We have a 3 year old mini daschund. He was spade over a year ago now. He barks at "intruders" in our home. Until today he has never bitten anyone. What's that saying, "NEVER say Never...ugh" What do I need to do to correct him and can I trust him with incoming guests. Heck for that matter can he be trusted to take a leak outside? Again I say, "UGH!"