Dr Kirstie Pickles BVMS MSc PhD CertEM(IntMed) DipECEIM MRCVS

Over the following weeks we will be looking in detail at stomach ulcers in the horse. Briefly, horses can get two different types of stomach ulcers which are defined by whether they occur in the squamous or glandular mucosa (see the image below). Equine gastric ulcer syndrome (EGUS) is a general term describing equine stomach ulcer disease. This week we focus on the anatomy of the stomach, clinical signs and diagnosis of EGUS.


Figure 1: Endoscopic view of the inside of a horse’s stomach showing the non-glandular (squamous) and glandular areas of the stomach. The yellow arrows point to the margo plicatus, the area where these two regions meet.

The stomach of the horse is small, holding only 8-12 L depending on the size of the horse. The inside of the stomach is covered by two different types of lining, squamous (non-glandular) and glandular (figure 1). The squamous lining covers the top half of the stomach and is an extension of the lining of the oesophagus. The glandular mucosa covers the bottom half of the stomach and contains cells that produce stomach acid and enzymes. To protect the glandular lining from this acid, these cells are covered by a thick layer of mucus. There is no mucus layer over the squamous lining. The area where these two linings meet is called the margo plicatus.

Clinical Signs

It is impossible to tell from clinical signs alone if a horse has EGUS. Some horses make it very obvious that there is a problem however others can have terrible ulcers and show no clinical signs at all. Signs that have been documented in horses with EGUS are:

  • Change in eating habits
  • Slower to eat meals
  • Picky eating or leaving feed
  • Pawing, ears back, grunting, leaving and coming back to the bowl during the meal
  • Change in behaviour
  • Aggression
  • Spooking
  • Unsettled or on high alert
  • Sensitivity to touch
  • Reactive when being rugged / girthed / groomed
  • Teeth grinding
  • Changes under saddle
  • Being disunited in canter
  • Kicking out or biting round to side with leg aids
  • Not going forward
  • Being spooky or irrational
  • Poor / reduced performance
  • Changes in appearance
  • Loss of top line
  • Loss of condition or weight loss
  • Dull coat
  • Changes to health
  • Recurrent colic
  • Loose droppings


Even when it seems there is no doubt that a horse has gastric ulcers, gastroscopy (viewing the inside of the stomach with a camera) should always be performed. Although the signs listed above are highly suggestive of gastric ulcers, they are not diagnostic or exclusive to gastric ulcers. Not only is it expensive to “trial and treat” a horse which does not have ulcers, it is also not beneficial for the horse’s general health.

Performing gastroscopy is important for more reasons than a diagnosis. We now understand that there are two types of ulcer disease seen in the stomach (see part 2), and the causes, treatment and response to treatment of these differ. It is therefore essential that the horse is scoped to determine which type of ulcer disease (if any) the horse has.

Owners are often hesitant about having their horse gastroscoped, most commonly because horses need to be starved for 12-16 hours before the procedure to ensure that the stomach is empty of food to allow any ulcers to be seen. This is an understandable concern; however, horses usually deal with this period of fasting very well. Starving is usually performed overnight when the horse will naturally stop eating for 4-6 hours. The benefits of properly understanding the nature of the problem vastly outweigh any stress caused by a starvation period. The procedure itself is performed under light sedation and is tolerated extremely well.

Next week: Equine squamous gastric disease

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