Malassezia species are a common cause of otitis externa in dogs. Ketoconazole is a systemic treatment option for yeast otitis. In this study, the authors compared the in vitro activity of a commercial ear rinse containing tromethamine, ethylenediaminetetraacetic acid, and benzyl alcohol (T8 solution Ear Rinse, IVX Animal Health; alone and with the addition of 0.1% ketoconazole. Nineteen field strains and 1 control strain were incubated for 0, 15, 30, 45, and 60 minutes in T8 solution, T8 with 0.1% ketoconazole, or water. Malassezia growth significantly decreased at all time points in T8 solution plus ketoconazole when compared with water or T8 solution alone. Study funded by IVX Animal Health Inc., St. Joseph, Missouri

COMMENTARY: Yeast otitis is a common problem in atopic and seborrheic dogs. It is also frequent in dogs that swim or have their ears regularly groomed. The pruritus can be severe, and some dogs even develop otitis media secondary to chronic otitis externa. The findings of this in vitro test are promising for the product as yet one more option for long-term management or as adjuvant management of dogs with yeast otitis. This would be the first otitic/topical product to contain ketoconazole.

In vitro activity of an ear rinse containing tromethamine, EDTA, benzyl alcohol and 0.1% ketoconazole on Malassezia organisms from dogs with otitis externa. Cole LK, Luu KH, Rajala-Schultz PJ, et al. VET DERMATOL 18:115-119, 2007.