Abstract
Two captive Keel-billed toucans and a Chestnut-mandibled toucan in another zoological garden died suddenly without any pre-existing symptoms, and three months later, a Japanese squirrel died of diarrhea. All these animals showed necrotic enteritis and multifocal necrosis in the liver and spleen with Gram negative bacilli. The bacilli showed strong positive immunolabeling for Yersinia pseudotuberculosis O4 in the Keel-billed toucans, Y. pseudotuberculosis O2 in the Chestnut-mandibled toucan and Y. pseudotuberculosis O1 in the Japanese squirrel, while Y. pseudotuberculosis 4b, 2b and 1b were respectively isolated from the lesions. To our knowledge, this might be the first reported case of fatal yersiniosis in a Japanese squirrel in the world as well as in toucans in Japan.