Blue, a 6-year-old castrated Catahoula hog dog presents with chronic left epistaxis, mucoid left nasal discharge, foul odor, and nasal planum ulceration. What is the top differential diagnosis?

• A. Aspergillosis
• B. Nasal neoplasia
• C. Fungal granuloma
• D. Chronic rhinitis

Answer: (A)

Aspergillosis. When a dog has chronic unilateral nasal disease with epistaxis, mucoid discharge, a foul odor, and ulceration of the nasal planum, a fungal infection of the nasal cavity—classically Aspergillus fumigatus—becomes the leading consideration. This fungus tends to cause destructive, localized disease in one side of the nose, producing necrosis that results in foul-smelling discharge and ulceration. The odor and tissue destruction fit with a necrotizing fungal infection more than with simple chronic rhinitis, which is usually bilateral and less destructive, or with nasal neoplasia, which can be unilateral too but often lacks the characteristic necrotic odor and nasal planum ulceration early on. A fungal granuloma is possible but less typical than Aspergillosis in this pattern. Confirmation comes from imaging showing turbinate destruction and tissue biopsy or culture identifying fungal elements, guiding targeted antifungal therapy.