Abstract
Airborne dust particles are an important vehicle for potentially pathogenic micro-organisms, which may thus spread from cage to cage. The dust itself may also be irritant to the respiratory tract, and produce a condition favouring the establishment of respiratory disease.
A method has been devised of ventilating each cage in an animal room with a constant stream of air that is virtually free of particles, whether from another cage or from any other source. This method entails the use of a filter rack, which is simple and inexpensive, and so far appears to afford considerable protection. In effect, it places an air barrier round each cage.
The complex aetiology of respiratory disease in the rat and the relevance of a filter rack to its control are discussed. The essential features of the design of a filter rack are given.