The use of a mirror reduces isolation stress in horses being transported by trailer

Abstract

Horse trailers are a common form of transportation for horses and ponies and often require the animal to travel alone or with a single companion. The current study investigated the effect of transporting horses alone, in company or with an acrylic safety mirror (measuring 81 cm × 61.5 cm) that provided surrogate companionship. The behavioural and physiological responses of 12 mature horses during a 30-min journey by trailer under the three treatments were compared. Behaviours (vocalisation, eating, head-tossing, pawing, and head-turning) were recorded. In order to assess circulatory changes that occur as part of the response to transport, heart rate (HR), rectal ( T r) and ear-pinna ( T p) temperatures were recorded. When travelling with a live companion significantly less time was spent vocalising ( p < 0.001), head-turning ( p < 0.001), head-tossing ( p < 0.01) and pawing ( p < 0.01); eating behaviour increased ( p < 0.05). Physiological responses (increases in HR and T r and decreases in T p) were also significantly reduced when travelling with a live companion ( p < 0.01). Travelling with the mirror did not significantly affect physiological responses compared with travelling alone, but the rise in T r and fall in T p was reduced ( p = 0.052 and p = 0.051, respectively) and can be considered a trend. When travelling with a mirror significantly less time was spent turning the head ( p < 0.01), vocalising ( p < 0.05) and head-tossing ( p < 0.05); eating behaviour increased ( p < 0.05). The only significant difference between travelling with a live companion and a mirror was that the time spent turning the head round was less with a live companion ( p < 0.05). The provision of surrogate companionship in the form of a mirror was found to be preferable to travel alone, but where possible a live companion is recommended. Isolation during transportation was found to suppress feeding behaviour. Although peripheral blood flow ( T p) has been used to assess transport stress in other species it has not previously been used in the horse. Further evaluation of this non-invasive measure is now required.