I'm breaking my 10week whippet pup to them now. Got a bowl of milk and chucked them down. It was fine. My pup doesn't want to kill them, just play. I let them together and then tap her when se jumps on it. Left her with my job today and he took a bit of stick then bit her. She left well alone after that. I'm happy the ways Shea getting with them now. Don't know about terriers though, maybe need someone more experienced to help you if the dogs actually trying to kill them