<P> Aging in dogs (Canis lupus familiaris) varies from breed to breed, and affects the dog's health, physical ability and life expectancy . </P> <P> As with humans, advanced years often bring changes in a dog's ability to hear, see and move about easily . Skin condition, appetite and energy levels often degrade with geriatric age, and medical conditions such as cancer, renal failure, arthritis and joint conditions, and other signs of old age, may appear . </P>

A 12 year old dog is how old in human years