When loading a horse in a trailer, it is important to recognize and carry out safe loading practices. It is your job to make the loading experience pleasant for the horse and safe for the handler.
Before loading, make sure the horse is wearing a halter that fits properly and will not slip off or break during the loading process.
Always lead your horse onto the trailer using a lead rope rather than leading it by the halter. By using a lead rope, the handler will have more control of the horse if it shies or backs away from the trailer. It is also important that the handler not wrap the lead rope tightly around his or her hands. Instead, the handler should lead the horse with the lead rope held in the left hand in a loose coil and in the right hand near the halter.
Before approaching the trailer to load the horse, remove any obstacles that might scare or prevent it from loading. Make sure the trailer partitions are securely fastened so they don't swing in the horse's way during loading. Open all vents and windows needed, hang any hay nets, and spread shavings or straw prior to loading.
It is also important to park the trailer in a safe location, away from any obstacles that might injure a horse if it runs back, refusing to load. You should also make sure you have first loaded all other supplies, tack, health papers, etc.
Once the trailer is prepared and these safety precautions taken, you may load your horse.
Ideally, you will tie your horse in the trailer using a quick release snap tie. These trailer ties are long enough to allow the horse to move its head and be comfortable but short enough to prevent it from getting its head under or over any partitions. If you do not have a quick release snap, then tieing your horse with a lead strap and a quick release knot will help serve the same function in case of emergency.
Once the horse is loaded and properly tied, secure all partitions, including the butt bar that may be located behind the horse in the last section of the trailer. If the back door of the trailer were to open during travel, the butt bar would be the only thing to help prevent the horse from backing off the moving trailer. The butt bar also helps prevent horses from prematurely backing off the trailer when the trailer door is opened prior to unloading.
Once horses are loaded, it is best to get on the road. Some horses may become anxious and will quickly get hot in an immobile trailer.
From eXtension HorseQuest