Here in Vermont they don't allow someone to shoot a dog in revenge "after the fact". Yes the cops dog was attacked, but the fight had ended. He went into his house out of anger, got a .45 and shot the neighbors dog out of revenge. No sweeping this under the table like in other states! There is a lot of leeway for self-defense here in VT for civilians and and police, but not after the threat has ended!

http://www.wcax.com/Global/story.asp?S=10421204