Wow, that is strange Mite, usually males will fight males or females will fight females or unless he tried to create puppies then the female may snap at him. But, this I believe is very odd behavior and most likely a pyschological problem or the owner has been training it to fight. Some peoplewill try teaching their dog most anything.If that is the case maybe that is why the tail was still wagging ?The dog thought that it was doing what the owner wanted it to do ?