Production of Experimental Lobar Pneumonia in the Dog. ∗

Abstract

Until the work of Cecil and Blake 1 lobar pneumonia had not been produced constantly and successfully in the lower animals. These authors employed the Macacus syrichtus, a Philippine monkey which is apparently more susceptible to the pneumococcus than the other varieties. Their method consisted simply of intratracheal injections of small quantities of pneumococci. The disease produced and the lesions observed corresponded closely with lobar pneumonia in man. However, the subsequent employment of this method with other species has failed to produce lobar pneumonia apparently because they were more resistant to the pneumococcus than the Macacus syrichtus which unfortunately is no longer allowed to be imported into the United States. Others working with the dog have found that in order to produce pulmonary infection with the pneumococcus, not only must the infecting agent be implanted far down in the bronchial tree but the inoculum must be massive. Lamar and Meltzer 2 using this method were successful in producing in some of their animals lobar consolidation and a disease resembling an abortive lobar pneumonia. But the infected animals which lived longer, died within 2 to 4 days with bacteremia and pyemic complications without true consolidation of the lung. Many of their dogs escaped infection. More recently Coryllos and Birnbaum 3 have employed a modification of this method, spraying large quantities of pneumococci culture into the lung through a bronchoscope either with or without subsequent occlusion of the main bronchus. This resulted either in a transient infection or a widespread pneumonia accompanied by atelectasis with an ensuing generalized infection and fatal termination.

Thus the methods previously used in an attempt to produce lobar pneumonia in dogs, not only have failed to induce the characteristics of the disease as seen in humans, but have employed a dosage which is enormously greater than could occur in the spontaneous inception of the disease in man.