Equine Gastric Ulcers: Signs, Treatment & Prevention

If your horse has lost its edge — picking at feed, dropping condition, getting cinchy or sour under saddle, or just not performing the way it should — gastric ulcers are one of the first things worth ruling out. They're remarkably common: research suggests well over half of performance and racehorses have ulcers, with rates in some racing populations reported above 80–90%. Even pleasure horses are far from immune.

The good news is that ulcers are very treatable once they're found. The hard part is that the signs are easy to mistake for "attitude," "being fussy," or a training problem — so many horses stay uncomfortable for months before anyone looks at the stomach.

A horse's stomach produces acid continuously, whether or not there's food in it — an evolutionary fit for an animal built to graze almost around the clock. When that acid contacts the stomach lining without the buffer of constant forage, it can erode the tissue and create ulcers. The umbrella term is Equine Gastric Ulcer Syndrome (EGUS), and it's now usually split into two distinct diseases, in two different parts of the stomach:

• Equine Squamous Gastric Disease (ESGD) — ulcers in the upper, non-glandular part of the stomach, which has little natural protection and is vulnerable when acid splashes upward during exercise or after long gaps without food.
• Equine Glandular Gastric Disease (EGGD) — ulcers in the lower, glandular part, where acid is made. This region normally protects itself, so glandular disease reflects a breakdown of that defense, with stress and certain medications playing a bigger role. It's typically harder to treat.

There's no single giveaway — ulcers usually show up as a cluster of subtle changes:

Any one of these has other possible explanations. But when several appear together — especially in a horse in training, traveling often, or on a grain-heavy diet — ulcers move up the list.

For a closer look at each one, see our full guide to the signs and symptoms of equine ulcers.

Signs can point toward ulcers, but they can't confirm them — and they can't tell squamous disease from glandular disease, which matters for treatment. The only definitive diagnosis is gastroscopy: after a fasting period (typically overnight), a veterinarian passes a long endoscope into the stomach to look directly at the lining and grade what's there.

Scoping does two important things. It confirms whether ulcers are actually the problem rather than something else, and it sets a baseline so you can re-scope later and verify the ulcers have truly healed — not just that the horse seems a bit better.

The cornerstone of treatment is omeprazole, a proton-pump inhibitor that suppresses acid production and lets the lining heal. It's the best-studied, most reliable option, and it's the active ingredient in the FDA-approved equine products:

• GastroGard — the higher, treatment-strength dose used to heal active ulcers. It's a prescription medication, used under veterinary direction.
• UlcerGard — the same drug at a lower, preventive dose, used to protect horses around predictable stressors like shipping or competition. It's available over the counter.

A typical course runs about 28 days, followed by a re-scope to confirm healing. Squamous ulcers usually respond well. Glandular disease is more stubborn and often needs a longer course or a combination approach — your vet may add sucralfate (which coats and protects the lining) or other medications. This is exactly why a plan should be built with a veterinarian rather than guessed at: the right drug, dose, and duration depend on what's actually in the stomach.

Going deeper: see our step-by-step treatment protocol, a breakdown of what treatment costs, and affordable omeprazole options.

Because the problem is fundamentally acid plus an empty stomach, most prevention comes down to keeping forage moving through and reducing the stressors that drive glandular disease:

• Maximize forage. Near-constant access to hay or pasture buffers stomach acid and mimics natural grazing. Long gaps without food are a primary risk factor.
• Feed before you ride. A little hay — alfalfa works well as a buffer — before exercise reduces acid splashing up into the vulnerable upper stomach.
• Cut the grain and starch. High-starch concentrates increase ulcer risk. Lean on forage and fat for calories where you can.
• Maximize turnout, reduce stress. Confinement, isolation, heavy training, and frequent transport all raise risk.
• Be careful with NSAIDs. Bute and similar anti-inflammatories can contribute to glandular ulcers; use only as directed by your vet.
• Protect around known stressors. A preventive dose of omeprazole during shipping or competition can keep ulcers from forming at all.

For the full playbook, see our guide to preventing ulcers through feeding and management.

If your horse is showing several of the signs above — especially weight loss, recurring colic, or a clear drop in performance or appetite — it's worth a veterinary conversation. A vet can advise on whether to scope, build the right treatment plan, and prescribe the treatment-strength medication active ulcers usually need. Catching ulcers earlier almost always means a shorter, easier recovery.