Listeric meningoencephalomyelitis in a cougar (Felis concolor): characterization by histopathologic, immunohistochemical, and molecular methods.

Listeria monocytogenes has been recognized as an important food-borne pathogen in animals. Records of the disease caused by this bacterium in large felids are, however, rare. The nervous form of listeriosis was diagnosed in a 12-year-old male cougar (Felis concolor) with a several-day history of neurologic disease characterized by excess salivation, head pressing, and circling that progressed to recumbency and death. Microscopically, the main alteration in the brain and spinal cord was a variably severe meningoencephalomyelitis composed mainly of mononuclear cell aggregates with fewer neutrophils. L. monocytogenes was isolated from the brain by microbiological culture, and L. monocytogenes antigen was detected in formalin-fixed, paraffin-embedded sections of brain and spinal cord by immunohistochemical analysis. On the basis of the nucleotide sequence of the 16S rRNA gene, the isolated strain was determined to be serotype 1/2a. Food-borne transmission of the bacterium was suspected, but food was not available for testing.