Gastric ulcers are sores in the stomach lining that can affect horses at any age, potentially resulting in colic signs and decreased performance. Every horse is susceptible to gastric ulcers, but the condition most often affects racing, endurance, and show horses. Our Bear Creek Large Animal Clinic team provides information about equine gastric ulcer syndrome (EGUS), so you know what to expect if your horse develops the condition.

What is equine gastric ulcer syndrome?

EGUS is an umbrella term that collectively refers to ulcers that occur in the squamous and glandular stomach regions. The equine stomach has two distinct regions. The squamous region makes up about one-third of the equine stomach, has no glands, and is covered in stratified squamous epithelium, a tissue similar to that of the esophagus. The glandular region makes up the remaining two-thirds of the equine stomach, and contains glands that secrete hydrochloric acid, pepsin, bicarbonate, and mucus. A cellular ridge (i.e., the margo plicatus) separates the equine stomach’s regions. Ulcers can affect either or both stomach regions:

  • Equine squamous gastric disease (ESGD) — ESGD refers to ulcers in the squamous stomach region, and accounts for about 80% of equine ulcers. Prevalence is highest in performance horses, but the condition has been diagnosed in many breeds and ages, including feral horses and foals. ESGD occurs when the squamous mucosa experiences sustained acid exposure. A horse’s squamous mucosa has a poor blood supply and lacks a protective barrier, making this stomach region especially susceptible to acid injury. ESGD can be primary, caused by intensive management related to domestication, or secondary, caused by delayed gastric emptying, which leads to chronic gastric distention and prolonged squamous mucosa exposure to acid. 

  • Equine glandular gastric disease (EGGD) — EGGD refers to ulcers in the glandular stomach region. EGGD research is limited, but preliminary data suggest performance horses, especially Thoroughbreds and warmbloods, are most commonly affected. EGGD’s cause is not well understood. The glandular region has numerous protective factors to prevent acid from injuring the tissue. Potential contributing factors include spontaneous mucosal defense breakdown, bacterial colonization, stress, and inflammation.

What are equine gastric ulcer syndrome signs?

Many horses affected by EGUS exhibit no signs and appear healthy. However, subtle EGUS signs may include:

  • Decreased appetite
  • Lethargy
  • Irritability
  • Decreased performance
  • Training difficulties
  • Poor body condition
  • Poor hair coat
  • Weight loss
  • Low-grade colic signs (e.g., curling the lip, occasional pawing while eating, looking at their flank, grinding their teeth)
  • Girthiness

In severe cases, horses can exhibit more serious colic signs such as inappetence and rolling. Being on their back seems to provide relief for severe gastric ulceration. Foals’ EGUS signs include intermittent colic, especially after nursing or eating, frequent recumbency, reduced nursing, diarrhea, teeth grinding, and a pot-bellied appearance.

How is equine gastric ulcer syndrome diagnosed?

Click here to watch a quick video of our team taking a biposy of a mass from one of our patients.

The only way to definitively diagnose gastric ulcers is through gastroscopy, which involves passing an endoscope up the horse’s nostril, down their esophagus, and into the stomach to look at the surface lining. This procedure helps differentiate EGSD from EGGD, and can also identify other stomach conditions such as stomach bots. Gastroscopy is minimally invasive, typically requiring only light sedation and potentially a twitch for restraint. This procedure provides valuable information about a horse’s esophagus, stomach, and small intestine. 

How is equine gastric ulcer syndrome treated?

EGUS treatment involves removing the predisposing factors and decreasing stomach acid production. Strategies include:

  • Feed — When possible, affected horses should be allowed free-choice access to grass or hay. More frequent feedings help buffer the stomach’s acid. Volatile fatty acids ([VFAs] i.e., fermentation carbohydrate byproducts) can induce acid injury to the squamous region acid injury, and reducing grains that form VFAs may help some horses. 
  • Medications — Omeprazole is the only U.S. Food and Drug Administration (FDA)-approved medication to treat EGUS. The medication is an acid pump inhibitor that is administered as a paste once daily for 28 days. Other less-expensive compounded products are available, but studies have demonstrated a lack of active ingredient and decreased effectiveness when compared with the approved drug. Other medications, such as sucralfate, may also treat EGUS effectively.

How is equine gastric ulcer syndrome prevented?

EGUS is common in horses. However, you can help lower your horse’s EGUS risk by following these management techniques:

  • Feeding horses frequently — Feed horses frequently or on a free-choice basis to help buffer stomach acid and stimulate saliva production, which acts as an antacid.
  • Reducing concentrates — Reduce your horse’s grain amount and consider adding alfalfa hay to their diet. Always discuss any diet changes with Dr. Church, so he can determine if the change will meet your horse’s nutritional needs and avoid interfering with medical issues. 
  • Avoiding anti-inflammatory drugs — Avoid or decrease the amount of anti-inflammatory drugs you give to your horse. Nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids can damage the stomach lining. 
  • Limiting stress — Limit stressful situations such as intense training and frequent transporting. As a preventive measure, you can also administer a half dose of omeprazole before a potential stressful situation.
  • Stalling considerations — If your horse must be stalled, ensure they can see and socialize with other horses and have access to forage. Some horses seem to enjoy having a ball or other toy in their stall to keep them occupied.

If you are concerned that your horse has developed EGUS, contact our Bear Creek Large Animal Clinic team to schedule a gastroscopy. We will evaluate your horse’s condition and devise an effective treatment strategy.