As you haul your horse, he must constantly adjust his body weight to keep his balance, working his muscles hard. He may even have to scramble to stay on his feet.

Here, I’ll explain how your horse balances in your moving trailer. Then I’ll give you eight ways to help keep him safe, secure, and on his feet. Finally, I’ll provide pros and cons of four common trailer designs, in terms of how they affect equine balance.

Balancing Act

Since your horse’s body weight is so high above his feet, he has to work hard to keep his weight stable when your trailer is randomly swaying, bumping, and moving down the road. He knows what to do to stay upright; his every instinct drives him to stand up and protect himself from falling over or down.

How does your horse balance? My colleague, Chris Riley, PhD — a professor of equine clinical studies at Massey University at the University of New Zealand — recently trained six GoPro video cameras on horses as they traveled in two-horse, forward-facing trailers.

Dr. Riley’s documentation confirmed that when horses try to balance in a trailer, they spread their legs forward, backward, and to the side in a base-wide stance to help them increase the surface area of their weight in contact with the trailer floor.

This is basically the same thing you’d do if I tried to push you over while you were standing up, especially if I tied your hands behind your back. Horses are horizontal animals, while we’re vertical animals, so our methods of aligning our spines might be different, but our concepts of gravity, momentum, and inertia are similar.

What You Can Do

Here are eight things you can do to help your horse balance inside the trailer as you go down the road.

• Drive carefully. Scramble marks in trailers attest to the efforts of horses to balance themselves and often point to poor driving skills. Good driving skills are crucial to helping your horse keep his balance. Turn and accelerate slowly, and brake gently. More than 65 percent of your horse’s body weight is on his forequarters, so when you apply the brakes, it’s difficult for him to keep his hind legs on the floor. He’ll tend to tip forward, bracing with his front legs. When you brake hard, his hind legs will creep forward, under his body.

• Invest in the right size trailer. To balance correctly in your trailer, your horse must have free use of his head and neck. If your trailer is too short for him to be able to raise his head, he’ll lack the ability to engage this critical balancing maneuver.

• Invest in a quality trailer. Quality structural materials in your trailer’s walls, bulkheads, and flooring will provide balancing support for your traveling horse.

• Invest in quality, cushioned fittings. Invest in heavy-duty, cushioned fittings anyplace your horse will touch to lean and balance, including chest bars, butt bars, stall sides, and dividers. Note that in a forward-facing, two-horse trailer, he’ll consistently use the chest bar for balance during braking. In a slant load, he’ll lean against the side dividers or his travel buddies.

• Invest in stall mats. High-quality mats absorb shock and encourage grip.

• Keep your trailer clean. Keep your trailer floor free of urine and manure, which can cause slick conditions.

• Consider bedding. Bedding materials can provide traction, but can also cause respiratory problems if inhaled. Look for large, dust-free shavings. Mix in liquid absorbing pellets to control urine. I’ve used a small amount of damp sand or dirt in trailers without good mats or sufficient bedding.

• Tie him correctly. If you tie your horse in the trailer, leave enough slack so that he can balance by moving his head and neck, but not so loose that he can catch a leg in the tie rope.

Trailer-Design Pros & Cons

Your trailer’s design can help or hinder your horse’s balance. Here are the pros and cons of four common trailer designs.

1. Front-facing trailer with dividers.

Pros: Your horse can use the butt and chest bars to balance himself during acceleration and braking.

Cons: This trailer design might not offer enough space for long, tall horses to travel comfortably and stay balanced, although you can look for one built to accommodate larger horses. Make sure the trailer is wide enough for your horse to spread himself laterally to keep his balance around curves. This trailer’s full dividers can impede your horse’s balancing maneuvers.

2. Slant-load trailer with dividers.

Pros: This trailer design places the horse’s body slightly uphill toward the crown of the road. Horses seem to like this orientation, as they can see each other easily and tend to stay calm. This design also tends to accommodate larger horses, offering more space than in other trailer types.

Cons: Some studies point to unnatural weight-loading of a horse’s legs when standing in this position for long periods and a horse’s inability to use two legs to counter the force of braking. During hard braking, he can even slide under the divider (or other horses). More research is needed; I’ve never had an issue with this in many thousands of miles of traveling with a slant-load trailer across the country.

3. Rear-facing two-horse trailer with divider.

Pros: Horses can use the butt bar or bulkhead (depending on trailer design) and chest bar (if present) to balance for acceleration, turning, and braking. Videos show that this design allows horses to balance by sitting down as well as pushing against the bulkhead, which works well in hard-braking situations.

Cons: We see incidents of horses going over the ties or bars during acceleration in this trailer type. It’s unknown whether this is due to trailer design or if horses don’t prefer this orientation. However, many horses choose to face rearward in an open stock trailer, so more research is needed.

4. Open stock trailer.

Pros: Loose horses can choose their own orientation, based on environmental and physical factors. Even when tied, they can still choose a more comfortable orientation than they can when forced into a particular orientation in other trailer types, because there’s more room. Bracing and balancing is also easier.

Cons: There’s nothing for horses to brace themselves on except the trailer sides or bulkhead. Horses have so much room that if they’re thrown forward under hard braking, they often end up down — or even crush each other if multiple horses are in a compartment.

Rebecca Gimenez, PhD (animal physiology), is president of and a primary instructor for Technical Large Animal Emergency Rescue (www.tlaer.org). A Major in the United States Army Reserve, she’s a decorated Iraq War veteran and a past Logistics Officer for the American Veterinary Medical Association’s Veterinary Medical Assistance Team, which serves as first responders to ensure high-quality care of animals during disasters and emergencies. She’s an invited lecturer on animal-rescue topics around the world and is a noted equine journalist.