THE LIFE STAGES AND AGES OF THE CAT
The ages and life-stages of cats have been redefined in recent years. Cats are considered to be senior/elderly once they reach 11 years of age. From 15 years and upwards they are considered geriatric. However, just as in humans, there is no fixed rule and many of the cats that are older than 15 years can be surprisingly fit and healthy.
When caring for older cats it sometimes helps to appreciate their age in human terms.
Websites that may be of interest:
https://healthypets.mercola.com/sites/healthypets/archive/2014/09/22/senior-cat-care.aspx
https://www.winnfelinefoundation.org/