One embodiment may take the form of a litter box having a base portion having a floor and a plurality of walls extending in an upward direction from the floor. The litter box may also have a cover portion having a ceiling and a plurality of walls extending in a downward direction from the ceiling. The base portion and the cover portion may combine to define an inner cavity. The litter box may also include a circulating filter in communication with the inner cavity of the litter box and the circulating filter may be configured to filter air from within the inner cavity of the litter box.
