Horses transported in trailers can certainly experience a range of environmental temperatures and relative humidity, and exposure to different allergens and different contaminants.  Horses being moved must adapt to different management strategies, possibly exposure to new horses and unfamiliar spaces, unfamiliar movements beneath their feet, and different water and feeding patterns.  So if you haul horses, all of these parameters must be considered.

One thing you can do is drive slower, take turns slower, and avoid stopping or starting quickly as all of these movements increase stress on the horse’s legs.  Although some people prefer to tie horses when hauling, it has been shown horses are less stressed when not tied.  When tied, the horse cannot always adopt the safest and most comfortable posture while the vehicle is in motion.  Also, tying the horse’s head prevents normal drainage of the respiratory tract and has been shown to predispose horses to pneumonia, so if you do tie horse’s heads, you should not haul them for over one hour without untying them to allow then to put their heads down for drainage purposes. 

Hauling can also be difficult on horses due to disruption of their eating, drinking, and resting schedule. Even if you stop for breaks, many horses will not drink enough water to maintain hydration, which decreases gut function and can lead to colic.  Also, horses cannot eat on schedule when being hauled in many cases, and this can lead to colic. 

Hauling horses can be stressful on everyone if the horse is not properly trained to load and unload. Many horses are injured during loading accidents and part of this is because traditional loading training involves negative reinforcement.  The veterinarians at the Royal Veterinary College in Britain indicate that the most important aspect of a pressure-based training system is not the application of pressure but the release of pressure.  Also, the use of positive rewards for positive responses may increase the speed of response. 

It is important to train the horse to stand still at every point on the wrap when loading and unloading, which will help prevent less rushing to get on or off the trailer and subsequent accidents.  All horses should be trained to load and unload when they are as young as possible. Reducing the height of the step up by using a ramp will help, as does making the ramp feel as solid as possible. 

Transporting a horse interrupts a horse’s regular drinking, eating, urinating and resting.  Also, trailoring requires significant energy expenditure to continually maintain their posture in a moving trailer and because of this, it is important that a rest period be allowed after transport. 

Another concern is hauling horses immediately after competition as they are already tired and without adequate rest, the trip can be stressful and fatiguing for the horse.  As traveling is a stress, always make sure your horses are currently vaccinated at least 2 weeks before transporting. 

In order to remain upright, horses make postural adjustments that allow them to compensate for the changing motion of the vehicle.  Horses adopt a bracing posture while the vehicle is moving in which the hind legs and forelegs are wide apart.  The forelimbs are advanced forward and the head and neck are raised, placing more weight on the hind quarters.  If horses are packed too tightly in the trailer and do not have enough room to adopt this posture, they can lose their balance and injuries can occur.  It is important to realize that to maintain this posture, horses must expend a considerable amount of energy when riding in a trailer so it is not like they are just standing back there riding along all relaxed.  We know the horse is working to stand steady because of the increased heart rate noted in horses when the trailer is moving. 

Another study looked at position in the trailer. Horses facing the rear of the trailer expended lower energy and heart rates compared to horses facing forward or facing sideways to the direction of travel.  Also, horses facing toward the rear showed fewer losses of balance, carried their heads and necks lower and showed a less rigid posture. Because of this, you may want to consider hauling your horses backward and see if they have more energy for competition after the ride versus hauling them forward or angled forward.  Also, if you have to haul a horse with an injured leg, the injured leg should be toward the rear of the trailer to protect it from the effects of stopping the vehicle.