Studies on the pathogenesis of pseudorabies in domestic cats following oral inoculation

Domestic cats were inoculated orally with an Iowa isolate of pseudorabies virus. Several cats were killed at intervals of one day and tissues were examined virologically and histologically to determine the initial sites of virus penetration and replication and to evaluate the pathways traveled by the virus from the mouth to the central nervous system. Lesions were consistent in the tonsils, along the pathways of the sensory branches of the ninth and tenth cranial nerves, the tractus and nucleus solitarius and the area postrema in the medulla. Less consistent lesions in the ganglia and nuclei of the fifth cranial nerve indicated a lesser role for the passage of virus via this nerve. Nervous lesions consisted of multifocal to diffuse microgliosis, mononuclear perivascular cuffing and a mononuclear inflammatory cell infiltration with a variable number of neutrophils occasionally forming microabscesses. Virus isolations correlated well with microscopic lesions. Ultrastructurally, virions were observed within the nucleus of the neurons in the medulla. Clinical signs were similar to those previously reported. Pruritus was consistently absent. Virus was isolated consistently for the first two or three days postinoculation from oral and nasal secretions but not from secretions after three days.