Equine Gastric Ulcer Syndrome

Gastric Ulcers In Horses

Equine Gastric Ulcer Syndrome, also known as EGUS, is a broad term used in equine veterinary medicine to describe ulcerative and erosive diseases of the stomach. “The mucosal lining of the stomach consists of two regions, the squamous mucosa, which is the non-functional lining of the stomach, as well as the glandular mucosa, which secretes gastric acids (hydrochloric acid), pepsinogen, histamine and bicarbonate. These two linings are separated by a border referred to as the margo plicatus.

EGUS can be broken down into two distinct classifications, Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD), with these classifications being based on the affected region of the stomach. 

While a clear grading system exists as a diagnostic tool for squamous ulcers, glandular ulcers have no clear-cut grading system. The ulceration is described according to the anatomical location of the glandular mucosa in which they occur.

The most challenging aspects of equine gastric ulcers is that there is no clear-cut, singular cause. Although racehorses are the most prone to EGUS all horses can be affected. Predisposing factors are wide-ranging and vary from environmental influences, travel, stabling , NSAID (non-steroidal anti-inflammatories such as bute) exposure , diet and competition, to name just a few.

What is the one thing that each of these contributing factors have in common?

All roads lead to stress.

Above all else, EGUS can cause anywhere from mild to extreme discomfort and pain in the horse, resulting in behavioural issues and ultimately reduce performance.

Is a horse simply being irritable or “girthy,” or could there be ulcerations revealing themselves through these behaviours?

Sometimes case presentations can mimic the symptoms of mild to severe colic, especially in performance horses. After they eat, they’ll get painful or they’ll eat a part of their feed and then move away or even lie down, mirroring the symptoms of a mild colic. They may get up and slowly finish their meal, sometimes eating their grain at a slower rate than their hay due to the influx of acid that it causes. This discomfort impacts their performance, and we see these horses often kicking out when their rider puts a leg over them or becoming uncharacteristically temperamental when they’re in the arena. They’re not performing to their abilities because of that gastric pain.

Prevention is key because once the horse is in a disease state it becomes a battle.

Why are Probiotics Good for My Horse?

The microbiome within the hindgut is made up of billions of beneficial bacteria, fungi, protozoa and enzymes that primarily ferment and digest the fibre found in forages and other feedstuffs. These fibre-digesting microbes must be healthy in order for a horse to digest and metabolise the feed he consumes.

Probiotics are live microbes, usually bacteria or yeast, that add to the general microbial population or support the activity and numbers of “good microbes” that naturally reside in the horse. Two types of yeast strains, Saccharomyces cerevisiae and Saccharomyces boulardii, are examples of probiotics used to support nutrient digestibility and utilization in horses. Forward-looking research on specific microflora strains and the microbiome show many areas that could be influenced by a healthy gut, or lack thereof. The health and wellbeing of the microbial world in the gut goes far beyond digestion and feed efficiency, and likely influences every major system of the body.

Managing A Horse With Gastric Ulcers

When gastric ulcers are diagnosed, your vet is likely to prescribe oral omeprazole, a licensed medication, meaning it has been shown to be safe and effective for treatment and prevention of gastric ulcers in horses. Management of a horse with gastric ulcers is extremely important alongside medication, to not only bring about the effective and timely resolution of the ulcers, but also to help prevent further episodes. Key is to remove the stressful stimulus that has triggered the ulcers and to keep to a regular routine.

Feeding is another important consideration. Ideally horses should have free access to forage and water at all times, however if this is not possible, the risk of ulcers can be reduced by making sure the horse goes no longer than 4 hours without access to forage. Limiting the amount of concentrates fed can also help, as can giving a small roughage feed (e.g. chaff or forage) 30 minutes before exercising to help protect the stomach by preventing acid splashing onto the upper stomach.


We have supplements available on both our VetMediUK & The Horse Vet Website.

Equitop Pronutrin Gastric Health Supplement for Horses (vetmedi.co.uk)

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Audevard Ekygard+ Gastric Support For Horses (vetmedi.co.uk)

Gastric | The Horse Vet