It is dangerous for both riders and horses when a horse suddenly startles. Sometimes horses do this in familiar environments because familiar objects may look different when rotated. The purpose of this study was to determine whether horses that had been habituated to a complex object (children’s playset) would react to the object as novel when rotated 90 degrees. Twenty young horses were led past the playset 15 times by a handler. Next, the rotated group was led past the rotated playset 15 times. Each time the horse was led by the object was a pass. The behavioral responses observed and analyzed were ears focused on the object, nostril flares, neck raising, snort, avoid by stopping, avoid by moving feet sideways, and avoid by flight. An increasing reactivity scale was used to quantify behavioral responses. A two-sample t-test was performed on the reactivity scores comparing the first pass by the novel object to the first pass by the rotated object. The horses in the rotated group reacted to the rotated orientation similarly to the first exposure (p = 0.001, α < 0.05). Being aware of potential reactions to changes in previously familiar environments can help keep the handler safer.

It is dangerous for both riders and horses when the horse suddenly startles. Sometimes horses do this in a familiar environment, with a possible cause being that familiar objects may look different when they are rotated. The purpose of this study was to determine if a horse that had been habituated to a large object (children’s plastic playset) would perceive the object as novel when the object was rotated 90 degrees. Twenty-four young horses were habituated to one side of the playset and led 15 times by a handler until they showed no behavioral reactions. The behavioral signs observed and analyzed were ears focused on the object, nostril flares, neck raising, obvious exhale, avoid by leaning away, and avoid by moving side. The most common reactions observed were ears focused on the object, nostril flares and neck raising. Reactions were mild, because the horses used were safe to lead and all procedures were done at a walk. When the playset was rotated, the behavioral signs observed were similar to behaviors shown on the first exposure to the playset. An unpaired two-sample Wilcoxon test was performed on the behavioral signs, comparing the number of behavioral signs present on pass 1 compared to pass 16 (rotated). There was a significant difference between the control and rotated group (W = 9.5, P = 0.001572, P &lt; 0.05). Horses previously habituated to a large object perceived the rotated object as novel. Horse safety can possibly be improved by habituating a horse to all sides of a novel object.