My vet estimated the age of our adopted kitties by their teeth and by their eyes. We were told that Halo and Cammie were about the same age when we adopted them. The vet showed us how when he flashed al ight in their eyes, Halo's returned to normal dialation very quickly. Cammie's took much longer. He estimated that Cammie was at least 10 years old . Not 2, like were were told.