An inconsistent social buffering effect from a static visual substitute in horses (Equus caballus): A pilot study

Social buffering occurs when a companion helps to reduce a subject’s stress response during a stressful event and/or to recover more quickly from a stressful event. The aim of this study was to determine if any social buffering function of a horse companion can occur in relation to a visual substitute (poster of a relaxed horse face) during two different stressful situations: a novel object test (a ball presented gradually) and an umbrella test (sudden opening of an umbrella). In order to evaluate the effect of a horse face poster on the subject’s stress responses, behavioral (reactivity score) and physiological (heart rate) measurements were taken. Each of the 28 study subjects completed four trials: two novel object tests and two umbrella tests—each with a relaxed horse face poster and a pixelated poster (control). Our results showed that the presence of a horse face poster might significantly reduce the behavioral response (reactivity) of subject horses in the novel object test but did not improve heart rate recovery (HRR) time. The horse face poster did not have a significant effect on the behavioral reaction or HRR in the umbrella test. Any effect of a horse face poster as a potential social buffer might potentially depend on the nature of the stressful event