Horse Health – Equine Gastric Ulcer Syndrome – Cause and Treatment


Understanding Equine Gastric Ulcer Syndrome (EGUS)

Equine Gastric Ulcer Syndrome (EGUS) describes the ulceration to the lining of the oesophagus, stomach and duodenum in horses.  Although it can affect any horse, it is highly prevalent in foals, mature horses and performance horses. With studies finding 80-90% of racehorses and up to 60% of performance horses affected. Equine Gastric Ulcer Syndrome can significantly affect a horse’s health and performance and in severe cases, cause death.

Why do Horses get EGUS?

Digestive system of a horse functionality

ulcers in performance horses

Cause of Stomach Ulcer is too much acid

First one needs to understand the digestive system of horses. Horses produce gastric acid to break down ingested food. Foals begin producing gastric acid from day 2 and adult horses produce around 1.5 litres (0.4gallons) of stomach fluid per hour. Even when horses are fasting, their bodies continue to produce gastric acid. Ulcers can occur when the lining of the oesophagus, stomach and duodenum are over exposed to gastric acid, also known as gastric splashing. The stomach of a horse is divided into 2 sections  – glandular. and non-gladular.

The glandular area produces hydrochloric acid, which is an enzyme crucial to digestion of food. This region of the digestive system produces substances to help protect the stomach from any effects of the acid. Horses and humans differ, whereby in a horse hydrochloric acid is constantly being produced.

equine gastric ulcer syndrome

Diet and Lifestyle

Secondly, domestication of horses has led to diet and lifestyle changes that leave their digestive systems more prone to gastric ulceration. During food consumption, acidity in this region stays relatively low as both saliva and the ingested food help to neutralise the acid. During periods of fasting, acidity levels have been found to increase in these areas. horses need feed 24/7, if they do not constantly eat, acid will accumulate in the stomach with the lining in the non-glandular area becoming inflamed.

equine gastric ulcer syndrome hindgut and foregut

Feed digests in foregut – ferments in hindgut

The equine digestive tract is unique in that it digests portions of its feeds enzymatically first in the foregut and ferments in the hindgut.The lower section of a horse’s stomach produces acid to help the digestion of food, whilst the upper section of the stomach should not contain any acid at all.

Stabled horses are more prone to ulcers as they are often fed larger meals, once to twice per day. Free grazing/high roughage diets can prevent ulcers due to the constant ingestion of food and high production of saliva.


High levels of stress (which performance and race horses experience) can also contribute to gastric ulcers in horses. Monitoring and managing your horses stress can prevent ulcers.

 What are the Signs and Symptoms of EGUS?

The symptoms can be wide and varied, often presenting similarly to other equine diseases. Many horses with gastric ulcers also do not display any outward signs of the problem.

Clinical signs and symptoms of ulcers can include;

  • Poor appetite
  • Weight loss
  • Poor condition
  • Rough coat
  • Poor performance
  • Behavioural changes
  • Colic


EGUS can be difficult to diagnose. Endoscopic examinations are often needed to officially diagnose EGUS, however, this is often an expensive procedure.

diagnosing ulcer in horses

Diagnosis via Endoscopy

Often a diagnosis is made based on response to treatment with ulcer medication. Signs of improvement are visible as quick as 3 to 4 days after first treating.The goals of treatment are to eliminate clinical signs, promote ulcer healing, prevent ulcer recurrence, prevent complications and reduce cost and duration of treatment.

Ulcer Treatment for Horses

There are various medications available for the treatment and prevention of EGUS. Most of which either help to buffer or neutralise the gastric acid or assist in controlling its secretion.

Horse Ulcer Medication

Omeprazole the approved ‘proton pump inhibitor’ (PPI) which controls gastric acid secretion. This prevents ulcers and allows existing ulcers time to heal without increased acid exposure. Ideal medication for use as both a treatment and as a preventative in smaller doses. Recommended treatment regime is once-a-day for 28 days. Administration is in three different forms (tablet, paste and granules) which should suit even the fussiest of horses.

Sucralfate is both a treatment and preventative. Sucralfate forms a sticky gel which then adheres to and coats ulcers. This forms a barrier which protects the ulcer from further acid production during digestion and allows it to heal. Sucralfate is widely used in humans. The use in horses is not fully understood. Currently, it is not recommended as a lone treatment for gastric ulcers in horses and best-used in conjunction with omeprazole and best fed one hour before grain. For best results administer up to 3 times per day.

Ranitidine,a is another drug used in humans for treatment of ulcers. Similar to other equine gastric ulcer syndrome treatments, it works by inhibiting the production of stomach acid. There is plenty of evidence that indicates this medication affects the acidity levels in horses however there is the need for more evidence that it improves ulcer healing.

Alfalfa: aka Lucerne, known as a good preventative and treatment. We already know that increased roughage prevents ulcer production, but studies indicate that Lucerne may be a more effective acid buffer than standard grass hay.

Preventing Equine Gastric Ulcer Syndrome (EGUS)

Eliminate the negative factors

The first factor in preventing ulcer recurrence is by changing the horse’s diet and lifestyle by increasing a horse’s access to roughage. Change diet to good quality hay such as lucerne or chaff etc. or simply more access to free grazing. High grain diets can contribute to ulcers, so always ensure you are following guidelines and not over feeding.

Manage Stress

Avoiding or apply better long-term management of known stressful situations is a must. This includes; gradual increases in training and graduated changes to diet.  Treating equine gastric ulcers with a smaller dose of gastric ulcer medication pre and post show and a full dose during the show will assist in keeping your horse calm and ulcers at bay. Training needs to be progressive. Long-term use of NSAIDs is a risk factor.

Changing or eliminating negatives goes a long way towards ensuring better health for your horse.As the saying goes  “prevention is better than cure”

How to cure Equine Gastric Ulcer Syndrome

Is there really a cure for ulcers in horses?

Understand that horses naturally produce stomach acid 24/7.  The cure is in controlling the production of acid in a combination of a good diet and administering gastric ulcer medication. Ulcers can take several weeks to heal. It is very common for horses to get them again and again. Be vigilant and observe any behavioural changes, then respond accordingly through a change in diet and medication.

Long-term use of gastric ulcer medication (Omeprazole – PPIs) indicates no known serious side effects (the only downside is the often the cost). Best to discuss long term use with your local Vet.

In conclusion, the best practice to treat and prevent Equine Gastric Ulcer Syndrome is through science (medication) and dietary changes.

References :

PicaVet First European Equine Nutrition & Health Congress
Omeprazole and Sucralfate Racehorse study Orsini JA1Haddock MStine LSullivan EKRabuffo TSSmith G.
Eendoscopic study (Murray, 1989)


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Horse blogger....I am a horsewoman who has a general interest in horses, love talking about horses' and writing about day-to-day horse care issues.

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