Equine gastric ulcer syndrome

Equine gastric ulcer syndrome (EGUS) refers to the presence of ulcers (a localized erosion) in the stomach of the horse. 

The horse's stomach is divided into two parts: the upper half has a squamous lining, while the lower half has a glandular lining; the cells of this lower half produce hydrochloric acid.  Ulcers are most commonly found in the squamous part of the stomach.


Precipitating causes of EGUS

Unlike humans, horses produce hydrochloric acid constantly, as they have evolved to continually graze.  This means that in between periods of grazing, the acidity in the stomach becomes very high.  This is why prolonged time between meals, or food deprivation predisposes to the development of gastric ulcers.

Other suggested causes include intensive exercise, delayed gastric emptying, high-starch diets, stress, severe illness, and exposure (particularly to prolonged or high doses) to non-steroidal anti-inflammatory drugs.

Gastric ulcers in horses are quite common.  The current estimate of prevalence in racehorses is 90%, in foals 50%, and in sport and leisure horses 37-66%.



Clinical signs of EGUS include bruxism (grinding teeth), salivation, colic, poor appetite, poor performance, altered behaviour and weight loss.  In foals, diarrhoea is also a sign.  In some cases, the ulcers can perforate.  This is more common in foals and signs of gastric rupture can include all of the above, recumbency and sudden death.  There are several other possible sequelae to EGUS including gastro-oesophageal reflux, fibrosis and stricture formation.  Most of these are more commonly seen in foals.

Endoscopy of the stomach provides a more definitive diagnosis and involves your vet passing a gastroscope into the stomach to visually check the lining.  We can provide this service at Totally Vets Awapuni.



The aim of treatment is to decrease the acidity in the stomach.  Treatment with a drug called Omeprazole (Gastrozol® and others) inhibits the secretion of the acid.  It is very effective but also costly.  Sometimes only a short 14-day course is required and then the horse can be managed with other changes.  Some horses require ongoing treatment, tapered to the lowest effective dose.

Sucralfate can also be used.  This product sticks to the ulcer to protect it against acid.  It is more commonly used in foals.  This and several other products are only effective if given on an empty stomach making them less useful as food deprivation is contra-indicated in EGUS!



Preventing development of ulcers revolves around avoiding triggering factors.  Feed little and often (ideally 4-6 meals a day if not on pasture) and at least 75% of the diet should be roughage.  Avoid periods of time with nothing to eat, prolonged confinement, and be aware of the signs of ulcers, particularly in horses that are exposed to the factors discussed previously.

Act quickly if you notice any of the clinical signs listed by calling your vet and don't hesitate to contact us at the Totally Vets Awapuni branch for more information.


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