Sudden death of a Siamese crocodile (Crocodylus siamensis) due to systemic aspergillosis.

A 4-year-old female Siamese crocodile (Crocodylus siamensis) housed at a zoo died without any prior clinical signs. During necropsy, numerous scattered, well-demarcated, yellowish-white, firm nodules were observed throughout the liver and lungs. Microscopic examination with periodic acid-Schiff staining revealed granulomatous inflammation in the liver and lungs. Liver granulomas were characterized by the presence of a connective tissue barrier and hyphae, and the centers of the granulomas showed signs of necrosis. Lung samples showed characteristics similar to those observed in the liver samples. The fungus was identified as Aspergillus fumigatus based on its appearance on Sabouraud dextrose agar, microscopic examination with lactophenol cotton blue staining and genetic sequencing. Therefore, zoo veterinarians should pay close attention to fungal infections in captive animals.