To what age can a dog live, and to what human ages do every five years of a dog's life equate?

1 year in dog years = 7 human years

dogs can live 15-20 years

Roughly, 10.5 dog years per human year for first 2 years, then 4 dog years per human year for each year after. http://www.executec.com/age.htm

This particular question has so many variables, that there is no definative answer.

If you take into consideration that a dog can become sexually mature at as early as 5 months old, this alone totally shoots the 7/10 year theory, making it closer to 18-22 years in the first year. Anyone who has lived with an 7-11 month old dog KNOWS they are definately living with a wild-teenager!!

Size would be the other factor. Some of the smaller, toy breeds can live up to 18-20 years, whereas a blue Great Dane may only live 6-7 years.

Health, genetics, environment, nutrition, etc all contribute to the life expectancy of a dog.