Effects of loading and transport on the heart rate and behaviour of horses

Abstract

Although there is much anecdotal evidence to suggest that some horses are stressed during transport, very few empirical studies have been done that describe and quantify the responses of horses to transport. The aim of this preliminary study was to describe the behaviour and heart rates of horses during loading and transport that would enable further studies to be carried out on the effects of different journey lengths and management procedures. Therefore, the behaviour and heart rates of horses were measured during loading, confinement in a stationary vehicle and transport for 25 min. In the first study the behaviour and heart rates of 32 horses of various ages ranging from yearlings to over 3 years, were compared during loading. Evasive behaviour during loading was only observed in very young horses, and the time the yearlings took to load (368 s) was much greater ( P < 0.05) than that of 2-year-olds (29.5 s), 3-year-olds (21.5 s) and those over 3 years of age (5 s); however, although mean heart rates during loading were elevated in all groups they did not differ significantly between age groups. In the second study, the behaviour and heart rates of seven horses were compared in either a stationary or a moving vehicle. Horses were tested with a companion horse to remove any influence of isolation, and hay was available. During transit the horses adopted certain body postures (e.g. forelegs forward and apart and hindlegs apart) that were thought to be due to their need to brace themselves in order to maintain balance. They also spent less time feeding (27% of scans in transit vs. 72% in the stationary vehicle; P < 0.05). Heart rates were on average 18 beats min −1 higher ( P < 0.001) in the transported compared with the stationary situation. The results suggest that although loading is particularly disturbing for naive horses, it is also stimulating in some way for more experienced horses. It was concluded that the elevated heart rates and abnormal body postures that were recorded during 25 min of transport indicated that transport is at least physically stressful for horses and may cause weight loss and fatigue in horses on longer journeys.