I often wonder why fighting breeds are not considered dangerous weapons

I often wonder why fighting breeds are not considered dangerous weapons. I can set my 870 12ga. shot gun near the back door the mail comes no one gets hurt, the neighbor's children play no one gets hurt, the lady down the street walks by with Her dog no one gets hurt. Not once did the gun load its self and chase someone down and kill or severely hurt anyone. However humans have bred dogs designed to kill and maul and many act as it is just an accident when they maul and kill !! (posted by " D-Man")