A Complete Guide to Gastric Ulcers in Horses

Gastric ulcers affect 69% of horses, according to Tufts School of Veterinary Medicine. But some horse breeds are particularly susceptible. For example, 93% of endurance horses and 70% of racehorses develop ulcers.

If your horse has gastric ulcers or you suspect that they might have ulcers, then you’ll want to read our complete guide to gastric ulcers in horses. We’ll cover types of ulcers in horses, causes, symptoms, and possible treatment.

If you are concerned about your horse by the end of this article, you should make an appointment with your equine veterinarian. Unfortunately, the only way to know for sure that your horse has ulcers is to be evaluated by a vet.

What Is a Gastric Ulcer in Horses?

Gastric ulcers in horses are legions in the stomach lining. Horses secrete gastric acid continually throughout the day. This is entirely healthy for horses that can forage small meals throughout the day. 

Gastric ulcers develop when a horse is fed larger meals that are more spread apart, allowing the horse’s stomach to empty. When there is nothing for the stomach acid to break down, it erodes the stomach lining

Two Types of Gastric Ulcers in Horses

Gastric ulcers develop in two areas of a horse’s stomach. 

Squamous Gastric Ulcers (ESGUS)

ESGUS develops in the squamous area of a horse’s stomach, which is the upper third of the stomach. Lesions will occur when bacteria, parasites, or excessive stomach acid damage the mucosal lining of the squamous. 

The squamous lack protection against bacteria, parasites, and stomach acid, so ESGUS is a very common ulcer in horses. Thoroughbred and Standardbred racehorses are especially susceptible. 

An NCBI study found that for Thoroughbred racehorses and Standardbred racehorses, ESGUS increased to 80%-100% within 2-3 months of training. 

Glandular Gastric Ulcers (EGGUS)

EGGUS occurs in the glandular area of a horse’s stomach. While this region of the stomach is built to withstand gastric acid, sometimes the mucosal lining deteriorates. When this happens, legions and inflammation develop in the glandular area.

Like ESGUS, racehorses are more susceptible to developing EGGUS because of their training and diet. However, only 47%-65% of Thoroughbred and Standardbred racehorses suffer from EGGUS. 

Interestingly, another NCBI study found that EGGUS was more likely to develop in inexperienced racehorses. For every year that a racehorse gains experience, the less susceptible they became to EGGUS.

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What Causes Gastric Ulcers in Horses? 

Several factors can cause gastric ulcers to develop in horses:

  • High-concentrate, low-roughage diets
  • Rapid diet changes, especially of high amounts of grain
  • Limited turnout
  • Rigorous interval exercise and training
  • Limited foraging
  • Stress
  • Frequent travel and new stall confinement
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Competition
  • Bacteria
  • Parasites

While these are the most common factors, other factors can contribute to developing ulcers in horses. Routine and breeding also contribute. 

Symptoms of Gastric Ulcers in Horses

It is not always apparent if your horse has an ulcer. Some horses may show no outward symptoms. Common symptoms of gastric ulcers are: 

  • Changes in behavior while being fed
  • Aggression
  • Low white blood cell count
  • Lack of energy 
  • Changes in behavior while being ridden
  • Decreased appetite
  • Weight loss or poor body condition 
  • Chronic diarrhea
  • Grinding teeth
  • Acute or recurrent colic 
  • Poor coat condition
  • Poor performance

These symptoms could also be related to other illnesses and diseases. If your horse has many of these symptoms, it may be time to call the veterinarian. The best method of diagnosing ulcers is gastroscopy.

It is crucial to diagnose ulcers to determine which type of gastric ulcers your horse has because ESGUS and EGGUS need to be treated differently to heal the ulcers.

Horse Ulcer Treatment 

It is important to consult with your veterinarian before treating your horse for ulcers, mainly because they will prescribe different treatments depending on if the horse has ESGUS or EGGUS. 

Treating ESGUS

Your vet may prescribe several treatment options depending on how severe the ulcers are: 

  • Omeprazole is a prescription drug that suppresses gastric acid production to give the stomach tissue time to heal.
  • Mucosal protectants to create a barrier between the acid and the stomach lining.
  • Antacids to temporarily reduce acid.
  • nutritional digestive supplement to fortify gut health.
  • A low concentrate, high roughage diet to normalize acidity levels.

Treating EGGUS

To treat EGGUS, your vet may prescribe:

  • Omeprazole for suppressing gastric acid production.
  • Sulcrafate or pectin-lecithin to heal ulcers and inflammation.
  • Antibiotics if bacteria are present.
  • nutritional digestive supplement to fortify gut health.
  • A low concentrate, high roughage diet to normalize acidity levels.

Preventing Ulcers in Horses 

The best defense against gastric ulcers is promoting a healthy diet and exercise habits. While this may be near impossible for racehorses, you can alleviate some of the stress placed on the horse by:

  • Reducing grain in their diet.
  • Offering continuous foraging on hay and grass.
  • Limiting or eliminating anti-inflammatory drugs.
  • Creating a calm environment for transportation 
  • Reducing training intervals.
  • Allowing turnout with other horses.

According to Kentucky Equine Research, all horses should eat 1.5 to 2% of their body weight in forage daily for overall digestive health and motility. And horses shouldn’t go longer than four or five hours between forage meals.

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Is your horse struggling to maintain weight? Rogue Pet Science equine supplements can significantly improve your horse’s overall gut health.


  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4858038/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6049336/
  3. https://pubmed.ncbi.nlm.nih.gov/25287371/
  4. https://ker.com/equinews/gastric-ulcers-in-horses-facts-and-fallacies/
  5. https://allabouthorses.org/

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