You know that whole theory that if you multiply your dog's age by seven years, then you get his equivalent "human age"? Well, it apparently doesn't work that way, according to Daily Kibble. They say "there is no precise formula" but "what veterinarians do know is that large dogs tend to have shorter life spans than smaller dogs."
Think about it this way...Each human year for a Mastiff is going to count more in dog years than it does for a Pekignese. Says Daily Kibble: "As a guideline, a dog whose ideal adult weight is at least 50 pounds will generally be considered to have reached his senior years at about 7 years old. A dog whose ideal weight is between 20 to 50 pounds is generally considered geriatric at about 9 years old, and a dog who weighs below 20 pounds is usually considered geriatric at about 10 years old."
Make sense? I don't know about you, but I find it a little sad that any dog would be considered "geriatric" at just seven years of age.