Your 3-year-old dog is 21 years old in human years, right? Not according to experts. The general consensus is that dogs mature faster than humans, reaching the equivalent of 21 years in only two, and then aging slows down to more like four human years per year. "Dog Whisperer" Cesar Millan’s site recommends this way to calculate your dog’s human-age equivalent: Subtract two from the age, multiply that by four and add 21.
