Q. I've heard that small dogs live longer than large dogs. Is this true? If so, why?
A. It is true that the small, or toy, breeds live longer. The Chihuahua, for example, has a life expectancy of 16 to 18 years. The larger the dog, the shorter its life. Great Danes rarely live more than 8 years. In the simplest terms, there is less strain on the organs (liver, heart, lungs, etc.) of a small dog to keep it alive and much more strain on those of larger dogs.