Why Does my Pet Have Cancer? (And the Genetic Connection)
The last three out of four dog deaths in my family were the direct result of cancer. All within the past ten years. Which is why when owners ask me why their pets have been so afflicted, I often offer the following observation by way of condolence: If we’re lucky enough, all of us will live long enough to die of cancer.
Cheekiness notwithstanding, I totally believe in the inexorability of cancer. Cellular repair mechanisms being what they are, it seems unlikely (statistically speaking) they’d fail to slip up at least once in a “normal” dog’s age.
The trouble comes in when pets die an unnaturally young death. After all, cancer in a thirteen-year-old Rottweiler with a host of other issues (hip dysplasia, hypothyroidism, chronic cruciate disease) can’t quite compare to the shock of being told that your otherwise healthy seven-year-old cat has been diagnosed with a brain tumor. (Not that I would mention this to the Rottie’s bereaved owner.)
Worse still is the knowledge that the breed of dog or cat you selected was especially prone to cancer — but you didn’t know it. And here you were, thinking you were getting yourself a golden retriever because the breed is such a hardy, family friendly pooch.
That’s what happened to author Melinda Beck, who wrote an article that appeared in the Wall Street Journal this past Tuesday. Titled, When Cancer Comes With a Pedigree, Beck recounts the tragic downturn her beloved seven-year-old golden, Cody, succumbed to as the cancer he had been suffering from took his life. So sad. But what she made of her dog’s demise was an homage to cancer-prone dogs everywhere.
Don’t believe the WSJ can publish a tear-jerker? Read this:
I started writing this column while lying on the floor with a golden retriever who didn't have long to live. All goldens are friendly and eager to please, but Cody was especially affectionate and goofy. He loved to sit on park benches and he seemed to think that everybody he met had nothing better to do than pat him. Most people agreed.
Cody was only seven, middle-aged for the breed, but a fast-moving cancer was filling up his lungs, making it harder and harder for him to breathe.
Cody had been diagnosed with a cancerous condition we call metastatic lung disease. In these cases, it’s clear the cancer has metastasized from an original location elsewhere in the body to the lungs (certain types of cancers tend to do this). It’s considered a uniformly terminal disease in pets.
Poor Cody. Seven is young. But I’ve seen pets as young as a year old develop cancer. It’s never an easy thing to tell an owner — and worse still when my patients should’ve been enjoying ball-chasing, laser-hunting, and other prime-of-life pastimes. How do you explain that?
That’s where the WSJ article comes in. It tries to make some sense of the senselessness of cancer by dwelling on the depressing connection between certain purebreds and cancer. Get a load of the stats:
About 1 in 3 dogs die of cancer, about the same rate as people. Some breeds, however, are more susceptible than others. Here are the breeds with highest to lowest incidences of cancer. (Average life expectancy shown in parentheses.)
Boxer (10½ years)
Golden retriever (12)
Bernese mountain dog (8)
Boston terrier (13 years)
English bulldog (8)
Scottish terrier (13)
Cocker spaniel (12)
Irish setter (12 years)
Schnauzer (standard 12; miniature 15)
Labrador retriever (12½)
Beagle (13 years)
Poodle (standard 12; miniature 15)
Dachshund (15 1/2)
Sure, it’s helpful to know there are genetic factors at play when it comes to canine oncology. But we already knew that about humans, right?
Which is partly why, for me, knowing there’s a hereditary link makes me feel not even a little bit better. In fact, now that the cancer can somehow be rationalized (to some extent, anyway), it makes me wonder what’s wrong with all those breed clubs that refuse to open their books up to new, cancer-free blood. If there’s a way to mitigate the risk through better breeding, then why insist on working with the same afflicted gene pool, as AKC-wed golden retriever breeders do?
Ultimately, there’s no explanation good enough to account for why so many of our pets — canine or feline — succumb to cancer. But there's one thing I do know: If there's a way to mitigate the risk through better breeding, we need to start taking steps to get it done.
Dr. Patty Khuly