CASE REPORT: PROLIFERATIVE AND NECROTIZING OTITIS EXTERNA IN A CAT

Abstract

An 8-month-old intact female shorthair domestic cat was referred to the National Chung Hsing University Veterinary Medical Teaching Hospital for uncontrolled chronic otitis in both ears. The affected ears revealed purulent discharge, erosion with bleeding and brownish-black proliferative tissue in the opening of both ear canals. Cytological examination of the discharge revealed the presence of gram-positive coccoid bacteria. We carried out histopathological examinations of biopsies obtained from friable and proliferative tissues of both ears. Based on the clinical and histopathological characteristics, proliferative and necrotizing otitis externa (PNOE) was diagnosed. Treatment was initiated with a combination of twice-daily application of 0.1% tacrolimus ointment and a once-daily otic lotion containing hydrocortisone aceponate, miconazole nitrate and gentamicin sulfate following the administration of once-daily anti-bacterial flush which contains tromethamine, edetate disodium dehydrate (EDTA) buffered to pH 8 with tromethamine hydrochloride and deionized water. The antibiotic ear lotion was withdrawn in the absence of purulent discharge in both ears after 11 weeks. Most proliferative lesions resolved after 17 weeks, and we tapered the dosage of 0.1% tacrolimus from once daily to once weekly during the year follow-up period. However, in our case, partial remission of PNOE was observed with the application of a combination of 0.1% tacrolimus ointment and a commercial ear lotion. The cat was healthy and had a good quality of life. To our knowledge, this is the first report of PNOE in a cat in Taiwan.