Effect of total ablation of the external acoustic meatus and bulla osteotomy on auditory function in dogs.

Seven dogs with end-stage bilateral otitis externa were evaluated for auditory function before and after bilateral total ear canal ablation and lateral bulla osteotomy. Evaluations were performed by owner questionnaire and by recording brainstem auditory-evoked responses. Prior to surgery, all dogs could hear a loud voice or noise, however, only 3 dogs responded to a voice spoken at a normal level. Of the 14 ears tested electrodiagnostically, only 1 did not have a response, using air-conducted or bone-conducted stimuli. After surgery, 2 dogs responded to a normal voice, but all 7 responded to loud voices or noise. Three ears that had recordable brainstem auditory-evoked responses to air-conducted stimulation prior to surgery, failed to respond after surgery. Ears that responded to bone-conducted stimulation prior to surgery also responded after surgery.