Seventeen Cases of Fungal Otitis Externa in Dogs and Cats

BACKGROUND: Otitis externa (OE) is common in dogs and cats. Fungal OE (FOE) caused by non-Malassezia species fungi is relatively uncommon. Comprehensive information on clinical manifestations, risk factors and breeds or species predispositions remains sparse. In this case series, we describe 17 companion animals in China with FOE. OBJECTIVES: To describe the clinical signs, potential risk factors and treatment of FOE in dogs and cats. ANIMALS: Seventeen cases: four dogs and 13 cats. MATERIALS AND METHODS: Retrospective review of medical records of cases presented to dermatology specialty practices for OE between 2022 and 2024 was performed. Records with positive fungal culture results were included. Case demographic, diagnostic and treatment information was extracted. RESULTS: Aspergillus spp. was isolated from 13 animals (three dogs, 10 cats), Microsporum canis from one dog and two cats, and one cat had a mixed infection with M. canis in the left ear and Aspergillus spp. in the right. The most common clinical signs were excessive cerumen and pruritus. Of 16 cases that received antifungal treatment, 13 received combined oral and topical therapy, and three received only oral therapy. CONCLUSIONS AND CLINICAL RELEVANCE: Aspergillus spp. or dermatophyte infection should not be overlooked in cases of chronic or recurrent OE. Cytological examination of exudates and fungal culture are useful for establishing the diagnosis of FOE. Larger prospective studies are needed to elucidate risk factors and appropriate treatment for FOE.