Over the past 15 years, many pets have come and gone from my life. Pure bred, supposedly pure bred, and complete question mark animals have held big places in my heart for years at a time. But one animal has remained all those 15 years: my first cat, Charlie. He was a spirited, mischievous tom cat rescued off the streets of Chicago by animal control. He's your regular, short-haired, tabby whatever cat.
I used to call Charlie my guard cat when he and I lived alone in Chicago. He ran from nothing, inspected everything, and his big, proud, chest of white earned him the nickname "Daddy Warbucks." While other pets were shuttled back and forth to the vet, Charlie remained seemingly healthy and strong. Whether I fed him Meow Mix from or gourmet, organic varieties from a pet health food store like , he was a rock.
I started to wonder if there was something to be said for coming from the streets like Charlie did. Maybe he came from a long line of cats who watched out for themselves, ate what they wanted, and had street smarts. Maybe all that living had just made Charlie "heartier."
Then I found out that there were theories and studies that said essentially that. I learned about the theory of hybrid vigor, and how studies had actually shown that mix breed dogs were deemed healthier than pure bred dogs.
The most interesting study on this was published in 1997 regarding over 23,500 pet dogs that were patients at North American veterinary teaching hospitals. All the pets were well taken care of by their owners, some even show dogs, with a history of regular vet visits and vaccinations. As their deaths were recorded, it was found that the mutts lived an average of 2.8 years longer than the pure bred dogs (and therefore, gave more love, as they had more days in which to give love). Here is an excerpt from the study:
The decreased life span of pure breed dogs compared with mixed breed dogs in all weight categories in this study suggests that selective breeding of dogs over time for phenotypic traits such as body size has accelerated physiological aging, independent of the effect of size alone. This is consistent with the concept of hybrid vigor in animal and plant species.
Although I haven't read them, apparently other studies have published similar findings, such as German and Swedish studies that reported how mixed breed dogs "require less veterinary treatment" and "are less prone to many diseases than the average pure bred dog" respectively. Of course, all theories have exceptions, and all studies have outliers. I'm sure plenty of readers are now doing the math and remembering the pure bred dog who was healthier than the rescue mutt. I'd love to hear about them.
And of course, this isn't to say that mixed breed pets are more loving. I had a Persian cat who gave me more love in a day than Charlie has given me over most of his life. That Persian was also sick more often, very sensitive to food, and is survived by Charlie. Coincidence? Who cares, I loved them both the same.