Use of a hearing loss grading system and an owner-based hearing questionnaire to assess hearing loss in pet dogs with chronic otitis externa or otitis media.

BACKGROUND: Hearing loss is important when assessing the suitability of dogs with otitis externa/media for medical or surgical therapy. HYPOTHESIS/
OBJECTIVES: To assess an owner-completed questionnaire as an indicator of hearing loss and a canine hearing loss scoring system in chronic canine otitis. ANIMALS: One hundred hospital population dogs referred for chronic otitis investigation.
METHODS: Owners completed a questionnaire to assess their dog's response to common household noises. The presence of otitis externa or media was determined and brainstem auditory-evoked response measurements were performed on each dog. The minimal hearing threshold (MHT) in decibels normal hearing level (dB NHL) was recorded and categorized according to the human World Health Organization grading system into five grades from 0 to 4 with cut-off values of ≤25 dB NHL, 26-40 dB NHL, 41-60 dB NHL, 60-80 dB NHL and ≥81 dB NHL.
RESULTS: The questionnaire correctly determined normal hearing in grade 0 cases, but did not reliably detect unilateral or grade 1 bilateral hearing loss. For dogs with bilateral hearing loss ≥ grade 2, questionnaire sensitivity was 83% [24 of 29, 95% confidence interval, (CI) 64-94%] and specificity was 94% (67 of 71, 95% CI 86-98%). Higher grades of hearing loss were significantly associated with the presence of otitis media (P < 0.01). CONCLUSIONS AND CLINICAL IMPORTANCE: The questionnaire may be a useful in-practice screening tool in chronic canine otitis for moderate to severe bilateral hearing deficits (MHT ≥41 dB NHL). The hearing loss grading system may help clinicians make therapeutic decisions. Chronic otitis media may be associated with higher grades of hearing loss.