My Dad got charged by a navy security dog who was released into the secured area too early. He became aware of the dog because the handler was running behind him yelling at the dog. The dog (a German Shepard) jumped at him and Dad stuck his hand out. He grabbed the dog by the jaw and broke his neck. The handler then proceeded to threaten him for killing the dog. This happened a while back, but he still has a scar on the web of his hand from the dog biting down right before he twisted.
*Opinion worth what you paid.