Many dog behaviors are biased according to breed. We know that, right? As a general rule, purebred… Hunters want to hunt. Guards want to guard. Fighting breeds want to fight. This becomes a problem when you get the idea that training can override these behavioral scripts. (Even mixed bred dogs have certain biological tendencies.) Then you’ll see that wonderful concept called instinctual drift. Look up instinctual drift… What you might suppress for a while will eventually be defeated to some degree by breeding. There are a lot of board and train companies out there using e-collars, or even all positive methods, and slick marketing to say they can fix any behavior. In the short run, it will appear so. In the long run, unsuspecting pet owners might find those promises not working out so well.