A look at Equine Gastric Ulcer Syndrome (EGUS)

It seems that many horses today are affected by gastric ulcers (ulcers in the stomach). However, it’s only really in the past 20 years that long endoscopes have become common in equine veterinary practice and the true prevalence of equine gastric ulcer syndrome has become apparent. It’s almost certain that horses had gastric ulcers before we started looking, but things like unexplained weight loss, poor condition and abnormal feeding behaviour were likely attributed to other issues.


Equine Gastric Ulcer Syndrome (EGUS)

The preferred term currently is Equine Gastric Ulcer Syndrome (a syndrome is a group of symptoms which consistently occur together, or a condition characterised by a set of associated symptoms as distinct from a disease which is characterised by specific symptoms). EGUS comprises two diseases – Equine Glandular Gastric Disease (EGGD) and Equine Squamous Gastric Disease (ESGD). These refer to the regions where the ulcers occur. EGGD refers to ulcers in the glandular, acid-secreting lower part of the stomach, whilst ESGD refers to ulcers in the upper (non-acid secreting) part of the stomach (covered by a type of tissue referred to as squamous epithelium).

ESGD is believed to occur primarily due to management associated with stabling, training, travelling and competing (as opposed to horses kept in low stress extensive management). ESGD in exercising horses has been suggested to be due to acid splashing up from the lower part of the stomach (hence the recommendation to feed forage prior to exercise to reduce the splashing). EGGD appears to primarily occur due to delayed gastric emptying caused by other disease processes. Thus, ESGD and EGGD can often occur together but may have different underlying causes.


How common is EGUS?

EGUS has generally been found to be lowest in pleasure horses and highest in Thoroughbred and Standardbred racehorses in training. However, occurrences of over 60% have been found in some studies of showing horses, endurance horses and eventers.


What factors appear to increase the risk of horses having EGUS?

Most studies have not found any clear association of risk of EGUS with age or sex. It may be that certain breeds, such as Thoroughbreds, are more predisposed to EGUS.

Factors that appear to significantly increase the risk (risk factors) of horses developing EGUS include:

  • High stress environments.
  • Living in an urban area.
  • Lack of direct contact with other horses.
  • Lack or minimal pasture turnout.
  • Forage restriction.
  • Straw feeding.
  • Low fibre intake.
  • Feeding sharp forage e.g. Chaff that has been chopped to leave sharp ends.
  • Large meal size.
  • High starch content.
  • Long intervals between meals.
  • Few meals (e.g. Two per day).
  • Intermittent access to water.
  • Hard or prolonged exercise.

What are the signs suggested to be linked to the gastric ulcers?

Signs that have been suggested as likely to indicate gastric ulcers (a combination of signs suggested from controlled studies, clinical experience and popular culture):

  • Change in appetite
  • Being fussy about new foods
  • Change in behaviour
  • Change in behaviour at feeding time
  • Weight loss
  • Poor coat condition
  • Loss of performance
  • Colic
  • Signs of abdominal discomfort
  • Crib biting
  • Rearing
  • Bucking
  • Back pain
  • Diarrhoea/loose droppings
  • Grinding teeth
  • Resenting saddle
  • Resenting girthing
  • Not going forward

Of these, the more reliable signs that point to EGUS include:

  • Colic – Some studies indicate an increased risk of colic in horses with gastric ulcers. In one study over 80% of horses with repeated episodes of colic had gastric ulcers.
  • Poor appetite and loss of condition – At least three studies have suggested poor appetite or being a ‘fussy feeder’ is associated with an increased likelihood of gastric ulcers. In racehorses, poor body condition appears to indicate a high chance of gastric ulcers being present.
  • Behaviour – Horses showing stereotypical behaviour such as box-walking, wind-sucking and crib-biting, or a change in behaviour were found to be more likely to have ulcers in two separate studies. Anxious horses in one study were more likely to have ulcers.
  • Loose droppings – Very lose droppings (diarrhoea) was reported to be associated with an increased risk of gastric ulcers in one study. However, this has not been supported by other studies. Stress can lead to loose droppings and gastric ulcers, but it appears at this time that loose droppings and gastric ulcers are not directly connected.
  • Loss of performance – Whilst believed to be an important effect of gastric ulcers amongst horse owners and racehorse trainers, only a few studies have examined this aspect. The best evidence for a negative effect of gastric ulcers on performance comes from a study where horses were treated for gastric ulcers.

The use of clinical signs to diagnose gastric ulcers is best summed up by this consensus statement of the European College of Equine Internal Medicine (ECEIM):

“Although a wide variety of clinical signs might be present in individual cases of EGUS, they are nonspecific and are poorly associated with the presence of EGUS. The committee therefore does not support the practice of diagnosing EGUS based on ‘characteristic’ clinical signs and recommends that EGUS be confirmed by performing gastroscopy…”

European College of Equine Internal Medicine Consensus Statement—Equine Gastric Ulcer Syndrome in Adult Horses. B.W. Sykes, M. Hewetson, R.J. Hepburn, N. Luthersson, and Y. Tamzali (2015).

However, that said, the risk factors your horse has from the list above and the more clinical signs, especially colic, reduced appetite and or loss of condition and altered behaviour (especially around feeding), then it would be reasonable to consider that gastric ulcers may be present.


Diagnosis of EGUS

A definite diagnosis of EGUS can only be made by gastroscopy; passing an endoscope – a tube with a camera on the end up the nostril and down the oesophagus into the stomach. However, due to cost or other reasons, it has not been uncommon for horses suspected of having gastric ulcers to be treated with medications or gastric ulcer supplements. In these cases, a significant improvement following treatment would suggest that ulcers had been or are present.


What to do if you think your horse may have EGUS

If your horse has many of the risk factors for EGUS and is showing a number of the clinical signs, your first step should be to consult your vet and discuss whether gastroscopy is indicated or not.

You can find out more about – Treating and managing EGUS here.


by Dr David Marlin, Pure Feed Nutritional Consultant

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