I wonder about that, as well. my dogs have had a charmed life. nice rural area, walks without leads, lots of exercise, hunting, etc. They have also gone through a lot of training…canine good citizen, rally, hunt test. Up until a year ago, it was a rare occasion that the dogs would be left alone at all. That has changed since my husband died, but the rest is still there. My dogs are calm and content more than other dogs of their breed, but when I babysit friends dogs, mostly labs, I can see their dogs relax beyond their normal level if they are here for at least a week.