The typical lifespan of dogs varies considerably by breed.
For example, many giant dog breeds (such as Great Danes) average only 7 or 8 years, while some small terrier breeds, or toy breeds might live as long as 20 or above. The average lifespan for mixed-breed and midsize dogs is about 13 to 14 years.
The longest-lived dog with reliable documentation died at 29 years and 27 days, the breed of the dog was an Australian cattle dog and it lived in Virginia, USA, the date of death was in 1939.
The oldest currently living dog is from Canberra, Australia and is now 27 years old. Although the lifespans of all living species are mostly uncontrollable, one can significantly extend a dog's life by feeding it the right kinds of foods, giving it regular exercise, treating its diseases, caring for its special needs and giving it love and comfort.