Pack along a few vital items just in case you trip doesn’t go as planned.

The drive home from the show was supposed to be short—only 20 minutes with your trailer in tow. But an accident has shut down the highway. A line of cars stretches as far as the eye can see, ahead and behind you. You and your horse won’t be going anywhere soon.

Situations like this are the reason it’s wise to “over-prepare” for any trailer trip, no matter how short or routine. A horse stuck in a trailer on a summer day can become severely dehydrated, so make it a habit to always carry water and a bucket in your trailer. Large water jugs—available from recreational vehicle suppliers—are perfect for this task, but you can also use an empty, lidded supplement tub, provided you’ve cleaned it thoroughly. With this extra water on hand, you can step into the front of the trailer and offer your horse a drink when traffic is stopped. While you’re back there, make sure all windows and vents are open to maximize airflow in the space—you can leave the upper back doors of a two-horse trailer closed for safety if the space is otherwise ventilated.

Having extra supplies in your trailer can save the day in case of emergency.

A horse standing in a stopped trailer can become fretful. Pack an extra half-bale or so of hay for any road trip so you can keep your horse’s hay net filled—and keep him occupied—if you’re stuck in traffic. If a full hay net isn’t enough to stop your horse from kicking or scrambling, see if you have sufficient room to creep forward slightly with the truck and trailer. Even a little movement will remind a horse to keep his feet underneath him for balance.

Click here to learn what three things to investigate when your horse is uneasy in the trailer.

Finally, never unload a horse in a traffic jam, even in the worst backup. Doing so will put your horse, yourself and the motorists around you at significant risk of injury. And, of course, a catastrophe could occur if a horse gets loose on the highway. Keep him in the trailer, no matter how fretful he becomes.