the base panel 90 may be carpeted or otherwise embellished for comfort of the pet the portal 20 includes the tubular duct 94 complementary to the portal opening having an inner flanged mounting panel 96 secured to an interior wall of the structure and an outer flanged mounting panel 98 secured to the rear wall 56 the door 40 is pivotally suspended from the top or the duct 94 and covers the opening in a normal closed position to isolate the litter box from the interior of the structure while permitting the pet to pivot the trap door readily and sufficiently to gain entrance to and egress therefrom the door 40 additionally functions as a weather and odor barrier between the interior and the enclosure referring to fig6 the litter box container comprises a rectangular base 100 surrounded by peripheral walls 102 defining an upwardly opening receptacle for holding a desired amount of litter material 32 the walls 102 are closely adjacent the front wall and side walls and have a slight clearance relation therewith the rearward peripheral wall is provided with a rearwardly projecting lip 104 overlying the base panel 90 and establishing an affirmative stop in the normal position referring additionally to fig5 a pair of laterally extending support shafts 110 are attached at proximal inner ends to the container the shafts 110 are rotatably journaled at midportions in apertures in.