Horses throughout the ages have been transported for a variety of reasons including breeding, military endeavours, competitions, ceremonial proceedings, pleasure activities, biomedical purposes, and slaughter. Transformation of the modes in transporting horses has progressed from the utilisation of boats or ships to move cavalry horses, to conveying racehorses in vehicles drawn by other horses in the early 1800’s, followed by railways until the 1920’s. Motorised conveyances were developed in the middle 1900’s and trailers or vans hauling pleasure, show, and racehorses became essential in the horse industry. The 1960’s to 1970’s were known as the “trailer age”, since it was commonplace for powerful cars to pull horse trailers (Leadon, 1999). The veterinary literature of this era also documents an increase in accidents, ailments, and other related stress incurred while transporting horses (Stull, 1997). Today, airlines expediently fly horses around the world.
The size of the horse transportation industry is seldom appreciated by those not associated with it. Recreational horses include a diversity of individuals that vary greatly in the frequency, distance, and method of their movement. Although Government statistics and breed societies do not document the use of trailer transportation for holiday and leisure activity, on the basis of figures compiled by and extrapolated from the Irish Thoroughbred Breeders Association in 1994, 605,900 Thoroughbred horses could have been transported for either racing or breeding in 37 of the major racing countries in 1990 (Leadon, 1999).
National and international trade and competitions involving athletic horses are becoming more frequent, the Fédération Equestre Internationale (FEI) organises more than 250 events in Europe each year in the elite sector of the equestrian disciplines, and there is a need to limit potential sources of stress during transportation of horses used in sport to ensure adequate performances as well as to prevent poor welfare (Leadon, 1999; Broom et al., 2002). Although the precise number of horses regularly transported throughout the U K is not known, if even 50% of the 900,000 privately owned horses in the U K travel just once per month and the 65,000 professionally owned horses in the U K travel once per fortnight this would equate to 2.23 million journeys per annum (Anon, 2005).
The effects of transportation on the health of the individual are not only a cause for concern to those concerned with welfare (Leadon, 1994) but can also adversely affect the horse’s behaviour and performance, even in horses that appear to adapt superficially to transport (Cregier, 1987). Previous equine transport studies such as Smith et al. (1994a,b) and Waran et al. (1996) have examined the behavioural and autonomic responses of orientation during travel. Neuroendocrine responses (Baucus et al., 1990), immunological changes (Stull and Rodiek, 2000), and water deprivation during transportation of horses (Friend et al., 1998) have also been extensively studied.
Optimising conditions experienced during transportation is therefore important in order to minimise levels of stress, and the detrimental physiological effects which may consequently occur. Although many efforts have been made towards improving horse transportation through husbandry, care, training, and trailer design, there have been no controlled studies examining the effects of surrogate companionship to assist in minimising the negative physiological and/or behavioural effects of stress during travel.