You can avoid this illness with simple precautions taken both before and during transit.
Plan to Reduce Stress
The stress of transport can be immunosuppressive, or negatively affect the immune system, making the horse more likely to become ill during the hours in a trailer or van.
Mike Tomlinson, DVM, explains, “If you can eliminate as much stress as possible, have the animal in as good condition, and as used to shipping as possible, then the incidence of shipping fever is extremely low.”
Professor Emeritus Catherine Kohn, Ohio State University, says, “The longer the trip, the increased risk of shipping fever.” Like Tomlinson, she advises reducing biological stresses by supplying a safe environment—a stall where the horse breathes fresh air and stays calm and cool.
A comfortable trip starts with a smooth ride. “There is a huge difference between a semi-trailer and a two-horse bumper-pull—and a huge difference between a gooseneck and a bumper-pull,” says Tomlinson. “The gooseneck rides a lot smoother.”
Inside the trailer, keep the air clean and fresh through plenty of circulation. More airflow aids the horses’ breathing.
Tomlinson notes that a well-designed trailer has frequent air exchanges, through windows and vents. “I’ve learned that when in doubt, keep the windows open, but the window grilles closed.”
Your trailer should have roof vents for each stall, with controls to flow air forward or backward inside the trailer. In hot weather, move the lever air flows forward. In cold weather, switch the direction so air flows in reverse.
Horses seem to travel better when they can lower their heads when hauling. They can breathe normally and clear their breathing passages.
Kohn addresses why some horses get sick when tied higher: “Some are more sensitive to the head-up posture. With deep breathing, the horse inhales more bacteria.” She advises placing the hay net low rather than high, so the horse drops his head.
Tomlinson says, “The general rule is to tie the horse as loose as is safe for that horse. I generally don’t tie an adult horse that’s used to traveling tightly.”
Kohn describes a vehicle as “a challenging environment. The number of respirable particles is greater. The hay net is in the breathing zone—also dust, molds, ammonia fumes, exhaust and bacteria from hay and bedding.”
Tomlinson adds, “Wet down shavings if you’re in a dry climate. Your goal is to minimize the amount of particulates in the air.”
Monitor the horse’s soundness with regular temperature readings when making long trips. Record normal temperatures before the trip, checking it two or three times a day.
“A single temperature reading is not indicative,” says Tomlinson. “The thermometers can be different, and the technique is different. I need to know what is normal for that horse, with that person, with that thermometer.” He advises recording temperatures for a week before hauling.
Tomlinson notes, “You will be blown away by how much the temperature rises when the horse is in the trailer. It can be 103 when you stop after driving in rush-hour traffic, but it can be 99 to 101 after an hour on the open highway.
Tomlinson adds that a 103-degree reading is normal on especially tough trips where the horse is working hard to keep its balance.
Kohn says “Travel is work—equivalent to walking. It’s an energy-demanding process.” Now, throw in a hot, steamy trailer, which makes them sweat and lose body fluids.
A horse that’s dehydrated in transit can lose body weight. Kohn reports amounts lost as .45 to .55 percent per hour on long trips. “On a 60-hour journey, the horse loses up to 5 percent of his weight.”
In hot, dry climates, Tomlinson offers this suggestion: “We hose the horse down before putting him in the trailer. He’s cooler, and it just feels good. That lasts about 45 minutes.”
Blanketing the horse for transport can cause overheating in any weather. Tomlinson feels horses rarely need blankets while hauling. “They are doing a lot of work in there, even if it’s freezing outside.”
A crowded trailer can also introduce illness. Humidity increases with the number of animals inside, and young horses are often more susceptible to shipping fever. Not to mention that one sick horse can affect others. “If you put a sick horse in a six-horse van, then you get six sick horses out,” says Tomlinson.
Some horsemen rely on immunostimulant medication before the trip. Eqstim and Equimune are two brands that “spike” the horse’s immune system.
Tomlinson names such medications as “one of the instruments in your arsenal of prevention.” However, he cautions, “I am leery of stimulating the immune system of a horse every time you haul.”
Finally, shipping horses in good condition is paramount, because healthier horses can combat fever and recover more quickly.
Taking a Break
On the road, rest stops every four hours give horses a break, and you can check their condition. Keep horses hydrated by offering water. Kohn advises checking hydration through a capillary refill test—look for gums to return to normal pink color in less than 2.5 seconds.
Even a short, 10-minute stop gives horses relief. You can open trailer doors for maximum air circulation, and remove soiled bedding to reduce ammonia fumes.
Tomlinson recommends a “no-instrument” test to check horses in transit: “With my hand, I squeeze the throat to try to elicit a cough. If you squeeze and jiggle the trachea, throughout the throatlatch area, that will elicit a cough if the horse has any phlegm. If he coughs, you get out your stethoscope to see if he’s okay. If I can’t elicit a cough, there’s nothing in there and no problem.”
By taking the time to make sure your horses are healthy, to begin with, by tackling airflow problems in the trailer, and by giving the animals plenty of breaks, you can drastically cut down on shipping fever. “You want a healthy horse in and a healthy horse out,” says Tomlinson.
By Charlene Strickland