If you MUST have a purebred, choose one with three generations of obedience champions - it will be bred to cooperate and should be healthy. The good thing about purebreds is that you have some idea of purpose bred dogs behavior. Unfortunately breeders often choose for looks, not function or disposition. And here's the kicker... Dogs who are born with genetic malformations can get reconstructive surgery, compete in shows and go on to win at Madison Square Garden and Crufts. These will be the favored bloodlines and taint top breeding stock - forever. Like racehorses that grow fast, run fast and whose bones snap - they can no longer do what they were bred to do. My greyhound is off the track, kills coyotes and loves my bunnies. My Great Pyrenees (rescued) guards my livestock and my... erm.. Catahoula/Lab/Heeler does NOT chase my chickens, sleeps with my cats, makes me laugh and is a great handicapped assistance dog.