A five-month-old, male Domestic Korean shorthair was referred to our hospital with a history of lethargy, anorexia, and globoid cardiac silhouette on thoracic radiography. Physical examination showed dehydration and anemia was revealed on blood analysis. On thoracic radiography and echocardiography, the patient showed pericardial effusion and ultrasound-guided pericardiocentesis was performed. A Rivalta test of the pericardial effusion showed a positive result. As the patient had recurrent pericardial effusion, pericardiectomy was performed. He was tentatively diagnosed with wet form feline infectious peritonitis (FIP) and treated with Polyprenyl immunostimulant (PI). Neurological signs were eventually seen and he was euthanized. Histopathologic changes with markedly expanded neutrophils, lymphocytes, plasma cells, and macrophages with fibrous connective tissue and collagenous fibers were detected. Immunohistochemistry for FIP antigen was performed and results showed FIPV-positive multifocal aggregates of cells. Pericardial effusion is an atypical condition in cats with FIP, but can be presented. This case report describes FIP with pericardial effusion in a cat, in which definitive diagnosis of FIP was done using biopsy via pericardiectomy.

Keywords: feline infectious peritonitis (FIP), pericardial effusion, pericarditis, pericardiectomy