LEARN to safely haul a trailer before you put a live animal into it. Drive in all weather conditions; ride in the trailer around your property to feel the stress it puts on your horse. TRAIN your horse to travel. Don't assume your horse knows HOW to ride comfortably in a moving cave.
BUY A TRAILER THAT IS SAFE for your horse. This means taking into account his comfort, as an uncomfortable horse can become agitated, causing the trailer to become unsafe. It should be long enough, tall enough, if it's a slant load it should be WIDE and TALL enough (a lot aren't: know how to measure it), has good ventilation and is light colored with cushioning on the floor to keep it cool. Road heat in the summer can fry a horse, both physically and emotionally.
GET THE RIGHT SIZED VEHICLE to do the job. Even if your truck is rated to tow the weight, a scrambling horse puts extra stress on the truck and can cause it to become unstable.
NEVER load a horse facing backwards unless the trailer is specifically designed for rear-facing travel. This puts excessive strain on the hitch.
NEVER hitch a "bumper pull" trailer to a bumper.
ALWAYS load a single horse on the left side or tie on the left side of slant loads, if at all possible. Most roads are "crowned" which means they are higher in the middle.
ALWAYS hitch so that your trailer travels level. If your horses are always standing uphill they may scramble or constantly shift position to compensate for the angle.
ALWAYS check your tires before you start out. Under inflated tires can cause sway.
ALWAYS check your trailer before you start out, stop down the road a mile or so to make sure everything's riding properly, and check after each stop.
NEVER allow your horse to stick his head out a window when you are in motion. If you are using a stock trailer, put a fly mask on your horse so bugs, hay and rocks don't hit him in the eyes (at 70 mph!)
ALWAYS be prepared. Carry first aid kits for your horse, your self, your vehicle and your trailer. Your kit should contain identification for you, your horse, and if your dog rides with you, him too. Your I.D. should detail who to contact in case of emergency and have pictures of not only the animal but YOU WITH your animal.
My publisher's website has free I.D. sheets to download Red Jeans Ink. USRider provided me with a "Limited Power of Attorney for Health Care" and "To Emergency Responders" so I added them to my book. Copy, fill out, keep one copy with your kit and one with your emergency contact.
Program your emergency numbers in your cell phone and designate them with the acronym ICE. Ex: ICE-Sally. This tells responders to call Sally In Case of Emergency.