Stomach Ulcers

There are many clinical signs associated with stomach ulcers:-

Weight loss

Poor/stary coat


Pain on tightening the girth

Behavioural changes.

The prevalence of stomach ulcers in horses can be as high as 90%, particularly in racehorses. However, even in pleasure horses it can be over 50% and this rises to 70-80% in competition horses.

Irregular or intermittent feeding or diets high in carbohydrates (sugars) are recognised as causes of stomach ulcers. However, other causes commonly include periods of stress and exercise such as competition, training and transport. However, management and dietary changes that occur with box rest or illness can exacerbate ulceration.

Horses have a stomach that is divided into two areas, the squamous and glandular parts that are separated by a distinctive line called the Margo Plicatus. These areas have a different lining that determines how the ulcers are formed.

There are two distinct types of stomach ulcers that are regarded in the consensus on Equine Gastric Ulcers as two separate conditions:-

  1. Equine Squamous Gastric Ulcer Syndrome (ESGUS). This is the horse equivalent of acid reflux in humans. ESGUS occurs because the squamous (white) lining does not have a mucus layer to protect it from the acid produced in the stomach (the mucus and acid are produced by the glandular lining). The splashes of acid come into contact with the lining and erode the surface to varying extents to produce ulcers grade 0-4 (0 is normal, 4 is the most severe).

The treatment is a drug called omeprazole (Gastrogard) and is very effective. Commonly a higher dose is given initially for approximately one month and then a reduced dose may be given.

In addition management of ESGUS is vital in longer term control of ulcers. This involves giving the omeprazole on an empty stomach before then waiting 20-30 minutes before feeding. Also the feed should contain high levels of fibre and oil. Buffering of the stomach acid can be helped with feed or supplements that contain pectins (sugar beet), lecithins and antacids.

Feeding fibre approximately 30-60 minutes before exercise can also produce a protective “mat” over the acid in the stomach and so reduce the splashing effect.

Grazing in the field does not prevent ulcers completely but as horses spend up to 18 hours a day eating there is a constant input of small amounts of fibre.

  1. Equine Glandular Gastric Ulceration Syndrome (EGGUS). This is the similar to human gastric ulcers. It occurs in the glandular (pink) part of the stomach, in particular, around the pylorus (outflow from the stomach to the small intestine).

In humans this has been associated with bacterial infections such as Helicobacter species but in horses, although bacterial infections are thought to contribute to the glandular ulcers, Helicobacter has not been isolated. These can also be graded 0-4 although there does not appear to be a correlation between severity of ulcers and severity of clinical signs.

Treatment of EGGUS is generally more difficult than ESGUS but commonly involves the use of Sucralfate which produces a thick gel which increases the mucus protection. Antibiotics such as Doxycycline are also used especially when a bacterial infection is suspected. Management/prevention again involves the use of the pectins, lecithin and antacids as well as grazing and dietary management.


The only way to accurately diagnose the presence of stomach ulcers is by a 3m long gastroscope. This allows fantastic visualisation of the lining of the stomach and distinction between ESGUS and EGGUS; this provides a more accurate, targeted treatment.

The use of faecal blood detectors has not been proven to be accurate in the presence of ulcers and cannot establish the grade/severity.

Occasionally we investigate “choke” (when food becomes stuck in the oesophagus or food pipe) using gastroscopy to visualise the cause. It may be that there are larger pieces of food such as carrot or apples that are causing the obstruction and these can be moved using the ‘scope.

Gastroscopy also allows biopsies to be taken in very rare cases of tumours of the stomach or upper small intestine.

Stomach impactions are also very unusual but are also easily seen using the gastroscope.