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Equine Gastric Ulceration Syndrome (EGUS)


Does your horse suffer from any of the following?

  • Poor appetite or weight loss
  • Poor body condition or hair coat
  • Recurrent colic
  • Poor performance
  • Behavioural changes “grumpiness”
  • Discomfort on girth tightening
  • Crib biting (possible link)


Did you know that gastric ulcers can affect leisure and performance horses as well as racehorses?

Studies show that between 90% and 100% of racehorses in training have gastric ulcers but perhaps the most shocking prevalence is in the performance / sport horses where up to 75% have been shown to be affected by gastric ulcers.

Approximately 35% of non-performance / leisure horses have also been found to have gastric ulcers. There is thought to be a slightly higher prevalence in geldings and it seems that the risk increases with the age of the horse.


Gastric ulcers form where there is increased exposure to acid or when the protective mucous lining of the stomach fails.

Feeding regime plays a huge part, both in the substances being fed and also how and when it is fed. There is an increased risk with a grain dense or pelleted diet where we see more carbohydrate fermentation which produces volatile fatty acids which can worsen acid injury and lead to ulcer formation. In management regimes that involve the feeding of oral electrolyte solutions ulcers are more common and more severe.

Exercise regimes are also implicated. When horses perform faster than a walk there is a reduced stomach size due to an increased abdominal pressure which can mean any acid becomes more concentrated.
Stressful situations or experiences such as transport or stabling can rapidly cause ulcers to develop.


The only proven reliable means of diagnosis of EGUS is by looking directly at the stomach lining by means of a 3m endoscope. Some test kits measuring faecal occult blood are available but have been shown to be of limited value.

EGUS is believed to be greatly under-diagnosed because of the assumption that the condition only affects racehorses and also because of the wide and sometimes vague range of signs shown outwardly by the horse. It is only recently that the wide prevalence and consequences of EGUS are being fully recognised and there are only a limited number of veterinary practices that own a 3m endoscope.

Horses undergoing endoscopy need to have food withheld for approximately 12hrs before the procedure. Passing of the endoscope is done under sedation and is well tolerated. Ulcerated areas are graded out of 4 in severity with grade 2 and above being considered to be causing significant clinical signs in adult horses.


Feeding regimes are key in prevention of EGUS. Plentiful roughage is vital as it is the production of alkaline saliva produced in greatest amounts when a horse eats fibrous foodstuffs that provides a continues natural defense against excess stomach acid. Ideally multiple forage types and multiple sources (i.e. 2 or 3 haynets) are provided as this maximises salivation. Hay or haylage, alfalfa or chopped straw can be used.

As well as increasing forage it is important to reduce the amount of carbohydrate fed, if greater calorie density is needed then corn oil or hemp oil added to the fed provides an alternate energy source and have been shown to promote ulcer healing.

Gastric ulcers are seen much less frequently in horses living at pasture with other horses. Allowing freedom to express normal equine behaviour within a stable herd minimises the stress of any exercise or management regime.

Also useful in prevention in at risk horses are acid production inhibitors such as Gastroguard at ¼-½ the treatment dose after an intensive exercise period or at the start of training.


The treatment aims are to decrease acid production and limit further damage to allow healing of the stomach lining.
The only licenced drug for treatment of EGUS is GASTROGUARD which contains omeprazole, this has proved to be by far the most reliable treatment method and is given in a once daily dosing syringe.

Stringer Equine believes that some supplements can be extremely beneficial to those at risk horses such as Pronutrin and Succeed (get in touch for details).

Other treatments can be used but the effects are short lived and must be given 4-6 times daily. The most commonly used alternative treatment for EGUS is called Neighlox which can reduce acid levels enough to reduce signs shown by the horse but not to a level that allows healing.

The practice has a video endoscope which allows owners to see what the vet is seeing and is fully portable so horses undergoing the procedure will not have to travel.

If you are concerned that your horse may be suffering from any of the above symptoms, or for advice on management and feeding, please feel free to contact us.

Richard Stringer BVSc MRCVS of Stringer Equine Veterinary Practice