I know this is a two year old thread but: I have a chijuajua and the vet told me that if I wanted to have 24 hour dog doors, the dogs would have to go into an area with 360 degree protection. I have 6 foot wood fences and 10,000 square feet of hawk net or orchard net, over my house and covering the front and back dog yards. The net comes down to the wood fence to keep cougars and coyotes out, the birds, squirrels and racoons mange to still pass through the net just fine but no hawks or eagles or osprey. My dogs get up in the night and go out the dog door in the bedroom, the other is in the kitchen and they can run around to the other door outside.