Aspergillus fumigatus is a saprophytic fungus that affects dogs in many geographic locations throughout the United States, including Nebraska. Sinonasal aspergillosis typically occurs in dolichocephalic breeds, affecting both nasal passages and paranasal sinuses. Infection routinely causes atrophic rhinitis and subsequent mucopurulent-to-hemorrhagic nasal discharge. Infection commonly manifests initially as unilateral disease, but without proper identification and treatment, bilateral disease frequently occurs. Dogs with nasal aspergillosis frequently have depigmentation of the nares, pain on palpation of the nasal cavity and may be systemically ill with varying degrees of lethargy, and weight loss.