Equine Gastric Ulcer Syndrome – An Overview


Equine Gastric Ulcer Syndrome (EGUS):

Horses have evolved over the thousands of years and have had many adaptations to the changing environments; however, modern day activities have tested their bodies to the maximum. But with ever evolving technology and modern techniques such conditions can be resolved more effectively.

According to recent research in the western world, (with the use of gastroscopy) approximately 80-90% of racehorses, over 60% in competition horses, up to 50% of leisure horses and 50% of foals have shown to have gastric ulcers with a range of severity1. Equine Gastric ulcers can be caused by excessive exposure of the mucosal lining of the stomach to acidic gastric juice. This causes erosion of the lining resulting in ulceration and even bleeding. Ulcers are commonly seen in the upper squamous lining as this has limited protection against acid injury.

What Causes EGUS?

Causes of EGUS include anatomy of the stomach, diet, restricted feed intake and periods of starvation, high grain diets, high speed exercise, stress and the use of non-steroidal anti-inflammatories (NSAIDs)2 During exercise, increased pressure in the abdomen compress the stomach, pushing acid contents up into the squamous region of the stomach. On-going exposure leads to erosion of the delicate mucosa creating ulceration. Causes in foals can include physiological stress, other bowel diseases including diarrhoea, prolonged time between feeding, infrequent nursing, use of NSAIDs, other illnesses e.g. pneumonia infections.


It is important to note horses can display no clinical signs yet have potentially severe gastric ulcers when confirmed by gastroscope3. Also clinical signs of stomach ulceration may be vague and can often be mistaken for other conditions or behavioural problems4.

Adult Horses:

  • Poor performance
  • Dull appearance
  • Picky appetite
  • Grumpy temperament
  • Resistance to riding aids
  • Resistance to girthing3



Foals can show clinical signs of ulcers from 2 days of age. Ulcers can often occur secondary to other diseases particularly bowel problems such as diarrhoea and obstructive colic.

Foals showing clinical signs will often have severe gastric lesions.

  • Salivation
  • Teeth grinding
  • Restlessness
  • Diarrhoea
  • Signs of colic including rolling
  • Poor appetite
  • Intermittent nursing

Types of Gastric ulcers

There are two types of gastric ulcers that can form, glandular mucosa and squamous mucosa, these occur in different parts of the stomach. Squamous mucosa ulcers are found in the proximal half of the stomach and 80% of ulcers occur in this region2. Squamous ulcers have a higher occurrence of ulcers due to the decreased physical barrier to acid as compared to that of the distal half of the stomach where the glandular mucosa is present, these accounts for only 20% of gastric ulcers.


If Equine gastric ulcers are considered the cause of symptoms, then the best diagnosis is to perform a gastroscopy. The vet will ask you to starve your horse overnight in preparation; this allows greater clarity when using the endoscope. On the day the vet will give sedation in order to perform the test, the test will last approximately 15-20 minutes. The gastroscopy involves the use of a 3 metre long endoscope being passed into the nose and then down the oesophagus into the stomach. This is often recorded in order for the horse owner to view easily. During the gastroscopy, the vet will score the stomach ulcers for severity. Gastric ulcer grading allows the vet to monitor healing and evaluate the efficacy of the treatment3. Once the gastroscopy is over, the vet will advise aftercare regarding food and water. Water can be given directly after the treatment, but food will need to be delayed in order for the horse to become fully alert from the sedation.

Gastric ulcer grades

Gastric ulcers can be graded on severity, the grades are from 0-4, and it is recommended that the best method for identification and grading of gastric ulcers is endoscopy, performed by a vet1.

If gastric ulcers are identified via gastroscopy in adult horses, treatment is available; the recommended treatment is oral treatment with medication over a period of weeks, depending on the severity of the EGUS. The vet will then monitor the treatment progress with regular visits and gastroscopy and also suggest management and feeding changes.

In foals, treatment is recommended from 4 weeks of age, depending on the clinical severity. Ensure you know the correct weight of your horse before dosing with oral treatment.

Ulcer Grading_ Gastric Ulcer


Management and Feeding changes

Rule 1: Feed horses little and often

Feeding little and often will allow the horse to buffer the continuous supply of acid produced in the stomach. By cutting down the high percentage of concentrates and replacing this with good-quality hay, alfalfa or grass will achieve this result4. Ensure at all times the horse has access to clean fresh water, as this is a simple step to reduce the risk of stomach ulcers. For horses in training altering the diet to provide enough nutrients to perform and prevent stomach ulcers can be done by consulting a nutritionist to design a programme to suit the horse’s needs and maximise potential.

Rule 2: Enable your horse to be in the field as much as possible each day.

Maintaining a horse in pasture can enable easier management of EGUS4. This will aid the overall wellbeing of your horse, reducing stress and allowing for natural grazing. Grazing will also help buffer the acid levels in the stomach.


Rule 3: Be prepared for physiological stress

Stress can be induced by shock, respiratory disease, injury and changes such as travelling, this can result in EGUS. In the event of such occurrence consult your vet so that preventative measures can be put into place.



  1. F., Bernard. W., Byars. D., et al Recommendations for the diagnosis and treatment of equine gastric ulcer syndrome (EGUS). The Equine Gastric Ulcer Council. Equine Vet ED 1999:11: 252-272.
  2. Andrews, F.M., Buchanan, B.R., Elliot, S.B., Clariday, N.A., and Edwards, L.H. 2005. Gastric ulcers in horses. Journal of animal science. 83 (E.Suppl.) E18-E21.
  3. Murray, M.J., Grodinsky, C., Anderson. C.W., Radue. P.E., et al Gastric ulcers in horses; a comparision of endoscope findings in horses with and without clinical signs. Equine Vet Journal. 1989:7 (suppl):68-72.
  4. Buchanan, B.R., and Andrews, F.M., 2003. Treatment and prevention of equine gastric ulcer syndrome. Vet Clinic Equine. 19, 575-597.


Kindly produced by Norbrook® manufactures of Peptizole®

Lizzie Barnard

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