to thinking about his long life, versus the shortened lifespans of many purebred dogs.  Growing up, my family always had Golden Retrievers.  Statistics tell us that goldens are terribly prone to cancer, with each dog having an approximately 60% chance of developing some kind of cancer in their lifetime. The first Golden that we had was Steele – he was a sweet boy that died of liver cancer at 9 years old.  Then his son Duke had testicular cancer, but was able to live to the ripe old age of 14 after being neutered. Duke’s two puppies – Duchess and Baron – both succumbed to hemangiosarcomas at 11 and 8 years of age, respectively.  From an entirely different line of dogs, littermates Sam and Logan both also died of hemangiosarcomas within 4 months of each other.  And now, my Mom’s current golden, Ruari, has had to have treatment at Texas A&M for mast cell tumors.

So, why is it that Rocky lived to be 16, hardly ever getting ill other than arthritis, but the Golden Retrievers that I had growing up all developed cancer at one point in their life or the other?  Although environmental factors can play a role, it is felt that the answer often lies in genetics.

Jerold Bell, DVM of the Tufts University School of Veterinary Medicine explains that the predisposition to certain conditions in our purebred animals is due to a fixed gene pool. Okay – what the heck does that mean? Well, if you look at Golden Retrievers, for example, they all descend from a common gene pool – those very first Goldens that were then bred to one another to produce the breed that we know today.  Although breeders work to minimize inbreeding by researching pedigrees, at some point up the genealogical chart – ancestors are shared.  Without the introduction of new blood into the line, the chances of recessive genetic traits increase dramatically.

PetMD tells us the following nine purebred breeds are at the highest risk for developing various cancers:

• Rottweilers – osteosarcoma
• Bernese Mountain Dog – mast cell tumor
• Bouvier des Flanders – general higher risk of cancers
• German Shepherd – general higher risk of cancers
• Great Dane – osteosarcoma
• Labrador Retriever – general higher risk of cancers
• Bichon Frise – general higher risk of cancers
• Boxer – general higher risk of cancers, brain tumors
• Golden Retriever – lymphoma and hemangiosarcoma

So, back to the beginning of this post – why did Rocky live so long?  There isn’t one answer, as a dog’s health, just like a human’s, is influenced by a plethora of factors. What Rocky had going for him, that Duchess and our other goldens didn’t, was that introduction of new genetics that could overpower the recessive traits so predominant in purebreds.

If your family has experienced the loss of a pet, or is dealing with a sick animal, take a look at Dealing With the Loss of a Beloved Pet for information that may be helpful in your grief. Another good read is What veterinarians wished you knew before euthanizing your pet; while this decision is never easy, it is a call that a lot of us have to make.  This is a decision only you and your family can make together.  Keep in mind that when that time comes for your beloved pet – your veterinarian cannot tell you what to do, from a legal and ethical standpoint. What your vet can do is help you understand what possible treatments and palliative care are available to your pet.

From all of us here at Cancer Horizons, much love to all of the fur babies and their families that have dealt with cancer.