Abstract
The gastrointestinal form of Isospora is well described in Passeriformes, but there are few reports of the visceral form of Isospora. Therefore, to evaluate the visceral form of Isospora in canaries with "black spot" syndrome, gastrointestinal contents were prepared from 50 canaries that were lost and appeared with black spot under the skin of the abdomen. At the same time, tissue samples were collected from visceral tissues. After preparing the samples, the oocysts were counted in the digestive contents. A total of 7 canaries out of 50 canaries showed oocysts in their feces. Following the identification of infected birds, histopathological sections were prepared from their visceral tissues. Visceral tissues included the heart, liver, and intestine. Inflammation and hyperemia were seen in the microscopic view of the heart, but no developing stage of parasites was seen. The liver showed inflammation as well as the asexual reproductive stage of the parasite. The asexual reproductive stage of the parasite was also observed in the intestine. Therefore, Isospora seems to be involved in the syndrome of black spot in canaries by causing gastrointestinal and visceral lesions.