Whenever you ask someone how old their dog is in human years, they are likely to figure it out based on the old formula of 1 year for a dog equals 7 human years. This isn't really true though. It is actually based more on the kind of dog it is. Most of us know that small dogs live much longer than big dogs, with 10 years for an Irish Wolfhound or Great Dane being old age. But for a much smaller dog, 10 years is more like middle age and they have many more years to go, as long as you give them a reasonable amount of exercise and a diet better suited for seniors. I've had Pomeranians, mostly, and my Kameko, at 12 1/2 is still playful and does a 2 mile walk, with hills, without barely breaking a sweat. When a friend, a few months ago, asked us her age we said, 11. He asked, 11 months? At the time she was running around his office, barking, and greeting everyone who paid her just the tiniest bit of attention.
As for cats, since there isn't the size difference thing that there is with dogs, there is a formula that pretty much works for determining their age. Once cats are into young adulthood, say two years old, you can add four years for every year of life so that a four-year-old cat will be about 32 human years and an eight-year-old cat will be about 48 human years. And as with dogs, keeping your cat on a healthy diet with minimal treats and a fair amount of exercise will help them survive into old age (that's 20 years, or 96 in human years).