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The AVMA Biological Age Model for Dogs and Cats
The popular belief that one dog year equals seven human years is a mathematical myth. Dogs and cats age much faster than humans during their first two years of life, reaching biological adolescence by the end of year one and full adulthood by year two. According to the American Veterinary Medical Association (AVMA), the first year of a cat’s or dog’s life is equivalent to approximately 15 human years.
By the end of the second year, the pet has aged another 9 human years, making a 2-year-old pet equivalent to a 24-year-old human. After year two, the rate of aging stabilizes and becomes more linear, adding roughly 4 to 9 human years per calendar year depending on the species and breed size.