If you've taken in a stray cat or adopted a cat whose age is unknown, there are some ways to determine her age in cat years. Here are some things vets check to get a general sense of how old a cat is in cat years:
1. A Cat's Teeth: Teeth are a great indicator of a cat's age in cat years. Older cats tend to have more staining than younger cats, assuming the previous owner was negligent in brushing the cat's teeth. And a kitten's teeth first come in between two to four weeks; their more permanent set appears at around four months of age. So if you open a cat's mouth and find permanent, white teeth, the feline is likely to be around a year old. Some yellowing might place the cat between 1 and 2, and tartar build-up on all the teeth indicates that the cat could be between 3 and 5. Missing teeth may mean you have a senior cat on your hands.
2. A Cat's Muscle Tone: Younger cats are more likely to have some muscle definition from their higher activity level. Older cats are usually a bit bonier and may have some extra skin hanging or protruding shoulder blades.
3. A Cat's Coat: The condition of a cat's coat is another great indicator of a kitty's age in cat years. Kittens and younger cats usually have soft, fine coats, whereas older cats tends to have thicker, coarser fur. A senior cat may display grays or patches of white.
4. A Cat's Eyes: Bright, clear eyes without tearing or eye discharge are common in younger cats. A cat with some cloudiness in their eyes is likely to be 12 years old or so. While inspecting the lens, also examine the iris of the eye. Young cats have smooth irises, while the iris of an old cat can sometimes appear somewhat jagged.