Equine Gastric Ulcer Syndrome: Understanding the Two Faces of Gastric Disease

Gastric ulceration is one of the most frequently diagnosed gastrointestinal disorders in horses. Although commonly associated with athletic and performance horses, gastric ulcers are not exclusively a consequence of modern management. Studies have identified gastric lesions even in feral horses, suggesting that ulcer disease has likely existed throughout equine evolution. However, domestication and contemporary management practices appear to have significantly increased its prevalence¹. 

From EGUS to ESGD and EGGD 

Historically, gastric ulceration in horses was grouped under the term Equine Gastric Ulcer Syndrome (EGUS). As diagnostic technology advanced, veterinarians recognized that ulcers affecting different regions of the stomach represented distinct disease entities. 

Today, EGUS is classified into²: 

• Equine Squamous Gastric Disease (ESGD) affecting the non-glandular upper stomach.

• Equine Glandular Gastric Disease (EGGD) affecting the glandular lower stomach.

These conditions differ significantly in pathogenesis, risk factors, and treatment response. 

Why Earlier Studies Underestimated Glandular Disease 

The introduction of gastroscopy revolutionized equine gastric medicine. Early investigations used endoscopes approximately two metres long, which often failed to visualize the pyloric and glandular regions of the stomach. Consequently, squamous ulcers were initially thought to be far more common than glandular lesions¹. 

Longer endoscopes later revealed that glandular ulceration was considerably more prevalent than previously appreciated. 

How Common Are Gastric Ulcers? 

The prevalence of gastric ulcers varies depending on horse population and management practices. 

Studies have reported ESGD in approximately 22% of feral horses¹. In domesticated populations, prevalence rates are substantially higher. Warmblood horses considered clinically healthy showed ESGD lesions in 58% of cases during gastroscopic examination¹. 

Performance horses are particularly susceptible. ESGD prevalence in endurance horses increased from 48% during the off-season to 93% during active competition periods. Approximately 90% of actively racing Thoroughbreds develop squamous gastric ulceration¹. 

The Hidden Burden of EGGD 

Recent studies have highlighted the importance of glandular disease. EGGD prevalence has been reported between 35% and 72% across different equine populations and may exceed ESGD prevalence in some groups³. 

Warmblood horses appear particularly predisposed, and EGGD commonly occurs alongside ESGD⁴. 

Conclusion 

Equine gastric ulcer disease is no longer viewed as a single condition. The distinction between ESGD and EGGD has transformed diagnostic and therapeutic approaches, emphasizing the need for comprehensive gastric evaluation in horses presenting with gastrointestinal or performance-related concerns. 

References

1. van den Boom R. Equine gastric ulcer syndrome in adult horses. The Veterinary Journal. 2022 May 1;283:105830. https://doi.org/10.1016/j.tvjl.2022.105830

2. Sykes BW, Hewetson M, Hepburn RJ, Luthersson N, Tamzali Y. European College of Equine Internal Medicine Consensus Statement—equine gastric ulcer syndrome in adult horses. Journal of veterinary internal medicine. 2015 Sep;29(5):1288-99. https://doi.org/10.1111/jvim.13578

3. Sykes BW, Sykes KM, Hallowell GD. A comparison of three doses of omeprazole in the treatment of equine gastric ulcer syndrome: A blinded, randomised, dose–response clinical trial. Equine Veterinary Journal. 2015 May;47(3):285-90. https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.12287
4. Mönki J, Hewetson M, Virtala AM. Risk factors for equine gastric glandular disease: a case-control study in a Finnish referral hospital population. Journal of veterinary internal medicine. 2016 Jul;30(4):1270-5. https://doi.org/10.1111/jvim.14370