Abstract: A structure permitting pets separate passage between a household and the out-of-doors, comprising a succession of weathertight doors which the animal must traverse independently and consecutively and for which the household pet must be trained. An animal approaching the structure from the outside is not exposed to any draft or odor emanating from the interior of the house and, furthermore, is initially presented with a door that only opens backward toward itself and up; consequently, strange animals--those not trained to the structure--are not induced to enter.