This question, typically rephrased as, "How long will my cat (or dog, horse, chinchilla, etc.) live," is something veterinarians hear on a daily basis. Of course, nobody can tell you how long a particular individual’s life span will be, but statistics can give us a general idea of what to expect.
The feline life expectancy that I came up with when I was doing the research for my book, Dictionary of Veterinary Terms: Vet-Speak Deciphered for the Non-Veterinarian, was 10 to 15 years. I averaged the somewhat disparate values I found in several reliable references to come up with these numbers. Another statistic that I commonly use in practice is that cats that spend significant unsupervised time outdoors tend to live to be about 7-years-old, while indoor-only cats can be expected to make it to around 14 years of age.
I can hear your howls of protest, but remember these numbers cover what we typically see across a large population. Owners invariably think of their pampered, ancient kitties and claim that these numbers are way too low, but you can’t forget to include the unfortunate ones that died early from disease or accident.
Here’s a good example. My kitty, Keelor, is still going strong at 17 (knock on wood). He came from a litter of four, one of whom died when he was only a few months old. His sister was euthanized just last year at 16, but his other brother died at a relatively young age (around 10, if I remember correctly) from necrotizing pancreatitis. So if you look at the litter as a whole, they will fall on the low end of that 10 to 15 year range, despite Keelor’s and Scout’s longevity.
The oldest cat I ever had the privilege of knowing was 25. Rosie had lived with her owners ever since she was a kitten, and they didn’t seem the boastful type, so I believed them. Plus, Rosie looked 25 when I knew her! She was a calico domestic long hair, probably a little Persian thrown in there because she had a face like an Ewok. I can still picture her fur sticking up every which way around her pursed little old lady face.
I was her doctor at the end of her life when she was dealing with chronic kidney failure. She probably weighed about four pounds, had no teeth, and would have walked with a cane if she could. She still had a lot of fight left in her though. We even managed to get her through a particularly nasty kidney infection with a course of imipenem (an intravenous antibiotic reserved for the worst of the worst) and bought her another six months of good quality of life. I remember her owners carrying her into the clinic on her pillow to begin this treatment. She was the queen and knew it.
I hope I have half of Rosie’s spunk when I’m her "age" … which would be 116 by my calculations!
Dr. Jennifer Coates