Equine Behavioural and Physiological Responses to Auditory Stimuli in the Presence and Absence of Noise-Damping Ear Covers.

Despite numerous studies investigating responses to visual perception, there is limited research into how horses respond to different auditory stimuli. Although 'noise-damping' ear covers are frequently used on sport horses to minimise distraction from external auditory stimuli, the effectiveness of ear covers has not been established. This study aimed to (i) investigate the responses of horses to different sounds commonly present in a competition environment, and (ii) compare these responses in the presence and absence of ear covers. A total of 18 horses were presented with 5 sounds commonly heard in competition or stable environments both with and without ear covers, in a randomised order crossover design. Behavioural and heart rate responses were recorded. Responses were compared between sounds and with/without ear covers. Differences in physiological and behavioural responses to different complex auditory stimuli were shown. An overall difference in physiological and behavioural responses with and without ear covers was detected, although the only difference in heart rate between ear covers and no ear covers that individually achieved significance was the feed sound. These findings suggest that horses can discriminate sounds and alter their responses based on the individual stimulus, and these responses are reduced when wearing ear covers with varying effectiveness for different sounds.