A cat's age can be estimated by examining its teeth, coat and eyes. Teeth are especially helpful for determining a feline's age, since the presence or absence of baby teeth helps narrow down an age range. Older cats sometimes display more tartar build-up, but if they regularly see a vet for cleaning, this is less reliable. Senior cats can develop white or gray patches of fur.
Kittens and adult cats have bright, clear eyes with no discharge or tearing. As they age, their eyes may cloud over or start to leak.
If a cat has not had a lot of dental work done, veterinarians often prefer to examine the teeth to estimate age. When a cat is around 3 to 4 months old, permanent teeth are coming in; by 6 months, the process should be complete. When the cat is 1 year old, the teeth are white and clean, but by age 2, there is evidence of tartar buildup, which appears as yellowing in the back teeth. By the time a cat is 5 years old, all the teeth may be yellow and display some wear. As the cat ages, pigment becomes more visible on the gums, and some teeth may be missing.