Obviously...but an animal trained to fight, is also bred to Never bite it's handler...or humans. The biggest problem those animals have is that they're often not animal socialized....has nothing to do with humans. Can a dog be trained to threaten humans? Sure...and you have to have VERY clear signals so that the animal does not threaten you as well... Most often guard dogs, are not pets...they are working animals. However, any mid to large sized dog can be a potential threat to any human.