Epidemiological data and a score-based study of renal, hepatic and cerebral lesions in feline infectious peritonitis

The study describes the epidemiological and pathological findings observed in a population of cats with feline infectious peritonitis (FIP) and estimated the degree of tissue destruction in the kidney, brain, and liver. A retrospective study was performed to determine the number of cats with a histopathological diagnosis of FIP between 2005-2016, at the Laboratory of Animal Pathology, Universidade Estadual de Londrina. The histopathological alterations in selected organs (brain, liver and kidneys) associated with FIP were described and then compared with a scoring system to estimate the degree of tissue destruction. FIP was diagnosed in 3.7% (19/520) of all cats necropsied during the 11-year period; sexual and breed predominance were not identified. Cats that were less than one-year-old were more frequently diagnosed with FIP. Pyogranulomatous nephritis with vasculitis (94.7%; 18/19), coagulative renal necrosis (84.2%; 16/19), hepatocellular necrosis (57.9; 11/19), and necrotizing leptomeningitis (47.4%; 9/19) were the most frequent lesions observed. Moreover, FIP-associated renal lesions were more severe and frequently observed when compared with those in the brain and liver. It is proposed that necrosis be considered as an important lesion associated with FIP that should be included in the histopathological diagnosis of this disease