Rock Doc: Family dogs’ forebears mean lives are shorter

It’s just a fact: Most of us outlive our dogs. Indeed, for people who are dog owners throughout their lives, a lot of grieving is guaranteed. Fido No. 1 dies, is replaced by Fido No. 2, who also dies, and so on down the long line of dogs in our households.

I was reminded of how short a dog’s life is compared to ours when I read Ted Kerasote’s book, “Pukka’s Promise.” Kerasote is the best-selling author of “Merle’s Door,” a book about the relationship he had with a mixed-breed dog named Merle. At the end of that book, Merle died of cancer. After a few years, Kerasote got a purebred puppy he named Pukka.

As Kerasote explains, dogs don’t live for a long time because they are basically wolves, and wolves are short-lived. In the wild, wolves tend to live only three or four years because they prey on animals that can injure and kill them. Because of the difficult conditions of their lives, wolves breed earlier than animals like grizzly bears, and they have more offspring each year.

The domestic dog, which is a wolf in friendlier clothing, follows this same pattern, reaching sexual maturity rapidly and having litters of squirming puppies that may number eight or ten. What works as a survival strategy for wolves as a species guarantees us dog-lovers that we will grieve for the death of our canine companions multiple times during our much-longer lives.

But not all dogs are created the same. Different breeds of dogs have different longevities. In general, the giant breeds like the Great Dane live shorter lives than smaller dogs. And because they avoid certain genetic problems, mixed-breed dogs (the honest mutts that fill dog pounds from coast to coast) tend to live longer.

So far, so good. But can we say more about specific expectations of canine life spans? Enter Dr. Kelly Cassidy, the curator of Washington State University’s Conner Vertebrate Museum. In her free time and as a hobby, Cassidy has considered the longevity issues of dogs. She made a study of sources that list how long different breeds live versus what breeder surveys report about their own dogs. Surveys like that aren’t the hardest of scientific evidence, but they do give some data.

Cassidy’s work suggests that quite a number of dog breeds don’t appear to live as long as people like to believe. For example, German shepherds are often said to live about 13 years. But Cassidy’s reading of breeder surveys indicated a more realistic number might be a bit less than 10 years.

“That’s really quite a difference,” Cassidy said to me.

Selective memory and wishful thinking may result in the difference between expectations of a dog’s life and what actually is likely to unfold for Fido.

In any event, the wolf heritage of dogs guarantees they won’t live as long as we’d like. That’s the basic fact we all know, and it’s the bottom line I take away from Kerasote and Cassidy.