The closed circuit gas anesthesia system includes an absorption chamber for removing carbon dioxide from air exhaled into a mask. This air can then be recycled back to a breathing bag for rebreathing, thus saving on the quantity of gas anesthetic agents, and medical air or oxygen needed.

Excess pressure in the breathing bag is released through a pressure valve, which must be connected to an exhaust from the room.

Animals weighing over 7 kg have sufficient tidal volume to successfully operate the check valves in a closed circuit system. Masks and Endotracheal tubes are available for closed circuit systems. Any system capable of closed circuit operation can also be used in an open circuit configuration. Oxygen low-flow flowmeter or nitrous oxide flowmeter add-on available.