The effect of chronic otitis externa-media on Brainstem Auditory Evoked Potentials in dogs

Abstract

The objective of the study was to present normative Brainstem Auditory Evoked potentials (BAEP) data elicited by both air-conducted clicks (30-100 dBHL) and bone-conducted clicks (100-130 dBHL) for healthy dogs, and dogs with chronic otitis externa-media (COEM). The data were analyzed to acquire reference values in 55 normal dogs and to estimate the degree of hearing impairment associated with the disease. Fifty-four dogs with COEM were divided into two degrees of severity. The first one included dogs with severe (n = 16), and the second with moderate COEM (n = 38). The recognisability wave V was found higher than the others at every stimulation level. Wave VII was not seen by the bone-conducted click at all stimulation levels, and also in cases with severe COEM by the air-conducted click. Recognisability of wave V was seen more than 50% at 60 dBHL in severe COEM. This ratio was seen at 30 dBHL in moderate COEM. In healthy dogs, the latencies of waves (I-VII) were compared between the left and the right side, and there were no significant differences between each side except for a shorter latency of wave VI. In conclusion, COEM caused increasing latency rather than total deafness, and BAEP can be suggested as an ancillary diagnostic tool in ear disorders.