Use of BAER to identify loss of auditory function in older horses.

The research focuses on the use of Brainstem Auditory Evoked Response (BAER) to determine auditory issues in older horses, comparing the outcomes to those of younger horses. The study found that older horses experience significantly worse BAER readings, indicative of partial hearing loss.

Objective and methodology of the study

• The purpose of the research was to test the effectiveness of BAER (Brainstem Auditory Evoked Response) in identifying hearing loss in older horses. The authors hypothesized that older horses would exhibit worse auditory function than younger ones.
• The study involved measurement of BAER waveforms in response to click stimuli in a group of five younger horses (between 5 and 8 years old) and a group of four elder horses (between 17 and 22 years old).

Results of the study

• The findings revealed a significant difference in BAER thresholds and the amplitude of Wave V of the BAER between the two groups. The older horses demonstrated significantly worse BAER thresholds and lower BAER Wave V amplitudes to the 90-decibel stimuli above the normal hearing level. This deterioration reflected the partial hearing loss among the older horses.
• The term ‘BAER thresholds’ refers to the minimum sound level that can trigger a detectable electrical activity in the auditory pathway. A higher BAER threshold thus implies a poorer hearing capacity. Conversely, ‘BAER wave V amplitude’ denotes the strength of a specific part (the fifth) of the response waveform in the BAER. A lower amplitude of Wave V corresponds to lower auditory function.

Conclusions drawn from the study

• The researchers concluded that BAER assessment can effectively identify partial deafness among older horses. Consequently, these horses should be managed appropriately. Special care should be taken in noisy environments where hearing complications could expose the horse and possibly its owner to harm due to misunderstood or missed auditory cues.