Necrotizing Tracheobronchitis Caused by Aspergillus fumigatus in a Cow.

This report describes a case of tracheobronchitis caused by Aspergillus fumigatus in a cow. A 4-year-old Jersey cow was submitted for necropsy examination. Grossly, the mucosa of the trachea and bronchi was diffusely reddened and was covered by a moderate amount of yellow, caseous material, sometimes with small foci of grey 'cotton-like' appearance, suggestive of filamentous fungus. Microscopical analysis of the trachea and bronchi showed marked diffuse mucosal and submucosal necrosis with a large amount of cellular debris, fibrinous exudation and inflammatory infiltration dominated by macrophages and neutrophils. There were large numbers of septate fungal hyphae with acute bifurcation angles and conidia and vesicles typical of Aspergillus spp. that were stained by the Grocott method. A. fumigatus growth in mycological culture from the trachea and bronchi was confirmed by molecular identification. Tracheobronchitis caused by A. fumigatus infection in cattle is poorly described and requires further research to improve the therapeutic management of the disorder.