Distinct life stages (age groups) in cats are not well defined, in part because individual animals and body systems age at different rates, a process that is influenced by many factors. These guidelines follow one convenient classification (see box below). These age designations help to focus attention on the physical and behavioral changes that occur at different stages (eg, congenital defects in kittens, obesity prevention in the junior cat). It must be recognized, however, that any age groupings are inevitably arbitrary demarcations along a spectrum, and not absolutes.

These guidelines follow a convenient life stage classification developed by the Feline Advisory Bureau and adopted in the recent AAFP Senior Care Guidelines.^4,5 Six age groupings are defined, from kitten through to geriatric.