Abstract: The ventilated cage and rack system is provided having a plurality of shelves. An exhaust plenum is removably affixed to each shelf for providing air to predetermined air positions along each shelf. At least one cage is provided for housing at least one animal therein, the cage is a cage level barrier having a gas impermeable portion having upstanding sidewalls and a filter positioned on the side wall. A removable cage canopy is mounted to each shelf for guiding the cage toward the predetermined air position and containing air escaping from the filter bonnet within a confined area for removal.