Distinct mutation in the feline coronavirus spike protein cleavage activation site in a cat with feline infectious peritonitis-associated meningoencephalomyelitis

CASE SUMMARY: This report describes a cat with chronic, progressive, non-painful, non-lateralizing multifocal neurologic clinical signs associated with feline infectious peritonitis (FIP). The cat initially presented as underweight, despite a good appetite, and a complete blood count showed non-regenerative anemia. Three months later the cat was returned having developed ataxia and paraparesis, which then progressed over 2 months to tetraparesis, tail plegia, urinary and fecal incontinence, and titubation. Histologic examination of the tissues with subsequent immunohistochemistry confirmed FIP-associated meningoencephalomyelitis following necropsy. Molecular analysis of the coronavirus spike protein within the tissues identified a specific, functionally relevant amino acid change (R793M), which was only identified in tissues associated with the central nervous system (ie, brain and spinal cord). RELEVANCE AND NOVEL INFORMATION: This case report describes an early presentation of a cat with primarily neurologic FIP, with molecular characterization of the virus within various tissues.