Equine Gastric Ulcer Syndrome (EGUS)



It has long been recognized that horses kept in stables and in hard work can become grumpy, bad tempered, be difficult to girth up and sometimes go off their food. Indeed, when I first qualified over 30 years ago it was not unusual to describe these horses as just “having gone stale, or over the top” and a period of rest or less intensive work prescribed. Other symptoms that we now associate with ulcers range from teeth grinding, to reluctance to go forward when ridden, to colic.

With the advent of specialized gastro scopes for horses, we are now able to see inside the equine stomach and have discovered that ulcers are present in up to 90% of race horses in training, about 60-70 % of competition horses and surprisingly in about 30% of horses at grass, which might bring one to suggest that ulcers are almost normal! However, those horses at grass tend to have less severe lesions.


We all recognize that horses have evolved over many thousands of years to roam the plains, and studies on the Brumbies in Australia have seen these animals graze for about sixteen hours a day and travel on average 17 km on route. Wild horses usually move about at slow pace, only galloping when fleeing from danger. They rarely have a prolonged break from grazing and are likely therefore to have some food in their stomachs at all times.

Ulcers are most commonly formed when gastric acid, produced in the lower glandular part of the stomach and a vital part of the digestive system (as it acts to break down the food material at the start of digestion), comes into contact with the lining of the upper squamous part of the stomach for too long a period. As we have domesticated horses, we have altered their diet so that they have more energy for work, which inevitably means more hard feed (grains to provide carbohydrates) and less forage. We have changed their exercise patterns from a steady, day long amble to short periods of intensive activity and long periods of standing in a stable. When the horse is worked on an empty or near empty stomach the acid is splashed upwards and eventually will erode the stomach lining. Stress during periods of competition and travelling can cause reduction in appetite which can compound the problem, and stress itself can indirectly increase acid formation.



The only way to definitively diagnose ulcers is to gastro-scope them which allows direct vision of the lesions. Vets grade gastric ulcers from grade 1 which is slight discolouration to grade 4, a deep full thickness erosion.

There are no definitive external signs that a horse is suffering from gastric ulcers, but clues suggesting a horse may be suffering include:

  • decreased performance
  • attitude change (reluctance to work/not wanting to be tacked up)
  • poor body condition
  • reduced appetite
  • low-grade colic

To confirm that ulcers are present and what grade they are, a vet will use a video or fibreoptic endoscope to view the stomach lining of the horses (gastric endoscopy).


Fortunately, nowadays ulcers can be treated with omeprazole which along with a change of management usually results in recovery. However, recovery can take several months and omeprazole is very expensive. In addition, most vets will recommend regular gastroscopy to monitor the lesions which will add to the veterinary costs.  The majority of horses whose claims we are paying do indeed recover during the claim period, but what happens afterwards?

Omeprazole is recommended as a preventative measure but for many it would be impractical and for a lot of people too expensive for long term use.  The answer must surely be to look for easily implemented management changes that will help protect these horses in the future.


The aim must therefore be to try to feed as high a fiber diet as possible, avoiding carbohydrates as the principal source of calories, to feed a diet where energy is derived from oil and the fibre itself.  Daily turn out to allow free grazing is recommended and where this is not possible forage should always be available. Research has started to show that perhaps one of the “Golden Rules of Feeding” is in fact bad advice as it is not the best thing to allow one hour between feeding and exercise, it is preferable to let the horse have access to hay or even to give a small feed of chaff before tacking up for the competition!

Contributor: Annie Bevins MA Vet MB MRCVS, KBIS Equestrian Insurance.

KBIS British Equestrian Insurance is one of the largest independent horse insurance providers, providing all types of insurance for the equestrian including equine insurance, horsebox insurance, specialist bloodstock cover, personal accident cover, liability insurance for equestrian businesses and equestrian property insurance. kbis.co.uk


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