07/07/2026
Great research being done on EGUS and pre-exercise feeding of hay.
If you have ever been told to make sure your horse has hay before a ride, you were given advice that makes intuitive sense and has some scientific backing but a researcher at the University of Queensland (Australia) wants to find out whether it actually works the way we think it does, and her findings could change how performance horses are managed around the world, Piper Klemm writes.
Researcher Stephanie Bond is conducting a two-year study, funded by the Grayson-Jockey Club Research Foundation, examining how different feeding routines before exercise affect acid splash inside a horse’s stomach during work. The condition at the center of her research is Equine Gastric Ulcer Syndrome, or EGUS, specifically a form of it called Equine Squamous Gastric Disease, which affects the upper portion of the horse’s stomach.
Here is the basic problem: the upper portion of the horse’s stomach is not built to handle acid. It lacks the natural protective lining that the lower portion has. Under normal circumstances, it maintains a relatively neutral pH. But during exercise, the physical compression of the stomach causes acidic fluid to splash upward into that unprotected upper region and if that happens repeatedly, ulcers develop. The prevalence numbers are striking: during active training, squamous disease has been reported in up to 100 percent of Thoroughbred racehorses.
The conventional wisdom has been that feeding hay before exercise creates a kind of fiber buffer inside the stomach that reduces the acid splash effect. This has been shown to work in horses at rest. What Bond’s study is designed to determine is whether it actually works during exercise, which is a meaningfully different physiological state and one where previous research methods have been unreliable.
The innovation in this study is the measurement tool. Rather than using the traditional nasogastric probe, whose position inside the stomach is uncertain and prone to shifting, Bond is using a wireless pH capsule originally developed for human medicine that attaches directly to the stomach lining and transmits continuous readings from a fixed, known location. This makes the data considerably more reliable than what previous research has been able to produce.
Horses in the study will be tested under three pre-exercise conditions: no feed, chaff, and hay, allowing direct comparison of how each protocol affects acid splash during actual work.
For every horse owner, trainer, and barn manager who has wondered whether that morning hay flake is �really making a difference before a ride, this study is working toward a science-based answer.
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