Dear Doctor: What’s in a number, when that number is a dog’s age?
Q. Is it really seven people years for every year of a dog’s life?
Dear Mr. Pryor,
A. The 7-to-1 ratio is not a bad estimate for a mid-size dog, meaning a dog weighing anywhere from about 20 to 50 pounds. But the ratio changes for larger dogs like Labs and collies, who age more quickly, and for smaller dogs like bichons and Chihuahuas, who age more slowly.
For example, a 6-year-old cocker spaniel is the equivalent of about 42 human years (6 x 7 = 42). But a 6-year-old Lab who weighs 70 pounds is biologically older — more like 45 human years. And a 6-year-old pug who weighs fewer than 20 pounds is about 40 in human years. (If the dog is a giant breed, like a Saint Bernard, at 6 years old she will be around 49.)
Another way of putting it: only 13 percent of giant breeds live at least 10 years. But almost 40 percent of dogs who weigh fewer than 20 pounds live 10 or more years (and sometimes 20).
Don’t drive yourself crazy over the numbers. Just know that a small dog becomes geriatric between ages 11 and 12, on average, while a large dog is geriatric by the age of 9. It’s at that point it may be recommended by your vet that wellness checks go from once a year to twice a year, with different screening tests to look for illnesses that start to creep in later in life.