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Gastric ulcer and Gastroscopy

Gastric ulcers: An introduction

Gastric ulcers in horses (also known as equine gastric ulcer syndrome or EGUS) are a common problem, particularly among racehorses and elite competition horses, although horse of all ages and types can have them, particularly if they have limited access to forage. Foals are also susceptible, not least because they have relatively thin gastric mucosa.

Squamous gastric ulcers occur when the digestive stomach acids come in to contact with the upper part of the stomach lining, which does not have the same protective layer as the lower part of the stomach. Glandular ulcers affect the bottom part of the stomach, which is submerged below the acidic gastric juices.

It can be hard to interpret the significance of gastric ulcers in the horse, as some horses will have no clinical signs, so it is important to review the whole horse health picture and not just the ulcers themselves.

Causes of gastric ulcers

In a natural environment the horse will graze for up to 16hrs a day, so acidity is reduced by forage passing through the stomach almost constantly, as well as by bicarbonate in the saliva that is produced as the horse chews.

If stabled horses have access to ad-lib hay, haylage or grass, this natural preventative process continues. But if they are fed high-concentrate diets with only limited access to forage, the acidity in the stomach increases.

Any prolonged period without forage intake, whether due to management practices or illness, leads to increased gastric acidity and a risk of ulcers.

Training which includes fast work, especially on an empty stomach, increases the risk of the acid splashing around, resulting in damage the upper part of the stomach.

Stress can also be a factor.

Research undertaken in the UK on the stomachs of slaughtered horses showed that even feral ponies living on the moors can develop gastric ulcers, although it was unclear whether they were living with them all the time or had developed them during the brief period between round-up and slaughter. The samples were all taken from animals slaughtered in mid-summer, when grazing was at its best and the predicted environmental stress at its lowest.

Diagnosing gastric ulcers in horses

There are no definitive external signs that a horse is suffering from gastric ulcers, but clues suggesting a performance 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).

Reasons for having a Gastroscopy procedure to check for gastric ulcers

Equine gastric ulcer syndrome (EGUS) is something we see increasingly frequently. Gastric Ulcers are common in horses and can effect horses of many types. The effect of gastric ulceration may be highly variable but they are believed to be associated with weight loss, changes in eating behaviour, change in character, poor performance and colic, although in many horses, they may cause few or no apparent ill-effects.

At the moment the only accurate and reliable way to diagnose gastric ulceration in horses is by gastroscopy (endoscopic examination). Gastroscopy allows examination of the stomach and any ulceration can be graded depending on how deep and how widespread the ulceration is and treated accordingly.

The procedure: Gastroscopy

Gastroscopy is performed under sedation and sometimes using a twitch. The gastroscope is a 3 meter long flexible fibre optic camera which is passed up one of the horse’s nostrils, the horse then swallows the gastroscope which is passed down into the stomach. Once inside the stomach, the stomach is inflated with air to allow full examination and the scope is manoeuvred to examine different regions of the stomach.

The procedure is usually well-tolerated by the horse and takes around 20 minutes. Horses are ready to travel home when the sedation has begun to wear off (usually after about 30 minutes).

Please note:



For horses inclined to eat their bedding, a muzzle should be placed. Both food and water can be made available to the horse as soon as the effects of the sedation have worn off.

Are there any side effects?

There are rarely any untoward side effects of gastroscopy, although occasionally a horse may show mild colic symptoms associated with distension of the stomach by air (this usually resolves one the air is withdrawn at the completion of the procedure).

Occasionally the gastroscopy procedure may result in a small nose bleed. This is perfectly harmless and will stop with in a relatively short time.

Treating gastric ulcers in horses

Gastric ulcers have been most commonly treated with an equine-specific form of omeprazole, given at a dose based on bodyweight. Other medications are now being use in some cases. How long the horse requires this will depend on how bad the ulcers are and the management of that horse and its diet.

Squamous lesions that are widespread and shallow typically heal faster (within 14-21 days) than more focal, deep lesions, which can take up to 28 days or even longer. Most cases respond well to treatment.

After this period gastric endoscopy can be repeated to check how the healing is progressing. If all is well treatment can move on to the maintenance stage to avoid the ulcers from reoccurring. If all treatment is stopped at this point there is some risk that the ulcers may reform (approximately 80% within six weeks).

For maintenance owners can continue using equine-specific omeprazole, but reduce the amount to a quarter dose. This is relatively effective in most cases and also user-friendly as it is a once-a-day treatment.

The alternative is to use an acid-neutralising feed supplement (containing aluminium hydroxide, magnesium hydroxide and calcium carbonate — think “Rennie” for your horse). This approach is less consistent and the supplement must be given three to four times daily, as its effect is short-lived. For glandular disease, another option is a coating agent supplement containing pectin and lecithin, given up to twice daily.

With a horse that has ulcers in the glandular area of the stomach, known as Equine Glandular Gastric Disease (EGGD), which is a different type of ulceration, will require different treatment. These glandular ulcers, affecting the bottom two-thirds of the stomach, will need additional treatment with the mucosal protectant sucralfate.

Also, a prostaglandin analogue is being used as an increasingly popular treatment. This has multiple mechanisms of action that may be of benefit, including suppressing acid production and inhibiting neutrophilic inflammation. Different treatment options should be discussed with your vet, depending on the precise type of ulceration affecting your horse, so please speak to the medical team at BELL EQUINE for the most up-to-date advice.

There are a variety of other supplements containing different fibrous material or proteins, seaweed, plant or mineral extracts; however, none of these have been proven to be clinically effective in either the treatment or prevention of squamous ulceration.

Preventing gastric ulcers

Any horse that has been diagnosed as having gastric ulcers, alongside horses that are high-risk of developing them, need their management reviewed in order to reduce the likelihood of the ulcers taking hold.

The following steps are recommended:

  • Allow access to high-quality forage, predominantly during the day (7am to 11pm), at a minimum daily rate of 1.5kg/100kg body weight (BWT). This should ideally be given continuously or at no more than 6hr intervals
  • Create multiple forage sources in the stable to improve eating consistency and allow foraging activity
  • Either hay (dry, soaked or steamed) or haylage can be used as the main forage source — there’s no difference between them in relation to ulceration
  • Feed no more than 0.25kg/100kgBWT of straw. This should not be the only forage source
  • Provide continuous access to fresh, clean water 24hrs a day
  • Split the concentrate ration into three rather than two meals per day
  • Opt for grains such as barley and oats instead of sweet feeds
  • Add chaff to all meals
  • Completely pelleted diets generate more stomach acid than the same diet formulated as a coarse mix
  • Buy high-quality feed, but bear in mind that there is no scientific evidence to support the use of specific “gastric healthy” commercial diets, nor of one manufacturer’s feed being better than another’s
  • Add a little corn oil or rapeseed oil (50-100ml per day) to help reduce the amount of stomach acid produced
  • Consider using fermented probiotics and the yeast Saccharomyces cervasii, which may increase the digestibility of the horse’s diet, so improving large intestinal function
  • Feed chaff before exercise — 2 litres chaff given within 30mins of exercise may trap acid and limit ulceration, and improve gastric blood supply. Use a 2-litre plastic drink bottle with the top cut off as a measure
  • Remember turn out at grass is beneficial for the majority of horses


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