Orchitis in a Cat Associated with Coronavirus Infection

A case of severe, pyogranulomatous and necrotizing orchitis in a cat, which later succumbed to systemic feline infectious peritonitis (FIP), is described. The 3·5-year-old cat, positive for feline immunodeficiency virus infection, presented with a left testicular enlargement. A few months after castration the animal was humanely destroyed due to declining health. Post-mortem examination revealed inflammatory lesions in abdominal organs and in the brain compatible with FIP. Infection was confirmed with a reverse transcriptase–polymerase chain reaction test and by immunohistochemical demonstration of coronavirus antigen in the affected tissues, including the left testicle. FIP is usually a systemic disease. However, lesions and presenting clinical signs in a single organ system such as the brain are not uncommon. The results of this case study indicate that orchitis, although rare, should be on the list of lesions of FIP.