A whole body plethysmograph has been incorporated in an apparatus for exposing dogs individually to radioactive aerosols. This makes it possible to monitor the dog's respiratory pattern during the exposure without the use of any respiratory masks or valves. After three different transducer systems were evaluated for use with the plethysmograph, the flow rate transducer was chosen for several reasons including the fact that this system produces inspiratory and expiratory flow rate data as well as tidal volume and respiratory rate information. The aerosol is continuously produced and drawn past the dog's nose during the exposure period and provision has been made for quantification of the aerosol in terms of concentration and particle size distribution for each experiment. External contamination of the dog is minimal since only the nostril area is uncovered within the aerosol exposure chamber. Pertinent design and calibration features are discussed.