Could your horse have Equine Gastric Ulcer Syndrome?

By Wendy Talbot on 09 May 2017

It’s surprisingly common, but easy to miss. Equine Gastric Ulcer Syndrome (EGUS) can cause your horse serious pain and can also lead to weight loss and behavioural changes. The good news is that if you understand the condition, you can take steps to spot it and treat it or hopefully avoid it altogether.

What causes gastric ulcers in horses?

The causes of gastric ulceration in horses are based on many factors and are not completely understood. There are two main types of ‘ulceration’, those that occur in the top half of the stomach known as ‘Equine Squamous Gastric Disease’ (ESGD) and those in the bottom half, ‘Equine Glandular Gastric Disease’ (EGGD).  The two halves of the stomach have very different functions and the cause of ulceration is likely to be different in each.

Equine Squamous Gastric Disease

In ESGD, prolonged contact with gastric acid is the most important factor.  Horses have evolved to get their food by grazing and continually nibbling on grass, so their stomachs secrete gastric acid continuously, whether or not they’re actually eating. An adult horse can produce 1.5 litres of gastric acid in just an hour. The upper squamous part of the stomach is poorly protected against acid. If the horse continuously eats forage then a large proportion of acid is in effect soaked up, preventing damage to the stomach lining. However, modern horses are often kept on a different meal schedule. A horse that’s stabled and fed only at ‘mealtimes will rapidly develop an acidic stomach environment; it is this acid that causes ESGD.

Equine Glandular Gastric Disease

For EGGD the cause is less well understood.  The lower glandular part of the stomach actually produces the gastric acid and is designed to be continually in contact with it. Whilst some form of acid control is desirable in these cases, other factors which damage the usual protective mechanisms may be underlying causes of this type of disease, which may not be a true ulceration at all.

Whilst we do not know all the answers, some factors that can make EGUS worse are:

 Does my horse have gastric ulcer syndrome?

Unfortunately, the symptoms don’t make it immediately obvious. They may include behavioural changes (like not wanting to be saddled), poor performance, poor condition, weight loss and low appetite. Ulceration can also lead to colic, which can range from mild to acute, and can also be recurrent.

Of course, these could be symptoms of various conditions and some horses will show no signs at all. The only way to definitively diagnose equine gastric ulcer syndrome is for your vet to carry out a gastroscopy. This will involve looking at your horse’s gullet, stomach and upper intestine through a thin tube called an endoscope, for which your horse will need a standing sedation.

Is my horse at risk?

Different types of horse have different risk levels; up to 54% of leisure horses develop EGUS, and this rises to an astonishing 93% among race-horses in training. The high incidence of ulcers among race-horses is probably because they combine so many risk factors: stressful lives involving frequent travel, lots of exercise, little opportunity to graze and often a high-grain diet because of their increased caloric needs all likely contribute

Age is also a factor; up to 50% of foals may have gastric ulcers, although the causes and symptoms are often different from adult horses.

How do I avoid it?

Horses with a ‘natural’ feeding schedule are far less likely to develop equine gastric ulcer syndrome. Free access to pasture for grazing is ideal, but long periods of grazing are also good. If you have to keep your horse stabled for long periods make sure there is always access to hay. It’s also important for your horse to have access to clean water at all times.

Taking steps to minimise stress to your horse will help too. Are there things you can do to keep your horse calmer? Reducing disruption to its environment? Establishing a more settled routine?

How do I treat it?

Once you have a diagnosis of equine gastric ulcer syndrome from your vet, it can often be treated very effectively with orally administered medication. This will work by reducing the amount of acid your horse’s stomach makes. Your vet will advise you on the best treatment for your horse and subsequent management.

Find out more about EGUS here.

References and further reading

Sykes BW, et al. European College of Equine Internal Medicine Consensus Statement—Equine Gastric Ulcer Syndrome in Adult Horses. J Vet Intern Med 2015;29:1288–1299



Wendy graduated from Bristol University in 1999. She then went on to complete a residency at Liverpool University and holds a European Diploma in Equine Internal Medicine. After working in practice for 13 years, she joined Zoetis in 2012 as the National Equine Veterinary Manager.

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