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How to Keep Your Horse’s Stomach Healthy and Ulcer-Free

Gastric Ulcers1Within the past decade, researchers and vets have realised the worryingly high prevalence of stomach (gastric) ulcers in all types of horses, especially in performance horses. Between 40 and 90% of performance horses have gastric ulcers. Less data has been gathered from leisure horses, but up to 50% may be affected. The term Equine Gastric Ulcer Syndrome (EGUS) is used to describe ulcers in the stomach, the end of the oesophagus (where it meets the stomach) and the top of the duodenum (the first part of the small intestine).

Gastric ulcers cause pain and discomfort, and can be associated with a poor appetite, weight loss, chronic low-grade colic, behaviour changes and poor performance.

Stomach challenges

It’s not surprising that our domesticated horses suffer so often from gastric ulcers. Their management has changed so much from how they evolved, with confinement, meal feeding, low-forage, concentrate-rich diets, long periods of fasting, early weaning and intensive exercise programs commonplace. All of these factors contribute to a higher risk of gastric ulcers due to encouraging an acidic stomach with poor buffering.

Swallowing of saliva produced during chewing plays an important role in buffering normal gastric acid, so encouraging a horse to chew by feeding plenty of forage is a key factor in preventing ulcers. Unlike humans, horses produce gastric acid whether or not there is any food or saliva entering the stomach, so periods of fasting can cause excessive acid build up, a very low stomach environment pH and acid exposure to the unprotected, upper, non-glandular area of the stomach.

Ulcers can be found in both the glandular and non-glandular area, the border of the non-glandular and glandular area, and the oesophagus where it enters the stomach, as well as the duodenum where it leaves the stomach. Most ulcers are found in the non-glandular region where it meets the glandular region.

The most severe ulcers tend to be found in horses in hard training, and an increase in severity and/or number of lesions has been reported in Thoroughbred racehorses compared to other performance horses. Workload seems to be an important risk factor, possibly due to abdominal pressure causing stomach contraction during cantering and galloping, which causes acid splashing of the upper, unprotected, non-glandular part of the stomach.

Ulcers in the non-glandular region of the stomach tend to be caused by excess gastric acid, and also acid splashing from fast exercise, since this area lacks protection from mucus. Ulcers in the glandular area tend to be caused by a problem with the mucosal protective factors rather than acid injury, which can be caused by excessive use of non-steroidal anti-inflammatory drugs (NSAIDs). There may be bacterial infection involved in glandular ulcers.

The severity of symptoms are not necessarily closely associated with the severity of ulcers, therefore they may be a poor indicator. Some horses can have severe ulcers with no symptoms, whereas others can have few, mild lesions but show marked symptoms.

Symptoms associated with gastric ulcers may include:

  • Poor appetite, or loss of interest in either forage or concentrate
  • Poor hair coat
  • Weight loss
  • Behaviour changes – can involve increased fear/flight or dullness
  • Abdominal discomfort, especially discomfort on girth tightening
  • Chronic colic
  • Poor performance

If you suspect gastric ulcers, contact your vet without delay. Apart from being associated with poor performance, untreated ulcers are a welfare issue, and can eventually lead to stomach perforation and peritonitis, and potentially death.


Horses at grass have a lower risk of gastric ulcers, probably due to the intake of fibrous forage and saliva, and resultant less acidic stomach environments. Thoroughbred race horses allowed turnout were less likely to have ulcers. Social contact seems to help reduce the risk of ulcers also, and in addition improves the welfare of the horse. Minimising stress seems to reduce the risk. Prompt veterinary intervention is required should a problem be suspected, and treatment with the proton pump inhibitor omeprazole is usually very effective.

In conclusion, management factors that reduce the risk of gastric ulcers include:

  • As much turnout as possible – for the benefits of grass and the ability to move about
  • Social contact
  • Low stress lifestyle
  • Careful (minimal necessary) use of NSAIDs
  • Prompt veterinary intervention when a problem is suspected


Careful feeding can have a huge impact on the health of ulcer-prone horses and ponies. The most important factors are to allow – if possible – free access (ad lib) forage, which means that care should be taken in finding appropriate forage for the horse, and limited dietary starch. As much pasture turnout as possible i.e. free access to grass should be given, with care taken that the horse doesn’t put on an unhealthy amount of weight.

Forage promotes chewing, which helps buffer stomach acid, as well as providing the stomach with a mat of fibrous food that helps stop acid splashing onto unprotected non-glandular areas. Choosing good nutritional quality forage for hard-working horses is important because this reduces the reliance on concentrate feed, which – if starchy – increases the risk of ulcers.

Offering several different types of forage to stabled horses can increase the amount they eat, and this could reduce the risk of ulcers. In practice, hay, haylage and a large bucket of alfalfa chaff could be fed to a stabled horse.

Ensure there is some forage in the stomach before fast work, to try and minimise acid splashing onto unprotected areas. Feeding a small meal of alfalfa, which is rich in protein and calcium, two components that help to buffer stomach acid before exercise can be helpful. Feed around 300 g within an hour of exercise.

Feeding starchy grain and grain-based concentrate feeds increases the risk of gastric ulcers, due to a combination of the lower amount of saliva produced during ingestion and the acid-enhancing effects on the stomach environment. Starch intake should be kept to a minimum or even avoided. Modern compound feeds containing high digestible fibre and elevated oil levels and low levels of starch should be chosen – ideally with a starch content as low as possible and definitely under 10%. Concentrate meals should be split between at least 3 meals daily.

Supplementary vegetable oil could help to reduce the risk of ulcers, by reducing gastric acid production and altering hormone production in the stomach. Evidence is limited, but adding 50-100 ml of vegetable oil to the diet of hard working horses may be helpful.

Antacids can help to reduce the effects of excessive gastric acid, but should not be used in an attempt to ameliorate the effects of feeding large amounts of dietary starch. Stomach-coating supplements such as mucilaginous herbs including marshmallow root and fat-based lecithin and the soluble fibre pectin have been used with success. Complexes of pectin and lecithin form a barrier on the stomach lining, protecting it against the corrosive effects of acid, and research studies have confirmed a protective and healing effect.

Free access to water also seems to reduce the risk of ulcers, so ensure fresh clean water is available at all times and offer water frequently whilst travelling.


Horses – particularly those kept for competition – are at high risk of gastric ulcers due to their physiology, the effects of exercise and the way they are kept. Careful management and feeding are necessary to reduce the risk of ulcers and keep the stomach healthy. The horse’s stomach is delicate and needs to be respected if it is to be kept healthy.

ReadySupp formulated the comprehensive supplement Grumpy Girth especially for hard working horses and equine athletes to help maintain a healthy gut and peak performance. Currently 90% of ReadySupp riders and trainers feed the supplement to their equine teams and are happy with the results.

Grumpy Girth

References: For more information, see Luthersson and Nadeau (2013 ) Gastric Ulceration, In Geor, R. J., Harris, P. A. & Coenen, M (eds) Equine Applied and Clinical Nutrition, Saunders Elsevier, Edinburgh.

If you have any questions on equine supplements, and want to improve your horse’s health, performance, or attitude give our friendly team a call 01672 541 157 for advice. We won’t try and hard sell you anything – we promise.

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