Gastric ulcers are among the most underestimated conditions in horses: studies in sport and racehorses find them in more than half of the animals scoped, while the signs are so vague that owners often overlook them for months. A horse with gastric ulcers is rarely acutely ill — it performs just a bit worse, eats just a bit slower, reacts just a bit more sharply to the girth. This guide helps you piece the puzzle together sooner and shows what you can change about stable management and feed.
What Happens in the Stomach
The horse's stomach is small and continuously produces gastric acid — a legacy of life on the steppe, where a horse eats small amounts of fiber almost around the clock. That chewing produces a constant stream of saliva, and saliva buffers the acid. When eating stops, acid production just keeps going.
The lower part of the stomach wall is protected against this by a mucous lining; the upper part isn't. If acid sloshes against that unprotected upper part on an empty stomach — for example during work in trot and canter — it damages the lining and ulcers develop. Vets sum this up under the term EGUS, Equine Gastric Ulcer Syndrome.
The Signs: Small on Their Own, a Pattern Together
None of these signs on its own proves a gastric ulcer, but the more of them coincide, the stronger the suspicion:
- Poor or inconsistent appetite — especially leaving concentrate feed or eating through it slowly.
- Sensitivity when girthing up or grooming the belly — ears back, tail swishing, snapping.
- Reduced performance — less forward, shorter through the topline, resistance that wasn't there before.
- Dull coat and poor condition despite good feed.
- Recurring, mild colic — vague episodes of abdominal pain that resolve on their own.
- Behavior change — quicker to irritate, withdrawn around handling, stall-walking or cribbing.
Where It Comes From
| Risk Factor | Why It Matters |
|---|---|
| Long periods without forage | Empty stomach means unbuffered acid against the unprotected stomach wall |
| Lots of concentrate feed, little fiber | Starch means less chewing and saliva, and further acidifies the stomach contents |
| Training on an empty stomach | In trot and canter, acid sloshes up against the upper part of the stomach |
| Stress: transport, stable changes, shifting herd groups | Stress hormones reduce blood flow to the stomach lining |
| Stall rest and little turnout | Less grazing, less movement, more stress at the same time |
The classic risk profile is the well-meaning competition routine: concentrate feed in two large portions, hay at fixed times, training in the morning before feeding, and regular transport. Each element is defensible on its own; the sum is exactly what a stomach doesn't want.
Only the Vet Can Give Certainty
The only way to confirm gastric ulcers is a gastroscopy: the vet examines the stomach wall with a camera, for which the horse needs to be fasted for several hours. Treatment uses prescription acid-suppressing medication and works well, but without addressing the underlying causes, the ulcers come back. Experimenting with remedies yourself without a diagnosis isn't advisable: the signs above also fit other conditions, and you'd be masking the real problem. If you're unsure, also read when to call the vet.
What You Can Change Yourself
- Forage almost unlimited, or at least frequent. Aim for short gaps between feedings; a slow feeder or a small-mesh hay net stretches out a portion.
- A few mouthfuls of forage before riding. A small bit of hay or alfalfa before training lays down a buffer mat in the stomach — alfalfa buffers especially well because of its calcium and protein.
- Less starch per meal. Spread concentrate feed over more, smaller portions, and take a critical look at whether the amount is even needed — see how to feed your horse well.
- As much turnout and free movement as the situation allows. Grazing is the natural state of the horse's stomach.
- Limit avoidable stress. A stable herd, a calm neighbor, and a predictable daily routine do more for the stomach than many a supplement.
In Short
- Gastric ulcers are common, especially in sport horses, and produce vague signs: appetite, girth sensitivity, reduced performance, dull coat, mild colic episodes.
- The cause is almost always a combination: long gaps without food, a lot of starch, training on an empty stomach, and stress.
- Only a gastroscopy gives certainty; treatment runs through the vet.
- Management is half the solution: continuous forage, forage before riding, less starch per portion, more turnout, less stress.
See also: How to Feed Your Horse Well · When to Call the Vet · Colic in Horses: Recognizing Symptoms and What to Do Right Away · Glossary: gastric ulcers (EGUS) · Level: Considering Your Own Horse