Abstract
Twenty-nine cases of feline infectious peritonitis were studied histopatho-logically. It was notable that, in most cases examined, there existed degenerative andproliferative changes in the blood vessels of different parts, especially in endothelial andmedial layers of fine and smaller veins or arteries with perivascular infiltration of neutro-phils and mononuclear cells. Every case had varied amounts of ascites and/or hydrothoraxwith fibrinous precipitates covering the entire surface of peritoneal and thoracic cavitiesas well as visceral organs. Metaplasia and hyperplasia with syncytium formation wereremarkable in mesothelial and mesenchymal cells of the peritoneum and pleura. In mostcases multiple necrotic foci with infiltration of neutrophils and mononuclear cells andhemorrhage were seen in the serosa, omentum and mesenteries, and the same lesionsappeared also in the parenchyma of the liver, spleen and mesenteric Nymph nodes of somecases.
