Video from the equine team at Towcester Veterinary Clinic using a gastroscopy to examine the stomach of a horse suffering from gastric ulcers.

Around three-quarters of sport horses are thought to be affected by gastric ulcers or equine gastric ulceration syndrome (EGUS), according to Richard Hepburn MRCVS.

Totals vary in different disciplines, with roughly 80-100% of racehorses in training suffering, falling to around half of the racehorses out of training. Around 80% of eventers and dressage horses, 60% of endurance horses and 40-45% of Western riding horses are estimated to have EGUS.

“The high prevalence of gastric ulceration did prompt the question ‘are ulcers normal?’” says Richard. “However, an American study published in the Journal of Equine Veterinary Science #26, using college-owned horses with lifestyles not dissimilar to horses in the wild, found that only 10% had any ulceration.”

The connection between EGUS and the competition horse lies in management. The lifestyle of the average sport horse includes periods of feed deprivation; a low-fibre, high-carbohydrate diet; and restricted grazing, all of which can quickly lead to gastric ulceration.

“This is a problem that has arisen in the modern sport horse out of our own doing,” Richard states.

However, while many horses have gastric ulcers, not all show clinical signs, and some disciplines seem more affected than others.

“Flat racers and polo ponies seem to cope with gastric ulceration better — possibly because they do short bursts of exercise,” Richard explains. “In contrast, dressage and event horses, who have to concentrate for longer, can have mild ulceration but show considerable symptoms.”

Possible causes of gastric ulcers in horses

  • Some drugs, like bute, which can lessen the stomach’s defences against acid
  • Stress from transport or competing, which may lead to an increase in stomach acid production
  • Fast exercise during which the stomach shrinks while production of stomach acid increases, and splash ulcers can occur

Signs of gastric ulcers in horses

  • Rough hair coat
  • Poor appetite
  • Weight loss
  • Slow eating
  • Pain during girth tightening
  • Poor performance
  • Behavioural changes
  • Colic

This information was first published in Horse & Hound (14 August 2008)