Gastric Ulcers

Gastric ulcers or Equine Gastric Ulceration Syndrome (EGUS) was once considered a problem that only affected racehorses, but it is now recognised as becoming increasingly common in sport and leisure horses, with as many as 50% of horses in work affected by the condition.

Gastric ulcers are an erosion of an area of the stomach lining as a result of contact with gastric acid. A horse’s stomach is divided into two distinct parts; the bottom two-thirds is known as the glandular region. Here the stomach lining continuously produces gastric acid as part of the digestive process, but at the same time also secretes mucous which acts as a protective barrier, preventing damage to the lining from the caustic effects of the acid. The upper portion of the stomach is non-glandular and does not have a protective lining. Here ulcers can occur when acid ‘splashes’ up from the glandular region often as a result of there being insufficient fibre in the stomach to soak up the acid.

Gastric ulcers are more common in the upper part of the stomach where the lack of protective lining makes the area more susceptible to erosion by gastric acid, however, ulcers can occur in the lower portion of the stomach as a result of a failure of the protective mucosa.

Saliva contains sodium bicarbonate which is the horse’s natural buffering agent against gastric acid in the upper, non-glandular part of the stomach. Unlike humans, who produce saliva continuously, horses only salivate when they are actively chewing. Fibrous feedstuffs such as hay, haylage, grass and chaff all require more chewing than concentrated feeds which is why it is important that horses have a continual supply of fibre.

In the wild, horses will spend the majority of their time grazing and have evolved as trickle feeders with a digestive system that is designed for a continuous supply of high fibre feed. Fibrous feeds, such as grass, hay and haylage are bulky and as such will fill a horse’s stomach and act as a sponge, soaking up the acid. Modern management systems mean that many horses, especially performance horses, may spend a large proportion of their time stabled and are often fed diets that are high in starch and low in fibre. This means they may spend considerable time with empty stomachs.

Stress too can increase the likelihood of gastric ulcers developing. Horses that are stressed or in intense training programmes may have increased levels of corticosteroids which reduces blood flow to the stomach lining and can make it more susceptible to damage from the gastric acid.


Signs that may indicate a horse is suffering from EGUS can vary significantly between horses and unfortunately there is no definitive set of symptoms on which to base a diagnosis; however the following may indicate EGUS and further veterinary investigation is recommended:

  • Sensitivity when girthing or grooming the abdomen
  • Loss of appetite
  • Loss of weight and/or body condition
  • Poor coat condition
  • Change in temperament, i.e. becoming grumpy or irritable
  • Reduced performance or reluctance to work
  • Low grade, recurrent colic


Currently the only way to diagnose EGUS is through gastroscopy, which involves passing a tiny camera all the way down the oesophagus into the horse’s stomach. This usually requires the horse to be sedated and to have been fasted for at least 8 hours (preferably 16 hours) to ensure the stomach is empty and the lining clearly visible.

The severity of EGUS is graded on a number scale of 0-4, with 0 indicating a normal, healthy stomach lining and 4 being severe ulcers where there is a greater proportion of ulcerated tissue than normal stomach lining


Foals can be more prone to gastric ulcers than adult horses due to their developing stomach lining being comparatively thinner. Ensuring newborn foals receive adequate colostrum will aid the development of the stomach mucosa. Foals also may not be eating sufficient fibre to produce enough saliva to buffer the effects of the gastric acid, so introducing them to grass and hay as early as possible will ensure they are eating plenty of fibre at weaning to help minimise their risk of gastric ulcers developing. Avoiding stressful situations such as rough handling, unnecessary transportation and early weaning will also all help to prevent digestive distress.

Treatment and prevention

Depending on the severity of the ulcers, treatment can simply involve a reduction in workload for horses that are in hard work, together with management changes to give the horse a more natural lifestyle, e.g. 24-hour turnout and access to ad lib forage when previously this may have been restricted. Dietary changes to reduce the starch content of a horse’s diet can also be effective, e.g. changing from a cereal-based course mix to a high fibre, cereal grain free feed is highly recommended. In cases where the ulcers are severe, the daily administration of drugs known as proton pump inhibitors which suppress acid production, are often prescribed.

The implementation of long-term management changes is vital to minimise the risk of the ulcers reoccurring.

Daily turnout and ad lib forage

Mimicking the horse’s natural lifestyle as much as possible is particularly important. Providing 24-hour turnout is ideal and the majority of horse and ponies can be worked and competed successfully whilst living out. If constant turnout is not possible, maximising the amount of time your horse spends in the field should be a priority. Any extra grazing time your horse has can have a positive effect on digestive health. Providing ad lib forage when stabled and out in the field when grazing is poor will ensure that the horse always has fibre available to eat. The chewing of this fibre will promote saliva production and aid the horse’s ability to buffer the effects of the gastric acid.

Forage should also be available to the horse when travelling and in other potentially stressful situations, such as shoeing and clipping.

Feed fibre before exercise

One of the age-old golden rules of feeding horses is not to exercise on a full stomach, however, this only applies to concentrate feeds and it is actually highly recommended to allow your horse some hay or chaff immediately before exercise. Having fibre present in the stomach will help to prevent the gastric acid splashing up into the non-glandular portion of the stomach, where ulcers are most common.

Feed a low starch, high fibre concentrate feed

Forage in the form of grass, hay and haylage should form the majority of a horse’s diet. If additional concentrate feed is required, either to provide energy for work or to maintain body condition, this should be one which is high in fibre and low in starch. Feeds containing cereals should be avoided and instead, those which use fibre and oil as energy sources are much lower in starch and more natural for the horse. Any concentrate feed should be split into as many smaller meals as possible. Unless the horse is overweight, the addition of oil to the diet is beneficial as this can reduce acid production.

Adding chaff

Adding chaff to a horse’s feed will further increase the fibre content of the diet and also extends feeding time. This, in turn, encourages the horse to chew for longer and increases saliva production. Any unmolassed chaff is suitable to be fed, however, an alfalfa chaff is often recommended for horses with EGUS. Alfalfa is naturally high in protein and calcium which is thought to help neutralise the stomach acid and thus lessen the risk of ulcers developing.

Minimise stress

Reducing a horse’s stress levels will help prevent EGUS developing or re-occurring and so it is important to know your individual horse’s likes and dislikes. Allowing a horse the company of others whilst ensuring he isn’t being bullied by a dominant companion is important, as is keeping to a strict routine if he is the type of horse to become stressed by sudden changes in his environment or lifestyle.

Barley & Molasses Free Range

When fed in conjunction with ad lib forage, our Barley & Molasses Free Range offers a higher fibre, lower starch alternative to traditional cereal-based feeds.