Gastric Ulcers in horses

Gastric Ulcers in horses

Gastric Ulcers (also known as Equine Gastric Ulcer Syndrome or, EGUS) is a common condition in horses of all ages, breeds and lifestyles. They develop when stomach acid builds up and irritates the lining of a horse’s stomach, causing ulcers to form. Gastric ulcers are painful and if left untreated can cause the stomach lining to burst, which can be fatal.

Regular intense exercise and a performance diet can cause or aggravate gastric ulcers, and for this reason they are very common in thoroughbred racehorses and sport horses. However, they are also reasonably common in leisure horses, and around 50% of all foals will develop ulcers.

What are Gastric Ulcers?

There are two main types of gastric ulcers; squamous ulcers (the most common kind) and glandular ulcers (less common). The severity of both kinds can range from mild irritation of the stomach lining to the potentially fatal perforation of the stomach lining.

Squamous ulcers

Squamous ulcers occur in the top third of the stomach, an area which doesn’t usually come into contact with stomach acid. When aggravating factors such as diet, stress or exercise cause a build-up of stomach acid, it can splash onto this sensitive tissue at the top of the stomach, causing ulceration. 

These ulcers develop quickly and can often be identified by monitoring changes in your horse's behaviour. Reduced appetite and symptoms of colic can indicate squamous ulcers, but it is possible for your horse to display no symptoms at all.

Glandular ulcers

Glandular ulcers are less common in horses but can be more serious and harder to spot as they don't always cause symptoms. These ulcers grow slowly and occur in the bottom two thirds of the stomach which produces gastric acid. They develop when the natural mucus protecting the stomach lining fails, although exactly what causes this failure is unknown and seems to vary case by case. 

What are the signs and symptoms of gastric ulcers in horses?

Horse scratching

Horses with gastric ulcers will not always exhibit symptoms, and the symptoms displayed may not always indicate gastric ulcers. The only way to accurately diagnose gastric ulcers is with a gastroscopy, a procedure where a camera on a tube is lowered into your horses’ stomach to allow your vet to view the lining.


Signs which may indicate gastric ulcers include:

  • Loss of appetite or slow eating
  • Weight loss
  • Low energy or poor performance, which can show itself in shorter strides or lower jumps in racing and sports horses
  • Discomfort when the girth is tightened
  • Change of attitude or mood, this could be a reluctance to be ridden or a generally agitated manner
  • Dull coat
  • Crib biting
  • Symptoms of colic such as rolling, pawing at their stomach or grinding teeth
  • Diarrhoea (foals only)

What Causes Gastric Ulcers in Horses?

Horses in the wild tend to live quite a sedentary lifestyle, grazing in fields and meadows for up to 16 hours a day. Their digestive systems have evolved to suit this lifestyle, and are not always well equipped for the life of a modern horse. 

Factors which are known to cause, or increase the risk of, squamous gastric ulcers in horses include:
Regular intense exercise (racehorses and performance horses are more at risk)
Erratic feeding and limited access to forage
A performance, concentrated diet
Stress, isolation and travelling (one explanation for the high occurrence of gastric ulcers in foals is due to the stress of moving homes when they are being bought and sold)
Intermittent access to water

Each of these factors can cause excess stomach acid. In nature this would be neutralised by the saliva created when chewing grass and hay, and by the forage itself passing through the digestive system. For this reason, increasing free access to forage and constant access to water is a key way in which you can help to prevent gastric ulcers in your horse.

If your horse is travelling frequently to competitions, ask your vet about other preventative measures that can be used. 

It is not known exactly what causes the less common glandular ulcers, but it is believed that they occur when the mucus at the bottom of the stomach is damaged or changed by trauma, toxic foods, or bacteria.

How are Gastric Ulcers in Horses Treated?

Once a vet has diagnosed gastric ulcers via a gastroscopy, they will usually recommend a mixture of medication and lifestyle changes. 

The most commonly prescribed medication for both types of gastric ulcers is Gastroguard, a proton pump inhibitor. Proton pump inhibitors are medications which have a long term impact on reducing production of stomach acid, like a powerful antacid for your horse. 

Your vet is likely to recommend continual access to grass or hay, 24 hour access to fresh water and more frequent feeding of low concentrate food. Whilst your horse may be able to come off medication after a few weeks or months (depending on the severity of the ulcers), you will need to commit to these lifestyle changes for the long term. 

It is likely your vet will need a second gastroscopy before changing or reducing any medication, but it is not painful or traumatic for the horse.

It's always worth buying some sort of health insurance for your horse to give you the peace of mind that you won't have to make a decision about vet care based on cost. Take a look at your options and protect you and your four-legged friend.