The effect of ocular blinkers on the horses’ reactions to four different visual and audible stimuli: results of a crossover trial.

The research article discusses a study investigating the impact of ocular blinkers on how horses respond to different visual and audible stimuli. It was found that horses wearing blinkers exhibited a higher heart rate when exposed to unfamiliar sounds and a lower heart rate when dealing with familiar, primarily visual stimuli.

Explanatory Summary

The researchers carried out a balanced crossover trial, a common type of clinical study where participants receive different treatments over various time periods, to examine the impact of blinkers on horses’ response to various sensory stimuli.

• Eight driving horses from various breeds were randomly assigned to wear blinkers (a device limiting the horse’s peripheral vision) or not to wear blinkers during the initial phase of the trial. These horses were subjected to four distinct types of stimuli – the rattling of chains, the sound of a cap gun, the sudden opening of an umbrella, and the shaking of an aluminum can containing coins.
• Two weeks later, the process was repeated with the order of wearing blinkers reversed. The horses’ reactions were recorded quantitatively as inter-beat times (time between heart beats) and qualitatively through video recordings.
• The results indicated that the presence of blinkers significantly decreased the inter-beat times (interpreted as an increase in heart rate) when the horses were exposed to a new, unfamiliar sound. On the other hand, the use of blinkers significantly increased the inter-beat times (interpreted as a decrease in heart rate) when the horses were exposed to primarily visual, familiar stimuli.

Implications and Conclusion

• The study suggests that trained driving horses wearing blinkers show an increase in heart rate when exposed to a new sound, indicating a potential increase in anxiety or distress. However, for familiar, mainly visual stimuli, the presence of blinkers led to a decrease in heart rate, signalling a potential calming effect.
• The findings can be particularly relevant for equine practitioners and horse trainers in adjusting their training methods based on the nature and type of the stimuli that horses regularly encounter. Furthermore, the findings may hold importance for horses with limited vision due to trauma or disease, where blinkers might be used as a means to manage their reactions to environmental stimuli.