Many older trailers on the road today were built before important research was done on how to keep horses healthy and comfortable in transit. As you evaluate used trailers, consider these design features intended to meet horses' physical and physiological needs:
Ample room for a secure stance. A horse needs room to spread his feet to hold his balance in a moving trailer. Dividers that do not go all the way to the floor beside or in front of the horse allow more room for a wider stance.
Plenty of fresh air. The interior of a trailer is one of the dustiest environments a horse is likely to encounter, but proper airflow from front to back helps keep the dust moving out. Be sure your trailer has at least one vent opening in the nose and preferably along the sides as well as in the rear.
Room to lower his head. Even a properly ventilated trailer will contain some dust, so to keep his airways clear a horse needs to be able to drop his nose below his chest. Avoid older trailers that may have built-in mangers or tack storage areas located under the horses' noses.
A light interior. To a prey animal, there's not much that's quite as scary as being led into a dark cave. Features such as light colors, interior lights, ample windows and doors at the front all help horses see into trailers, so loading is easier and the occupants can be more relaxed in transit.
No protruding objects. Tie rings, window latches or other hardware that protrudes into the areas the horses occupy can cause injuries. Look for tie rings that lie flat when not in use.
Screens. Open windows and doors allow plenty of ventilation, but screens can keep out flying debris, such as litter, kicked-up gravel, bees and even lit cigarettes.
Breakaway features. Easy access in an emergency is crucial, and horses can get stuck in amazing positions. Look for emergency-release pins on dividers, bars and posts that can be operated quickly despite pressure from any direction. Welded-in center posts can become obstructions in an emergency, especially if the trailer overturns. Look for models without them or with removable ones.