Digestion & Gastric Ulcers

The symptoms of stomach ulcers and the symptoms of being Grass Affected can be confusingly similar so therefore it is best not to leap to the conclusion that your horse has stomach ulcers without considering other causes.

Most common are gastric or stomach ulcers. The reason is that horses have a smaller stomach than other animals. This is why they cannot handle large amounts of food. Instead they are meant to graze for most of the day so periods of rest are short and the stomach is not empty for hours on end.


Food, Food, Food!

The more or less continuous ingestion of coarse, fibrous material, means horses require a steady flow of acid for digestion. A horse's stomach produces large amounts of acidic fluid 24 hours a day, 7 days a week, even in those periods of the day when they are not eating. Normally, this acid is partially neutralised by both the feed and saliva produced from chewing.

When horses are fed ‘meals’ without access to roughage in between, the stomach is subjected to a prolonged periods without feed to neutralize the acid. According to the veterinarian lecturing on this subject at Equitana, ulcers can start if the stomach is empty for as little as four hours.

Horses who are out at pasture 24/7 or otherwise housed with ad lib access to hay, are very unlikely to develop stomach ulcers. In fact the ‘cure’ for horses who have developed ulcers apart from a course of medication is 24/7 pasture turn-out or ad lib access to hay.

The clinical signs of ulcers include:
in Scientist’s Terms (Layman’s Terms)

  • Loss of appetite / Going off their feed
  • Weight loss
  • Episodes of Periprandial Colic ( Colic associated with feed time or riding )
  • Bruxism (tooth grinding )
  • Ructus ( yes, we had to look this up, and the definition turns out to be… ‘Eructation or belching of gas from the GI tract / otherwise known as FARTING )Why not just say this in the first place?!
  • Reflux ( Accumulation of fluid in the gut : Reflux occurs when the horse's intestines malfunction and stop absorbing fluids. Large amounts of fluid start to accumulate in the intestines, causing the gut, and eventually even the stomach, to swell and become painful.)

Gastric Ulcers are most common in horses that perform athletic activities. 80-90% of race-horses have been found to suffer from ulcers and it is no wonder.

We met a wonderful lady in Australia who works at a prominent racing stable where the horses are fed twice a day. The afternoon feeds are dished out between 2-3pm and she said they are well finished by 5.00pm leaving them with NOTHING to eat (or do) until between 6 & 7am the next morning! This is unbelievable! Knowing they want these horses to perform at their peak you would think they would be taking every step to avoid these horses developing the slightest hint of an ulcer!

Endurance and competition horses are not far behind race-horses. Apparently exercise not only increases gastric acid production and decreases blood flow to the gastrointestinal (GI) tract but also causes the acidic fluid in the stomach to splash around thereby subjecting the upper, more vulnerable portion of the stomach to an acidic pH.


Tawny with her haynet -this ensures that although she is in 'lock-up' for weight control, she never runs out of all-important hay!

Less obvious signs for stomach Ulcers include the following and you can see the similarities between these and signs of being ‘Grass Affected’.

The only way to confirm the presence of stomach ulcers is to have your veterinarian scope the horse.

Be aware that ulcers can also form further down the intestinal tract in the small intestine, the caecum and the hind-gut. These are obviously harder to diagnose.

  • Uncharacteristic behaviour (aggression, nervousness)
  • Poor performance
  • Agitation
  • Depression
  • Lying down more than normal.
  • General signs of discomfort.
  • Stereotypies such as Cribbing or wind-sucking

The take home message here is to make sure your horse(s) never run out of forage.

When transporting horses for long distances it is wise to stop and unload them every couple of hours so they can have a graze or some hay. A few hours of transport has been known to induce stomach ulcers in previously healthy horses..

Long term administration of some non-steroidal anti-inflammatory drugs (NSAIDs such as bute) are detrimental to the stomach's protective mucus layer, making it more susceptible to ulcers. (Short term use is absolutely fine and preferable to the horse enduring unnecessary pain)


Prevention and Treatment

As always, prevention is preferable to treatment. Feed horses frequently or on a free-choice basis. This helps to buffer the acid in the stomach and stimulate saliva production, nature's best antacid.

Acid in the stomach is there for a very good reason so horses should be treated only when a diagnosis has been confirmed.

There are several approaches in the treatment of ulcers in horses:

  1. Administer substances which NEUTRALISE the acid much like antacids in humans. However, for horses, the dose of antacids required to buffer the extremely low pH is very high and would need to be used several times a day to be effective.
  2. Or administer substances which INHIBIT THE PRODUCTION of acid. Omeprazole for instance stops stomach acid secretion completely so you can see why you would not want to be using it except when necessary.

There are other types of drugs which PARTIALLY block acid production.

Obviously any treatment needs to be accompanied by appropriate lifestyle changes to prevent recurrences. Rectifying the diet will increase chewing time and saliva production which is the nature’s way of partially neutralising stomach acid.