Brainstem auditory-evoked response in dogs

V eterinarians, researchers, breeders, and owners all have an interest in the accurate assessment of hearing in dogs. In a study 2 of > 1,000 Dalmatians, 21.6% of the dogs had severe unilateral deafness and 8.1% had severe bilateral deafness. This finding prompted the British Dalmatian Club of Great Britain to recommend auditory assessment for all Dalmatian puppies and breeding stock. 1 Dogs of working breeds also require good hearing and rely on both ears to localize the source of sound. Diagnosis of hearing impairment in these dogs saves time and prevents money from being wasted in expensive training programs. ] These factors make the use of behavioral responses a poor choice for inexperienced testers, young puppies, and clinical patients. any veterinarians and researchers have turned to electrodiagnostic testing as an alternative to behavioral testing in assessing auditory function in dogs. The brainstem auditory-evoked response (BAER) is one of the most frequently used testing modalities in this respect because the test is objective, reasonably easy to perform, noninvasive, safe, and cost-effective, compared with other objective measures of auditory function. The testing apparatus is portable, and test time is brief. Results are reliable, sensitive, anatomically specific, generally independent of the level of consciousness, and resistant to the influence of drugs and yield a comprehensive index of neurologic status. his article reviews current knowledge regarding the use of BAER in dogs, including basic principles of technique; effects of nonpathologic subject factors, stimulus factors, and recording factors on the BAER; and common applications of the BAER in dogs. The term BAER will be used in preference to the auditory brainstem response, the brainstem auditory-evoked potential, the brainstem evoked response, and the brainstem evoked potential. atures of the BAER When repetitive sensory stimuli are received, the brain responds with consistent changes in electrical activity. These changes are collectively referred to as evoked responses or evoked potentials. As one of a large family of evoked responses, the BAER represents the mean value of recordings of activity in cranial nerve (CN) VIII and the auditory portion of the brainstem in response to externally applied acoustic stimuli.