Researchers have long known that transportation can be stressful for horses—not only for their minds but also for their bodies. Still, scientists haven’t yet zeroed in on all the ways travel impacts horses’ body systems. They have proven that transport negatively impacts the immune function of other species, including cattle and swine, but little is known about the horse, and there’s no work investigating the impact on senior horses.

So recently, Alessandra Campana-Emard, a student at the University of Kentucky (UK) working under the direction of Amanda Adams, PhD, an associate professor at UK’s Gluck Equine Research Center; and colleagues including Suzanne Schindler, a veterinary student at Lincoln Memorial University, in Harrogate, Tennessee, set out to determine how transport impacts horses’ immune systems. Specifically, they studied a group of horses that could be particularly at risk when immune function is diminished: senior horses.

“Senior horses, comprising a significant percentage of the equine population, travel frequently … which is of concern for two reasons,” Campana-Emard said. “First, it has been shown that, with increasing age, there is a decline in immune function and an increased production of inflammatory cytokines,” which results in a chronic, low-grade state of inflammation known as inflamm-aging.

“Second, it is imperative to understand the impact of age and traveling stress on immune function to determine if the transportation of older horses may increase their susceptibility to infection and, if so, for how long,” she said