The average life expectancy of a domestic, indoor cat is 15 years, though cats commonly reach 18 to 20 years old. Feral, outdoor cats have an average life expectancy of approximately six years.
Once a cat is more than 7 years old, some veterinarians recommend annual or biannual checkups. In addition to a physical examination, veterinarians recommend a yearly blood panel, stool exam and urinalysis. The results of these tests reveal kidney, liver, thyroid and intestinal problems. These tests also detect parasites and infection. The three largest health hazards for outdoor cats are parasites, infectious diseases and trauma. Regular veterinarian visits for vaccinations, testing and injury treatment increase a cat's life expectancy.