The intensity with which a horse responds to separation from its group and subsequently to being alone is relevant for both horse and handler safety. Identification of training methods that might reduce responses to separation would be useful in practice.
The objective of this research, conducted at the Swedish University of Agricultural Science, was to investigate whether the initial presence of a familiar companion horse modifies responses to separation from the group, lowers stress levels (as measured by heart rate) and increases training efficiency. Researchers hypothesized that habituation to separation proceeds more quickly if the horse is first trained with a companion, and heart rate is lower when the horse is subsequently trained alone, compared to control horses trained individually from the start.
Young mares, kept in groups of four, were exposed to social separation: two horses of the group were trained singly and the remaining two horses were trained first with a companion, then alone. The training comprised of three steps whereby distance from the group was gradually increased. The final learning criterion was met when a horse fed calmly alone inside a test arena. Horses that were trained in a pair had to succeed in the final learning criterion (feeding calmly alone inside a test arena) together before they repeated the steps alone. Feeding behavior and heart rate were recorded.
There were no significant differences between singly trained mare and mares trained in pairs, indicating that the initial pair-training did not reduce stress responses in pair-trained horses. However, heart rate was significantly lower when horses were trained in pairs compared to when the same horses were subsequently trained alone.
It might not be efficient to habituate naïve young horses to social separation initially with a partner as these horses appear to have to relearn being in the test situation alone when switching to the individual training method.