“I need to know what kind of dog it was before I decide if this upsets me.”
What the hell difference does it make what kind of dog it was? It was in a back room by itself minding its own business.
You don’t know that. It could have attacked the police. Just because it is a family dog doesn’t mean that it’s a friendly dog.
Unless you are the policeman that shot the dog, or a reincarnated version of the dog itself, I doubt you can speak for what the dog was doing.