What age is "old"?
What age qualifies a pet as geriatric? Many people have heard the ratio of dogs aging 7 human years for each calendar year, but the truth is that even within the canine family, larger dogs age much faster than smaller dogs. For small cats and dogs, many consider 11.5 years of age geriatric, while larger breed dogs are considered "old" much younger, at 9 or 10 years of age.
I think the more relevant question is not how OLD the pet is, but how the pet IS. Old age is not a disease, but problems arising from advancing age can cause discomfort, disability, and sometimes death. Some of the challenges of advancing age for a pet include: vision and hearing changes, skin changes, mobility changes, restlessness at night, and changes in the immune system that make make the pet more susceptible to infections. While none of these changes are reversible, there are certainly things that we can do to make our pet's older years more comfortable, such as providing ramps for arthritic pets or placing yoga mats on top of slippery "ice rink" surfaces.