This study explores how different levels of rein tension affect the stress response and heart activity in horses, focusing on the differences between younger and older horses. We aimed to understand whether the experience of older horses makes them less sensitive to rein tension compared to younger ones. Using heart rate variability (HRV) as a measure, we found that higher rein tension activated the horses’ stress response but did not overwhelm them, suggesting the tension used was within a safe range. Interestingly, older horses handled the tension better, likely due to their training experience. We also discovered that using different types of equipment, such as a bit or halter, affected how the horses responded, with the bit causing higher stress levels. Our findings suggest that while rein tension can trigger a mild stress response, it may also be part of the learning process for horses, helping them adapt. This research could inform future training methods that take into account the horses’ stress responses, potentially improving their welfare by identifying optimal training conditions.

Read the full article in the Journal of Animal Science.