Labrador Retrievers are the healthiest breed of dog. They have a low risk for heart disease and other ailments that affect many breeds such as hip dysplasia or elbow dysplasia. People love Labs for their easy-going, gentle-natured personalities. Labradors make excellent companions for families with children and people with disabilities because of their nature and social attitude. Border Collies Border Collies are the second healthiest breed. They are low risk for cancer and life span is average, but they have a high risk of developing hip dysplasia (a malformation in the ball and socket joint)