The Average Lifespan of a Jack Russell Terrier When considering the life span of a Jack Russell terrier, there are many things to consider, including the energy level of the breed. While this breed is small, it is sturdy and will fight against any opponent. Jack Russells can live from 14 to 21 years. If you’re considering getting a Jack Russell, be prepared to make a commitment and care for the dog for many years. In America, the long-legged version of the breed is officially referred to as the Jack Russell Terrier. It is the perfect companion for the equestrian crowd and is the official breed of a Jack Russell.…