Twelve mature horses (mares, n = 5; geldings, n = 7), age 8-22 years (mean 15 years) were used in this study. A wide range of size and breed of horse were among the twelve tested, none of whom travel regularly (eliminating the possibility of anticipating a journey to a competition etc.) and all of whom live permanently at grass together in a social group.
To transport the horses a Bahill Sportsman 2 horse trailer (extra height version) was used, towed by a Landrover Discovery. A removable Stable Mirror (mounted on MDF) measuring 81 x 61.5 cm was fitted inside the trailer for the experimental treatment, and an identical mirror mounted inside a stable to which the horses were exposed prior to the study. HR measurements were taken with a Polar Horse Trainer s610™ Heart Rate Monitor with electrode attachments fitted under an elastic surcingle. Tp was taken using a Raytec ® Laser Thermometer, and Tr with a NET-TEX Veterinary Digital Thermometer. Behaviour was recorded using a Samsung Digital Video Recorder, and the duration of behaviours was recorded during playback with a Nokia 6230 (stopwatch). All horses wore travel boots and a tail guard during travel.
This study measured dependent variables; behaviour, HR, Tp and Tr of twelve horses in response to three independent variables during a 30-minute journey by horse trailer; travelling alone, with a conspecific and with a travel-mirror. The order of treatment was counterbalanced to control for order effects (see table below).
Order of treatment
|HORSE||Treatment 1||Treatment 2||Treatment 3|
Although all twelve subjects had previous experience of being transported, none had travelled on more than two occasions in the twelve months prior to the study. Therefore, during the month prior to the start of the study, each horse was loaded and unloaded from the trailer to gain some familiarisation with the process, and ensure that there were no non-loaders among the group. The horses were then loaded a second time and left for two minutes on board the trailer with the ramp and doors closed, to check that none showed any aversion to confinement.
Also during this period, to ensure that there were no adverse reactions and that the horses were familiar with the sight of their reflection prior to the experiment, the horses were exposed to the mirror fixed inside the stable wall for two periods of at least 3 hours. Whilst in the stable, the horses were also familiarised with the travel boots and tail guard.
During the study, each horse was allowed at least 48 hours between each of the three treatments. The internal layout of the trailer and the companion horse (not included in the study) remained constant for each horse throughout the study, and hay was offered ad libitum during experimental sessions as is normal during travel. The journey was thirty minutes in duration, along minor roads that consisted of a number of bends and a slight incline but no hills.