Objective Assessment of a Hearing Protection Device for Canines.

Noise-induced hearing loss (NIHL) has been reported in both people and canines and can raise the hearing threshold. In people, hearing protection devices (HPD's) are utilized to reduce the risk of hearing loss. In canines, HPD's have been developed, but none, to our knowledge, have been objectively tested to determine their ability to reduce incoming sound. We hypothesize that a canine hearing protection device (CHPD) will effectively protect hearing in canines by increasing hearing thresholds. Twenty-one apparently healthy canines between the ages of 4-69 months were anesthetized for routine surgical sterilization. Hearing thresholds were established using over-the-ear headphones (OTEH); starting at 70 dB nHL, sound was gradually diminished by 10 dB nHL until wave V was inapparent as recorded by BAER. Hearing thresholds were then established in the same patients while wearing CHPD. Median hearing thresholds for canines without the CHPD were 40 dB (range 5-70 dB) in the left ear and 50 dB (range 20-70 dB) in the right ear. Median hearing thresholds for canines with the CHPD were >70 dB AU (range 65-70 dB). Twenty out of twenty-one canines had hearing thresholds > 70 dB with the CHPD in place. The CHPD objectively increased the hearing threshold in canines, blocking sound of less than or equal to 70 dB nHL. This device could be utilized to lessen the likelihood of NIHL in canines.