The records of 60 dogs that had a resection of the lateral wall of the vertical ear canal (Zepp) were examined. The surgical outcomes were evaluated in association with the following variables: breed, sex, age of onset of the otitis externa, duration of the disease before the surgery was performed, treatment received for the otitis externa, the status of the ear and tympanic membrane at the time of the surgery, the culture results, and concurrent medical problems. The outcome of surgery was acceptable in 45% and unacceptable in 55% of the cases. Breed was the only factor that could be correlated with the outcome. The procedure failed in 86.5% of the cocker spaniels. When surgical outcomes in breeds other than cocker spaniels were evaluated, 63% were acceptable and 37% were unacceptable. Sharpeis were found to have an ear canal of small diameter compared with that of other breeds and a tendency to have better outcomes.