Why Can a Small Dog Intimidate a Large Dog?
If your large dog suddenly encounters a much smaller but aggressive dog, and seems to be intimidated by the small animal, there is a very good reason for that. Your Doberman, or German Shepherd, etc. is not a wimp. Far from it. Your dog could kill the small dog with a simple shake of its neck. Your dog is simply obeying its ancient instinct (from when its kind were gray wolves) never to hurt a puppy. Remember, we engineered small dogs; they do not occur in nature. So the larger dog is confused, and is further confused by the fact that the smaller dog is acting aggressively. This is something a wolf puppy would never do, or she or he would be put in his/her place by an adult quickly. So please don't call your big dog names. He or she is only being a good citizen in his/her mind. The proper response is to praise your large dog, and then turn and walk in another direction. (Source: Desmond Morris, Zoologist and author of, "The Naked Ape."