Surgical placement and efficacy of a bone-anchored hearing aid in a dog with conductive deafness

The surgical placement of a bone-anchored hearing aid (BAHA), was investiga ted in a dog with chronic otitis. It had been treated by bilateral total ea r canal ablation and lateral bulla osteotomy (TECALBO). The dog was then fi tted with a bone-anchored hearing aid (BAHA). A titanium fixture was placed in the left parietal bone and allowed to osseointegrate for 126 days. Furt her surgery and tissue reduction allowed the fitting of a titanium abutment , and 21 days later the hearing aid was attached. Auditory function with an d without the hearing aid was tested by brainstem auditory evoked response (BAER) using a free-field alternating click stimulus (2-4kHz), at 16cm from the head. With the BAHA in place, BAER tests showed a hearing threshold of 30dB sound pressure level (SPL), while without the BAHA no BAER trace was reproducible even at 70dB SPL.