10 Things You Might Not Know About Equine Gastric Ulcers

  • by Amy Young

Gastric ulcers are common and can affect any equid. Whether your horse actively competes on a show circuit or spends leisure time with you on the trail, gastric ulcers can ruin the fun. The availability of seemingly contradictory information can make an already frustrating situation worse. To provide some clarity, we teamed up with UC Davis equine internal medicine specialist Dr. Rana Bozorgmanesh for the most up-to-date information on equine gastric ulcers.

1. Horses produce stomach acid 24 hours a day. Horses’ digestive systems are designed to support continuous grazing, so their stomachs secrete acid continuously, even when they are empty. In the absence of constant forage, that acid can build up and cause ulcers. This is why free-choice hay, frequent foragebased meals, and access to pasture are important.

2. Even the most well-managed and calm horses can have gastric ulcers. Although high-strung and high-performance horses are considered the poster children for gastric ulcers, they can affect recreational horses and easy keepers too. Despite diligent management, stressors such as travel, new environments, or changes in herd dynamics can contribute to gastric ulcers in even the calmest horses.

3. Gastric ulcers may cause a decline in performance, but owner-reported clinical signs often do not accurately predict EGUS. Reluctance to go forward (and other attitude changes) under saddle, shortened stride length, and other performance issues are often reported before noticeable changes in appetite or weight (Torcivia and McDonnell, 2025). However, a recent study highlighted limitations of nonspecific signs such as “poor performance” for EGUS screening (Frippiat et al. 2025).

4. Gastric ulcers do not always cause clinical signs. Just because your horse seems fine doesn’t mean they are ulcer-free. Research 

Three wild horses standing together on the plains
Feral and wild horses can develop gastric ulcers but may not exhibit related clinical signs.

has shown that adult horses with gastric ulcers can be asymptomatic (Luthersson et al., 2009). Interestingly, reports have detailed gastric ulcers in feral and wild equids, including those housed in zoos and parks, but none of the affected animals exhibited clinical signs (van den Boom 2022, Lamglait et. al, 2017, Ward et al. 2015).

5. Gastroscopy is the only way to definitively diagnose the presence, type, and severity of ulcers. Although poor performance and weight loss may imply ulcers, only gastroscopy can provide an actual diagnosis. Gastroscopy involves looking inside the stomach with a camera. Horses must be fasted prior to the procedure to ensure that the stomach is empty for optimal visibility. Other diagnostic methods have been investigated but none has demonstrated the specificity or sensitivity necessary to replace gastroscopy for diagnosis of gastric ulcers (Vokes et al. 2023, van den Boom 2022).

closeup of horse's nose as it is eating alfalfa hay

6. Feeding hay before exercise can help protect the stomach. Feed a small flake of hay before riding to help protect your horse’s stomach. This provides a physical barrier and buffering effect to acid that splashes into the squamous region of the stomach during exercise. Alfalfa is particularly effective since its high levels of calcium and protein provide additional buffering (Camacho-Luna et al. 2018). However, other fibrous feeds, such as grass hay, can be beneficial. The act of chewing also stimulates saliva production, which helps to neutralize stomach acid.

7. The prevalence of gastric ulcers does not differ between horses that crib and those that do not. To date, research has failed to link this common stereotypy and equine gastric ulcer syndrome. The presence of ulcers in cribbers is likely associated with stress, which also underlies the behavior. Since cribbing does not stimulate saliva production, it is unlikely horses do it to relieve stomach pain (Moore-Colyer, 2024).

8. Gastric ulcer medications are not all created equally. GastroGard® and UlcerGard® are the only medications approved by the United States Food and Drug Administration (FDA) for the treatment and prevention of gastric ulcers, respectively. Compounded drugs are not regulated, so you don’t always know what you are getting. They can vary in pH, bioavailability and effectiveness (van den Boom 2022). Although compounded medications are often less expensive, inaccurate or ineffective ingredients can prolong treatment and lead to additional veterinary visits, which end up costing more in the long run.

9. Ulcers can return after treatment ends. Relapses are common if management changes are not implemented. One study showed that gastric ulcers can return as soon as 3 days after treatment is discontinued (Shan et al. 2022). Ensure constant access to forage, reduce stress, and plan exercise appropriately to prevent recurrence.

10. Ulcers are not always to blame. If your horse isn’t responding to ulcer treatment, other issues like delayed gastric emptying or inflammatory gut conditions could be to blame (Sykes et al. 2015, Hewetson et al. 2022). Work with your veterinarian to determine the underlying cause of your horse’s discomfort.

References

Torcivia C, McDonnell SM. Behavioral Signature of EquineGastric Discomfort? Preliminary Retrospective Clinical Observations. Animals 2025:5;88.

Frippiat T, Bonhomme M, Dyson S, Votion DM. Evaluation of Owner-Reported Clinical Signs and Fecal Occult Blood Tests as Predictors of Equine Gastric Ulcer Syndrome in Competition Dressage Horses. JVIM 2025;39:e70248.

Luthersson N, Nielsen KH, Harris P, Parkin TDH. Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark. Equine Vet J 2009;41:625–630.van den Boom, R. Equine gastric ulcer syndrome in adult horses. Vet J 2022;283-4:105840.

Lamglait  B, Vandenbunder-Beltrame M, Trunet E, Lemberger K. Description of gastric ulcers and of their suspected, associated risk factors in deceased wild equids at the Réserve Africaine de Sigean, France (2010-2016). J Zoo and Wildlife Med 2017;48(3):668-674.

Ward S, Sykes BW, Brown H, Bishop A, Penaluna LA. A comparison of the prevalence of gastric ulceration in feral and domesticated horses in the UK. Equine Veterinary Education 2015;27(12):655-657.

Vokes J, Lovett A, Sykes B. Equine Gastric Ulcer Syndrome: An Update on Current Knowledge. Animals (Basel) 2023 13(7):1261.

Camacho-Luna P, Buchanan, B, Andrews, FM. Advances in Diagnostics and Treatments in Horses and Foals with Gastric and Duodenal Ulcers. Vet Clin NA: Equine Practice 2018;34(1): 97-111.

Moore-Colyer, M. Equine gastric ulcer síndrome: is feeding key? UK-Vet Equine 2024;8(S2): S3-8.

Shan, R, Steel, C, Sykes, B. The Impact of two Different Withholding Periods of Omeprazole and the Use of a Nutraceutical Supplement on Recurrence of Equine Gastric Ulcer Syndrome in Thoroughbred Racehorses. Animals (Basel) 2023;13(11):1823.

Sykes BW, Hewetson M, Hepburn RJ, Luthersson N, Tamzali Y. 2015. European College of Equine Internal Medicine Consensus Statement – Equine Gastric Ulcer Syndrome in Adult Horses. J Vet Intern Med 2015;29(5):1288-99.

Hewetson, M, McGuire, C. 2022. Equine squamous gastric disease and delayed gastric emptying – The chicken or the egg? Equine Vet Educ 2022;34:460-466.