Brainstem auditory evoked potential findings in a French bulldog with bilaterally congenital sensorineural deafness

A 3-month-old, intact male French bulldog was suspected of deafness. The dog was irresponsive toenvironmental noises generated out of sight, but normal responses were noted for visual stimuli. No abnormalitieswere observed on the neurological, otoscopic, radiographic, and blood examinations. To diagnose the apparent deafness,brainstem auditory evoked potential (BAEP) was recorded in the presented dog together with a normal dog. Whilethe BAEP from the control dog showed a normal wave consisting of 5 peaks, absence of all peaks was noted inthe suspected deaf dog. Therefore the dog was definitively diagnosed as bilaterally congenital sensorineural deafness.Keywords : brainstem auditory evoked potential, congenital sensorineural deafness, French bulldog In recent decades, the occurrence of congenital deafnesshas been increased in dogs relative to the increased aware-ness among breeders, owners and clinicians [13]. Generally,auditory function is necessary for avoiding traffic accidentand other danger incidence. Because deaf dogs are easily sur-prised and have an increased tendency to bite, they are hardlysuitable for use as working. Therefore the puppy with bilat-eral deafness needs to be trained by a responsible owner, butthis kind of training is difficult and unfamiliar. By these rea-sons, bilaterally deaf puppies are easily euthanized [7].If the proper diagnosis of hearing impairment could bedone in dogs, especially working breeds, it will decrease costand efforts for being needed in training. Bilateral deafnesscould be evaluated by monitoring behavioral responses forsound stimuli presented outside of the visual field or with theanimal blindfolded, taking care to avoid visual or vibratorycues [11]. However, behavioral testing is often unreliable andsubjective [1]. Therefore several objective methods, includ-ing electroaudiomerty-encephalographic, audiometry, respira-tory audiometry, tympanometry, auditory evoked responses,and acoustic reflexes, have been used for diagnosing audio-logical or otological disorders in veterinary medicine [10].Among those methods, the brainstem auditory evoked poten-tial (BAEP) has been proven to be the most objective andnon-invasive assessment of auditory function [14, 15]. There-fore the BAEP is frequently used as a screening test for deaf-ness. Previously congenital deafness had been recognized inFrench bulldog, but the BAEP finding has not been reportedin this breed [11, 13]. Therefore this report firstly describesthe clinical and diagnostic features of bilaterally congenitalsensorineural deafness (CSD) in a French bulldog using theBAEP.A 3-month-old, intact male French bulldog was presentedwith suspected deafness. This dog was the youngest onefrom 4 literamates, and the other 3 littermates had no hear-ing disabilities or other diseases. The owner had not observedany response of the dog for sound stimuli since 1 month agoadoption. There was no history of exposure to any causes ofdeafness; illness, head trauma or ototoxic drugs. Physicalexamination revealed mild erythema on the bilateral earpinna and epidermal collarettes on the abdomen. Its coatcolor was predominantly white and black, especially whiteareas presented on the ventral thorax, abdomen, feet, foreleg,and head. On behavior testing, the dog was irresponsive toenvironmental noises generated out of sight, but normalresponses were noted for visual stimuli. Any startle responseswere not elicited to sudden loud noises. Bilaterally, intacttympanic membranes and the grossly normal external earcanals were observed on the otoscopic examination. Thetympanic bulla was examined by radiography with differentviews of the open mouth dorsolateral, lateral-oblique, androstrocaudal projections. Those radiographic studies revealednormal bone density and no fluid density or diminution offoraminal detail within the tympanic bulla. In addition