My daughter and boyfriend rescued a 1-1 1/2 year old bulldog named Bluto from Chinese meat market. He is so good except that he is obviously not house trained from spending most of his life confined to a cage. He does use pee pads at times and will pee outside but not poop. She has a crate for him but if left in it while they work he will use it as his bathroom. They have 2 other dogs and they are trained but they are having a difficult time with Bluto. Please advise.