"HEY <anyone in house, assuming they weren't in the room though>, IS THIS YOUR DOG?"
Tell the dog to leave kindly, hoping the dog can understand language spoken to him and can't just mimic Robert De Niro, or give it to a friend that likes dogs AND Robert De Niro.
I don't dislike dogs, I just don't want one (looking, touching, bearing it's teeth or staring at me and leaving hair all over the place).