Lung tissue from a mature Barn Owl. The history on this animal is pretty minimal: the bird was found dead one morning at someones property. The fish and wildlife service was called, and upon examining the owl found no gross abnormalities (besides being dead!) The animal was sent our way for a necropsy - the animal equivalent of an autopsy. The owl’s lungs were found to be very dense on palpation….which is never a good things as they should full of air! Specimens were collected for histologic evaluation…
….and the lungs were found to be completely colonized by fungus! Hence the firmness. The above picture shows numerous blue-purple hyphae (easy to see on the bottom left) along with these very large, fruiting body structures! The fruiting bodies look like the Starship Enterprise :-P These structures are actually termed conidiophores, which are comprised of conidia (the tiny dots). Conidia are variants of spores.
Diagnosis: Aspergillosis (presumed). Many avian species are susceptible to primary and secondary fungal infections….and one of their biggest nemeses are Aspergillus species. The organism has been responsible for large die-offs of water fowl throughout the Pacific Northwest over the past decade….and was no doubt the cause of this owl’s death.