Chihuahua DO attack frequently. But what is there to report? Officer, it was horrible. He left marks in my new Bruno Magli shoes? Even toddlers can fight off a Chihuahua; the mouth is so small it can't do much damage and a plastic bandage usually suffices.
Pit bulls and similar dogs can do a lot of damage due to the size of their mouth and the pressure exerted by their jaws. The point of this story is that the dog who was taken in was not guilty of any violent behavior.