Parainfluenza type II infection in dogs. A model for viral lower respiratory tract infection in humans

To determine if parainfluenza type II (P2) virus infections in dogs could be used as a model for viral airways disease in children, we studied pulmonary function and histopathology in 12 P2-infected and 8 control beagle dogs. Ten infected animals developed symptoms of cough and rhinitis within 9 days of virus exposure. Histologic changes in infected dogs included ciliated epithelial denudation and peribronchial and peribronchiolar lymphocytic infiltrates involving airways of all sizes; most notably, 19 to 57% of nonrespiratory airways less than 1 mm in diameter were affected. Two weeks after the onset of symptoms, infected dogs were asymptomatic, but they had lower functional residual capacities (p < 0.05) and lower specific lung conductance (p < 0.05) than control dogs. Additionally, dynamic compliance did not increase with lung growth in infected dogs as it did in control dogs. These results suggest that parainfluenza type II infections can be experimentally produced in dogs (without concomitant bacterial infection), that these viral infections are similar to human viral lower respiratory tract illnesses, and that such viral infections may alter lung development in rapidly growing dogs.