I have a Hale doggie door for the past 3 years. http://www.halepetdoor.com/index.asp. Expensive, but worth every penny. Mine is in the exterior wall & comes out in a cabinet in the kitchen. The bottom 2 drawers of the cabinet are false & sealed from the top 2 usable drawers. The dogs make a right turn to get in. The plastic piece next to the door is a blocker to keep the dogs from going in or out.