My old dog would bark at fire crackers. Nothing ever seemed to scare him.
He would also attack if someone had a toy gun. No idea where he learned that as he was still pretty young when I found him.
My brothers dog, on the other hand, would hide from everything. And she was the bull dog.
I never thought about dogs running away on the 4th, but it makes sense and is a good tip. Pet owners need to understand their pets and know how they will react. Too many don't.