How is a cat's age determined?

Question: How, exactly, is a cat's approximate age determined? We took in a stray cat that we'd been feeding for several weeks, and we are curious how old he is. I know that something about cats' teeth is a clue, but I don't know what to look for, exactly. What are the guidelines for telling your cat's age?

Answer: Because I am not a veterinarian, I can only respond in broad, general terms. While teeth are sometimes a good indicator, they are not foolproof. For that reason, veterinarians prefer to examine the whole cat. Here are a few of the feline organs veterinarians check to determine the age of a cat. . . .read the rest of my response

Can you guess the approximate age of these two cats?
_{Photo Credit: © Franny Syufy}