It varies, but cats and small dogs are generally considered geriatric at the age of 7. Larger breed dogs tend to have shorter life spans and are considered geriatric when they are approximately 6 years of age. Owners tend to want to think of their pet's age in human terms. While it is not as simple as "1 human year = X cat/dog years", there are calculations that can help put a pet's age in human terms:
Cat years - Human years
7 45
10 58
15 75
20 98
Dog years - Human years (*dog size lbs)
7 Small – Medium: 44-47
Large – Very large: 50-56
10 Small – Medium: 56-60
Large – Very large: 66-78
15 Small – Medium: 76-83
Large – Very large: 93-115
20 Small – Medium: 96-105
Large: 120
*Small: 0-20 lbs; Medium: 21-50 lbs; Large: 51-90 lbs; Very large: >90 lbs
The oldest recorded age of a cat is 34 years. The oldest recorded age of a dog is 29 years.