The Average Lifespan of Cats vs. Dogs

The average lifespan of a cat living indoors is higher than that of a cat on the street, even if that cat is only on the street part of the time. The average lifespan of a cat has increased dramatically in the past 20 years as veterinary care has become more sophisticated. The average life expectancy for a strictly indoor cat is 12 to 15 years. Many live to be much longer; the oldest cat on record died at the age of "38 years and 3 days," according to the Guinness Book of World Records. A strictly outdoor cat lives less than five years, and an indoor/outdoor cat averages somewhere around eight years.

The consequences of living outdoors is a life fraught with stress, starvation, cruelty, disease and injury; all of which can cause an early death. Cats who live outdoors are subjected to a variety of problems cutting their life expectancy. Cats who live indoors, however, have a relatively stress-free life and all the food they need. More importantly, though, is the fact that if the cat has a problem, the owner usually notices it early and intervenes, a luxury outdoor cats do not have. Though indoor cats have that advantage, cats who go in and out at will are at risk for injury from cars, other animals, cruelty from humans and stranger danger.

Unlike cats, the life expectancy of dogs depends not so much on whether they live indoors or outdoors -- although that does come into play for individual dogs -- as it depends on a dog's size. The great Dane's life expectancy is only about eight years, for instance, while that of a miniature poodle is 15 years. A larger dog's heart has to work much harder to support the dog's organs than that of a little dog. Other factors contributing to a dog's life expectancy is her overall health and lifestyle. An outdoor dog who is under stress most of the time -- due to loneliness, neglect, stresses from extreme weather or teasing from kids, for example -- will most likely die before a dog who is living the life of Riley in a home.

Neutering or spaying a pet may help extend the animal's life span because the surgery drastically lowers the risk of certain kinds of serious health concerns including complications from pregnancy and delivery such as dystocia, and certain cancers that affect the mammary glands and reproductive organs. It virtually eliminates the risk of pyometra and prostate disease. Trap, neuter and release programs for cats notwithstanding, stray cats and dogs are not usually sterilized, elevating the risk for a life-shortening illness.

So, what is the life expectancy of cats vs. dogs? Since the average lifespan of a cat is 12 to 19 years, and the dog with the shortest lifespan lives only an average of 8 years, all things being equal, cats live longer than dogs.