AAFP/AAHA feline life stage guidelines.
Cats age rapidly in their first two years: year 1 ≈ 15 human years, year 2 ≈ 24 human years. After that, each cat year ≈ 4 human years. The AAFP defines 6 life stages: Kitten (0-6 mo), Junior (7 mo-2 yr), Prime (3-6 yr), Mature (7-10 yr), Senior (11-14 yr), Geriatric (15+). Indoor cats typically live 12-18 years; outdoor cats average 2-5 years due to hazards. The oldest recorded cat, Creme Puff, lived to 38 (≈ 168 human years). Regular vet checkups become increasingly important after age 7 — twice yearly for senior cats. Common age-related conditions: kidney disease, hyperthyroidism, diabetes, and dental disease.