Conventional wisdom has usually concluded that one dog year equals seven human years. But on Wednesday, WebMD turned that simple calculation on its ear.
"Dogs mature more quickly than children in the first couple of years," said veterinarians with WebMD. "The first year of a dog's life is equal to about 15 human years, rather than seven."
WebMD vets also said size and breed drive rapidity of age in dogs. By the time a dog is the equivalent of six human years, medium and large breeds begin to age much more rapidly. For instance, when a dog is the equivalent of 10 human years, a small dog would be considered 56 years old, while a large breed would be the equivalent of 66.