“Transport and fasting definitely have an effect on stomach ulceration—more than just fasting alone,” said Barbara Padalino, PhD, associate professor at the University of Bologna, in Italy, one of the researchers on the study.

“Feeding hay before the journey helps absorb acid, especially when it splashes in the stomach, so it has a sort of protective role,” she said. “Plus, it leads to more antioxidants in the blood, which helps balance out free radicals. So just give horses some hay and water a few hours before loading—and leave it available all the way up to the time of loading—so they can go with a full stomach.”

Horse Transport and Oxidative Stress

Scientists already know travel is stressful for horses, even over short distances, Padalino said. But having studied the effects of transport on horses for more than a decade, she suspected shipping them on an empty stomach would also increase oxidative stress.

At a molecular level, horses—along with humans and other animals—experience oxidative stress when free radicals start to outnumber the protective antioxidant mechanisms. This imbalance can have physiological impacts on the body, including the development of gastric ulcers, she said.

Different Feeding Regimes Prior to a 12-Hour Trip

To examine the effects of feeding prior to travel, Padalino and her fellow researchers worked with 26 healthy mares belonging to the Charles Sturt University teaching and research herds in Wagga Wagga, Australia. The 14 Standardbreds, 10 Thoroughbreds, and two Warmbloods ranged in age from 4 to 20 years and lived on pasture with additional alfalfa hay provided.

The researchers planned a 12-hour, 880-kilometer (547-mile) overnight road trip for the horses, 13 at a time in the same 15-horse trailer on the same itinerary, driven by the same driver two nights in a row.

Before the trip, the team fed each horse 2.5 kilograms (4.4 pounds) of alfalfa hay, but the timing of the meal varied according to the study group. Seven horses received the hay an hour before travel, another seven horses received it six hours before travel, and the remaining 12 horses had their last meal a full 12 hours prior to travel. None of the horses received food or water during the trip, which increased the stress (the Australian code of standards and guidelines for live animal transport allow for this).

Four hours before loading, the researchers carried out clinical examinations of each horse and performed blood tests to check standard blood parameters and total plasma antioxidant status. They repeated these procedures the next morning as the horses were unloaded, then again eight hours later, and once again two and a half days later.

The team also performed gastroscopies on each horse, with the animal under sedation, a day before traveling, just after arriving, and 2 ½ days later.

Antioxidants Lowest, Ulcer Scores Highest in Horses Fasted Pre-Travel

By the time they arrived at their destination, 14 horses had developed moderate to severe squamous mucosa ulcers, Padalino said. Horses that had fasted for 12 hours before departure showed the highest combined (squamous and glandular) ulcer scores.

Free radicals were higher just after unloading than they were before traveling, regardless of the study group, she said. In fact, the free radical levels were consistently higher just after travel, or eight hours later, compared to before travel or two days later.

However, at the time of loading up for travel, the horses that were fed one hour before departure already had significantly higher plasma antioxidant levels than those fed 12 hours before, Padalino said. That might have helped the horses balance out the free radicals created during transport.

By contrast, the horses fed six or 12 hours before travel had lower plasma antioxidant levels at the time of loading, with those fasted for 12 hours having the lowest, she said.

Somewhat surprisingly, said Padalino, the plasma antioxidant levels of the horses fed one hour before travel dropped during the 12 hours of transport, whereas those of the other groups increased. With the one-hour group, the food reserves might have been so helpful in coating the stomach that they didn’t need to call in the support of antioxidants, she explained.

The researchers didn’t find any direct links between antioxidant levels and gastric ulcers in this study, Padalino said, which might have been due to the small study numbers.

The findings suggest feed management prior to a long journey might affect both ulceration and oxidative balance, she said, noting that additional studies are needed to provide a greater understanding of the links.

Owners should feed their horses hay—not concentrated feeds—prior to travel, she added. Hay takes longer to digest and coats the stomach better, with a low acidic content.

The Journal of Equine Veterinary Science article, “

Effects of Transport and Feeding Strategies Before Transportation on Redox Homeostasis and Gastric Ulceration in Horses,” was published online in March 2023.