OTOTOXICITY ASSESSMENT OF A CHLORHEXIDINE OTIC PREPARATION IN DOGS

Isolated reports have alluded to the potential ototoxicity of the anti septic flushing agent chlorhexidine. To determine the effect of chlorh exidine acetate (0.2%) upon vestibular and cochlear function, this sol ution was placed twice daily for 21 days in the external ear canals of dogs with intact tympanic membranes and dogs with myringotomies (surg ically ruptured tympanic membranes). Vestibular function was assessed by daily neurologic examination, while auditory function was assessed by recording brainstem auditory evoked potentials (BAEP) at twice-week ly or daily intervals. Peak I of the BAEP represents cochlear activati on and is reduced or eliminated with cochlear damage. None of the dogs in either group in the study developed signs of vestibular damage. No significant changes (P less-than-or-equal-to 0.05) in the latency or amplitude of peak I of the BAEP were seen; therefore, the use of 0.2% chlorhexidine acetate appears to be safe when instilled into the exter nal ear canals of normal dogs for a period of 3 weeks. Further, we obs erved no signs of ototoxicity in dogs with surgically perforated tympa nic membranes.