The most accurate way to determine a cat's age

Does anyone know the best way to determine a cat's age? When I found Buster on the street in 2000, the vet at the SPCA hypothesized that he was about 1.5 years by looking at his teeth. I carried that information over to the other vet. So his records state that he is about 9 years old.

However, when I went to the holistic vet last week, the doctor told me that Buster is more likely in his EARLY TEENS! What does that mean - 10 or 11 or older like 13 or 14? Needless to say, I am devastated because I feel that I lost 3 or 4 years with Buster. If he is much older, then he'll probably pass away quicker than I imagined (he is fairly healthy other than his chronic constipation). Now I don't know what to believe! Are there any other ways to figure out a cat's age?

The vet says his eyes and teeth are fantastic and that he usually sees clouding on the lens or abseces in the gums for a cat of Buster's age. The vet also said that he has very little tartar build-up. Nonetheless, he said that teeth alone is not an accurate predictor. I should say that Buster is somewhat bony and has muscle atrophy, according to holistic vet.

the older they are the harder it is to tell age ... the teeth are commonly used as age markers

I wouldn't worry too much about the varying estimates. It's just differing vet opinions, and it's likely that it was easier to measure his age when he was very young than it is now. There's no reason to trust one estimate over another (though personally I wouldn't believe a holistic vet vs. a regular vet whose training is based on tested science).

Even if you did know his current age for certain, it wouldn't tell you how long he'll live or how good his later years will be. What's more important is whether he seems healthy and happy.

Have you asked the holistic vet why he/she said Buster is older? Also, keep in mind that most vets (conventional or holistic) don't have a ton of experience with senior cats. They see dogs more than cats to begin with, so there are fewer senior cats under their belts. As a result, they may extrapolate a bit from their limited previous experiences--if one 13 year old cat had certain eye changes, they might assume other cats with those eye changes are also about 13. Poor Odo aged 8 years in a matter of months--the first shelter thought he was 6, the second shelter thought he was 10, and my vet guessed him to be closer to 14 years old. Regardless, he's a sweet and healthy boy and we'll likely have a lot of years left together. My younger kitty Willow, who the vet thought was 9 months when I adopted her and who the shelter said was a year old, was the one who ended up passing at the age of 8.75-9 years old. Unfortunately, we never know for sure how long these kitties have with us, so we just have to enjoy every minute of it (even when they do wake us up an hour before the alarm ).

Thanks everyone for your help. I guess that makes sense. Buster was small when I found him in 2000 and I thought he was a teen cat. Maybe he was malnutrioned at the time because he was homeless. The SPCA simply looked at his teeth and guessed. After I found him, he started growing fast and looked more like an adult cat.

I think the holistic vet thinks he's older is because of his bony structure and muscle atrophy. In 2005, Buster started to look very thin. The vet ran blood and urine tests to rule out any serious conditions. Amazingly, his lab work came out negative. But he still looks very anorexic despite weighing 11.5 pounds. It's just that he looks bony because of his older age.