An insufflator assembly, comprising: an insufflator comprising a delivery component (1) for delivering powder into an airway of an animal, a metering component (3) for providing a dose of powder (P) to the delivery component (1) and an inlet for receiving a stream of gas; and means for providing a stream of gas to the inlet of the insufflator so as to carry the dose of powder (P) into the airway of the animal, the means comprising a chamber (45) of a predetermined volume for containing gas at a predetermined pressure above atmospheric, a pressurized gas source (9) for providing gas of a predetermined pressure to the chamber (45), a first valve (47) for selectively connecting the chamber (45) to the pressurized gas source (9) and a second valve (49) for selectively connecting the chamber (45) to the inlet of the insufflator.