Horses with gastric ulcers need a diet built around continuous forage access, limited starch, and feeding patterns that keep stomach acid in check. Gastric ulcers affect anywhere from 25% to 93% of horses depending on discipline and workload, so dietary management is one of the most practical tools owners have. The good news is that relatively simple changes to what, when, and how you feed can make a meaningful difference in both healing and prevention.
Why Diet Matters for Gastric Ulcers
A horse’s stomach produces acid continuously, whether it’s eating or not. In a natural grazing pattern, the constant chewing generates saliva, which contains bicarbonate that buffers that acid. When horses go hours between meals, or eat large grain-heavy meals, acid pools in the upper (squamous) portion of the stomach, which has no protective mucus lining. During exercise, stomach contractions can splash acid onto this vulnerable tissue. The result is erosion and ulceration.
Ulcers in the lower glandular portion of the stomach have a somewhat different cause, involving breakdown of the protective mucus barrier, but dietary management helps with both types. Competition and training significantly raise the risk: ulcer prevalence in endurance horses climbs from about 48% in the off-season to 93% during competition season.
Forage First: The Foundation of an Ulcer Diet
Forage should make up the vast majority of the diet for any horse with ulcers. Free-choice hay or pasture keeps the stomach buffered, stimulates saliva production, and creates a fibrous mat that sits on top of gastric fluid. This mat physically prevents acid from splashing up onto the unprotected squamous lining, which is especially important before exercise. Feeding a small hay meal before riding gives your horse that protective layer right when it matters most.
Alfalfa hay is particularly useful for ulcer-prone horses. It contains roughly twice the calcium of a typical grass hay (about 14 mg per gram of dry weight, compared to around 7 mg/g in bromegrass). That calcium buffers stomach acid, raising the pH of gastric contents for up to five hours after feeding. Research from the American Journal of Veterinary Research found that horses fed an alfalfa-grain diet had significantly higher stomach pH for the first five hours post-feeding compared to horses on grass hay alone.
One caveat with alfalfa: the same study noted that starting around seven hours after feeding, stomach acid levels rebounded and actually increased, persisting for at least 12 hours. This means alfalfa works best when fed in smaller, more frequent meals rather than one large serving. Mixing alfalfa with grass hay, or offering it at strategic times (such as before exercise or before a long gap between feedings), lets you take advantage of the buffering without triggering a rebound.
Limiting Starch and Sugar
High-starch feeds are one of the biggest dietary risk factors for gastric ulcers. Starch that reaches the stomach ferments, producing volatile fatty acids that damage the squamous lining. Large grain meals also stimulate a surge of gastric acid production. Penn State Extension recommends keeping sugar and starch intake below 1 gram per kilogram of body weight per meal, and below 2 grams per kilogram of body weight per day. For a 500 kg (1,100 lb) horse, that means no more than 500 grams of combined sugar and starch in a single meal.
In practical terms, this means cutting back on sweet feeds, oats, corn, and barley. If your horse needs calories beyond what forage provides, look for low-starch commercial feeds (often labeled “low NSC”) or replace grain calories with fat and fiber sources. Many feed companies now make products specifically designed for ulcer-prone horses, with starch levels well under 15%.
Beet Pulp as a Fiber Alternative
Beet pulp is worth considering as a calorie source that sidesteps the problems of grain. Often called a “super fiber,” it delivers more energy than typical hay while remaining low in starch. A study in warmblood horses found that those offered beet pulp had a lower risk of developing squamous ulcers compared to those that were not. Researchers speculated this may relate to beet pulp’s effects on saliva production, gastric pH, or the microbial environment in the stomach, though the exact mechanism hasn’t been pinned down yet.
Beet pulp is commonly soaked before feeding, though soaking isn’t strictly necessary. It can replace a portion of your horse’s grain ration or serve as an additional fiber source alongside hay. Start with a pound or two per meal and adjust based on your horse’s caloric needs.
Fat for Calories, Not Necessarily for Healing
Adding fat to the diet is a smart way to provide energy without increasing starch. Vegetable oils and stabilized rice bran are common choices, and they’re calorie-dense enough to support performance horses on reduced grain. However, don’t expect oil itself to heal ulcers. A controlled study published in the Journal of the American Veterinary Medical Association tested corn oil, refined rice bran oil, and crude rice bran oil at 240 mL per day for six weeks and found no protective effect against ulcer formation in the squamous stomach.
Fat is still valuable in the overall feeding plan because it lets you lower starch intake while maintaining body condition. Just think of it as a tool for meeting energy needs, not as an ulcer treatment on its own.
Supplements That Show Promise
Among the many gastric supplements marketed for horses, pectin-lecithin complexes have some of the stronger evidence behind them. A clinical trial of 24 horses found that a 10-day course of a pectin-lecithin supplement produced a statistically significant reduction in ulcer lesions in both the squamous and glandular regions of the stomach. Untreated horses showed no improvement or worsened during the same period. These supplements are thought to form a gel-like coating that protects the stomach lining.
Other supplements you’ll encounter include sea buckthorn berry extracts, antacid pastes, and various herbal blends. Evidence for most of these is thinner. If you choose to use a supplement, treat it as one piece of the puzzle alongside proper feeding management, not a replacement for it.
Feeding Schedule and Meal Size
How often you feed matters as much as what you feed. The single most damaging pattern for ulcer-prone horses is long stretches without forage. After about five to six hours without food, stomach pH drops sharply, and acid begins eroding unprotected tissue. The goal is to minimize these gaps.
- Offer hay free-choice whenever possible. Slow-feeder nets can extend eating time for horses that bolt through hay quickly.
- Split grain meals into the smallest portions you can manage. Three or four small feeds are better than two large ones. Each grain meal should stay under the 1 g of starch per kg body weight threshold.
- Feed forage before exercise. Even a small flake of hay 20 to 30 minutes before work creates the fibrous mat that buffers acid splash during movement.
- Feed forage before grain. Hay eaten first slows gastric emptying and cushions the impact of starch reaching the stomach.
For horses that are stalled overnight, the gap between the evening meal and morning feed is often the longest fast of the day. Adding a late-night hay feeding, using a slow feeder, or providing a larger evening hay ration can help bridge that window.
Pasture vs. Stall Management
Horses on pasture generally have lower ulcer rates than stalled horses, and the reason is straightforward: they graze almost continuously. If turnout is an option, maximize it. Even a few extra hours of grazing per day reduces the time the stomach sits empty. Horses that live on pasture full-time with minimal grain feeding have the lowest ulcer risk of any management style.
When full turnout isn’t possible, mimic the grazing pattern as closely as you can with frequent small forage meals and slow feeders. The closer your horse’s feeding pattern resembles continuous grazing, the better its stomach lining is protected.
Putting It All Together
A practical ulcer-friendly diet for most horses looks like this: free-choice or near-constant access to mixed grass and alfalfa hay, minimal grain replaced with low-starch alternatives like beet pulp and added fat, meals split into small frequent feedings, and hay offered before every exercise session. For horses in heavy work that need significant calories, stabilized rice bran, beet pulp, and vegetable oil can cover the energy gap without pushing starch intake over safe limits. A pectin-lecithin supplement can provide additional mucosal protection during active healing periods.
Keep in mind that diet alone may not fully resolve existing ulcers, especially severe ones. Veterinary treatment with acid-suppressing medication is often needed to heal active ulceration, with dietary changes playing a critical role in preventing recurrence once treatment ends. The feeding strategies outlined here are what keep ulcers from coming back once the initial damage is addressed.