Published: October 2020 | Updated: May 2023

We may not think twice about transporting horses on a regular basis, but it’s important to consider the effects of transport on the horse. Though not all horses will outwardly show it, hauling experiences are commonly a stressful experience for them. 

The main source of stress experienced by horses during transport is psychological. However both physical and psychological stress lead to an increase in cortisol (stress hormone) concentrations. Potential stressors associated with transport include the following: 

  • Loading
  • Unloading
  • Separation from familiar environments
  • Confinement
  • Vibration
  • Inadequate ventilation
  • Temperature and humidity
  • Food/water deprivation

The longer the duration of transport, the more stress a horse may experience. In fact, stress-induced pneumonia, commonly referred to as shipping fever, is a potential problem in horses being hauled long distances. 

Studies have also shown that horses undergoing transport are more likely to develop gastric ulcers as well as negative changes in gut microflora which can lead to problems like horse colic or diarrhea

How Does Horse Transport Affect the Equine Microbiome? 

New research suggests that even short trailer trips can negatively impact a horse’s gut microbiota, the bacterial population in the hindgut that helps with proper digestion, immune function, and nutrient and energy production. 

Researchers in one study sampled horse fecal microbiota and found a discernible decrease in the presence of Clostridiales after trailering. This particular species of bacteria appears to be more plentiful in healthy horses, suggesting that negative impact to the equine microbiome may be a problem associated with horse transportation.

Additionally, withholding hay from horses during long-distance trips can lead to a higher incidence of gastric ulcer development. Another study that evaluated the effects of transport showed that horses transported over 500 miles had increased gastric squamous ulcer scores that led to severe ulceration in some horses. 

Should I Feed My Horse Before Trailering?

It’s commonly understood that a lack of forage for long periods of time can contribute to ulcer development in horses. To reduce your horse’s chances of developing gastric ulcers, feeding forage (but not grain) before a journey is a good idea as this will help to buffer acidity and also keep the equine GI tract moving. 

Because of its high calcium content, feeding alfalfa appears to have an additional buffering effect if fed one to six hours before transport. 

Most horses will not need to be fed hay during transport. However, if the journey will take six hours or longer, it is recommended to provide hay in the trailer. Keep in mind that feeding hay during trailering does come with some risks, one being pneumonia, which can occur as a result of inhaling dust particles and not being able to eat in a natural head-down position. It’s also worth noting that some horses appear to have an increased risk of choke (esophageal obstruction) while eating hay during transport. 

On long trips when the benefits of hay may outweigh the risks, soaking it in water beforehand can help reduce the amount of dust particles that the horse could possibly inhale. 

How Can I Relieve Stress in Horses During Transport? 

Eliminating horse transportation altogether is obviously not reasonable or practical for most people, but there are proactive steps you can take to reduce stressful situations associated with hauling. First, make sure your horse is first familiarized with loading and unloading in the trailer before expecting him to take a long ride in it, and likewise, only use shipping boots or wraps if the horse is accustomed to them. 

Strive to make your trailer as comfortable as possible for your horse as well. Trailer mats are a must, but adding bedding can reduce strain on the horse’s legs and joints. Ensure there are working lights inside the trailer for night time hauling. 

Another priority is making sure that your trailer has adequate ventilation in order to avoid added heat stress. Open stock trailers will have plenty of ventilation, but in closed trailers, roof vents should be open toward the rear of the trailer to allow air inside the trailer to escape. If the side windows are open, this will help create a steady flow of air through the trailer while in motion. 

On very warm days, opening roof vents to the front will reverse the air flow and force more fresh air into the trailer. However, this will also create more dust that horses could inhale or that could get in their eyes. As with hay, wetting down trailer bedding will help control dust and airborne debris.

For safety reasons, use screens or bars on windows; a horse should never be allowed to stick his head out an open window during travel. 

Though it goes against common practice, studies also show that horses should not be tied during transport. When they are tied with their heads up, cortisol levels tend to be higher than horses that are hauled loose. Horses tied during transport cannot effectively clear their airways, which greatly increases their chances of respiratory infection or shipping fever.

For longer trips, plan to stop and offer water to your horse every 4-6 hours (or every 3-4 hours in hot weather). Also offer hay during these stops, if possible. 

Trailer orientation, as far as facing toward or away from road travel, has also been identified as a potential source of stress in horses. Studies suggest that horses facing away from travel tend to experience less stress and also have a better ability to clear their airways and also adjust their posture. However, while most horses appear to prefer this orientation, others may show signs of greater stress if forced to ride backward. Therefore, deciding which orientation to use should be made on a case-by-case basis. 

Other tips for reducing transport stress in horses include:

  • Providing a hauling buddy. 
  • If possible, don’t haul ill horses.
  • Plan your route to avoid prolonged stationary periods in traffic. The lack of airflow, combined with sun can make a trailer 20 degrees warmer inside than outside.
  • When hiring a commercial transport company for long-distance hauling, thoroughly vet them first to ensure they are experienced and competent.

Finally, to address changes in the gut microbiome which can occur as a result of horse transport stress, consider feeding an equine probiotic paste both several days before long transport, as well as a day or two afterward to help restore beneficial bacteria in the gut. 

Using these high-powered probiotics for horses can make the entire horse transportation experience the best it can be for both you and your horse.

Read More:

Reduce Your Horse’s Transport Stress

Effects of Transport on the Microbiota of Healthy Adult Horses

Transportation Related to Equine Gastric Ulcers

Transport Stress in Horses

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