 How old is your dog in human years? The onset of old age can occur between 5 and 10 years for most dogs, depending on heredity. If your pet is a small breed, she probably won't show signs of aging until she's at least 9. Spaniels and other medium-sized breeds enter their geriatric years around age 7 or 8, while giant breeds (St. Bernard and Great Danes) as early as age 5.
Over the years people have said that each year of a dog's life is equal seven human years. Scientists now feel that this is not a really accurate comparison particularly in the first few years of a dogs life. Below is a chart that gives a more accurate comparison to make when you wonder how your dog's chronological age compares to human years.
Continue to add 4 human years for each year of the dog's life. When are dogs considered geriatric AND likely to manifest problems associated with aging? - Small Dogs (less than 20 pounds) 11.5 years (+/-1.9) - Medium sized Dogs (21-50 pounds) 10.2 years (+/-1.6) - Large Dogs (51-90 pounds) 8.9 years (+/-1.4) - Giant Dogs (more than 90 pounds) 7.5 years (+/-1.3)  From this "must have" book - Dog Owner's Home Veterinary Handbook by Delbert G. Carlson, James M. Giffin |