Neuronal Vacuolization in Feline Panleukopenia Virus Infection

Feline panleukopenia virus (FPV) infections are typically associated with anorexia, vomiting, diarrhea, neutropenia, and lymphopenia. In cases of late prenatal or early neonatal infections, cerebellar hypoplasia is reported in kittens. In addition, single cases of encephalitis are described. FPV replication was recently identified in neurons, although it is mainly found in cells with high mitotic activity. A female cat, 2 months old, was submitted to necropsy after it died with neurologic deficits. Besides typical FPV intestinal tract changes, multifocal, randomly distributed intracytoplasmic vacuoles within neurons of the thoracic spinal cord were found histologically. Next-generation sequencing identified FPV-specific sequences within the central nervous system. FPV antigen was detected within central nervous system cells, including the vacuolated neurons, via immunohistochemistry. In situ hybridization confirmed the presence of FPV DNA within the vacuolated neurons. Thus, FPV should be considered a cause for neuronal vacuolization in cats presenting with ataxia.