Equine Gastric Ulcers

Equine Gastric Ulcers

article by Jill Firth - PGDip AM(Dist)

Gastric (or stomach) ulcers can happen in all types of horses. Recent surveys suggest that around 90% of racehorses, 60% of competition horses and 35% of leisure horses can suffer with stomach ulcers. Foals can be particularly at risk with up to 50% having some degree of stomach discomfort.

Horses are “trickle feeders” who eat little and often. In the wild they spend as much as 18 hours or more every day, eating forage. Their digestive system has evolved to cope with this by producing large volumes of acid to digest the large amounts of roughage they consume naturally. All horses produce acid constantly whether they are eating or not, and their stomachs are largely able to cope with this as the lower part of the stomach is covered in a membrane which protects it from acid burning, however the upper part of the stomach has no such protection.


Basically problems occur when there is too much acid in the stomach.

Horses who have restricted access to roughage in the form of grass, hay or haylage, are at risk as the stomach keeps producing acid but there isn’t enough roughage to buffer it and reduced chewing means reduced production of bicarbonate rich saliva which also neutralises stomach acid.

Horses on high grain diets (high starch, low fibre) are at risk because the food doesn’t stay in the stomach long enough and it doesn’t need much chewing.

Horses who are exercised intensely, for example racing, dressage, jumping etc, are at risk, as the stomach is compressed by the diaphragm and other organs during exercise which forces the acid up into the unprotected part.

Horses suffering from stress are at risk as they can have increased levels of corticosteroids and a subsequent reduction in blood flow to the stomach lining which then interferes with the protective coating and can lead to damage from the gastric acid. Stressful situations include training, travelling, weaning, stabling, moving yards, competitions, etc.

And whose horse has not run out of hay overnight when you get there in the morning leaving them with acid being produced but nothing to buffer it with?

Ulcer Symptoms in horses

Symptoms can be very vague and differ greatly from one horse to another. Some signs include:

  • Poor condition
  • Dull coat
  • Loss of appetite
  • Picky feeder
  • Lack of performance
  • Dull and lethargic
  • Reluctance to exercise
  • Girthiness
  • Changes in behaviour and/or general grumpiness
  • Crib biting or windsucking
  • Intermittent colic
  • Diarrhoea

Diagnosis and Treatment

A long endoscope (gastroscope), two to three metre long passed down into the horse’s stomach will allow the Vet to confirm the presence, severity and location of any ulceration. The most common location for ulcers is the upper part of the stomach but ulcers can develop in other areas of the digestive system including the hind gut.

The most effective treatment is omeprazole, which is an acid inhibitor. It works by shutting off some of the acid pumps allowing the ulcers to heal. Healing time varies depending on severity and the individual but is usually between 2 and 4 weeks.

However, “once an ulcer horse always an ulcer horse” so preventative measures have to be put in place.

Prevention of stomach ulcers in horses

  • Trying to mimic the horse’s natural environment is the best prevention but not always possible particularly for competition horses.
  • A regular low dose of omeprazole will benefit horses at risk or horses prone to gastric ulcers, particularly at times of stress such as competitions etc.

Other ways of preventing equine ulcers:

  • Feeding the concentrated feed little and often rather than in 2 or 3 feeds a day.
  • High fibre, low starch, low sugar diets
  • Constant access to roughage
  • Regular turnout, even just a few hours a day
  • Reducing stress where possible
  • Giving a couple of handfuls of Alfalfa pellets before exercise has been shown to be beneficial as it provides a "fibre mat" to help reduce acid splashing up. Also research suggests that Alfalfa buffers more acid than other grasses.


There are many supplements on the market claiming to help with gastric ulcers, mostly these are antacids which buffer/neutralise stomach acid but have a limited effect due to the sheer volume of acid which is produced constantly. Other supplements do contain other nutrients which help to promote production of mucous and strengthen the protective linings throughout the gut.

However, the overall key to gastric heath is management – You need to find a management plan which works for your horse. Management of the gastric ulcer prone horse can be extremely expensive, especially when a regular dose of omeprazole is required and unless covered by insurance can be prohibitive.

However, there are alternatives available - see here for more information.

© Jill Firth PGDip AM(Dist) 2000 - this article may not be partly or wholly copied, reproduced or quoted without prior written consent of the author

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