Gastric Ulcers in Horses: Signs, Treatment, and Prevention

Gastric ulcers in horses can be disruptive to training, showing, and the overall well-being of any horse. It's important to understand how gastric ulcers form and how they can be treated and prevented in your horse.

What Are Gastric Ulcers in Horses?

Equine gastric ulcer syndrome (EGUS) is a common health concern and can affect any horse at any age. EGUS are sores or defects in the lining of the stomach wall that develop due to irritation by stomach acid.   

A horse's stomach can be divided into two parts: glandular and non-glandular.

• The bottom part of the stomach is the glandular region, where stomach acid is produced and created to help with digestion.

• The top portion of the stomach is non-glandular, also called the squamous portion of the stomach. This is where most mixing of food happens, and it’s the most common site of ulcer formation because it does not have a protective coating to help prevent damage from stomach acid like the glandular region.

Humans only produce stomach acid while eating, but horses constantly produce stomach acid. A horse stomach produces up to 16 gallons of acid per day, even when a horse is not eating. Stomach acid levels may be highest during exercise, and in between meals.

Horses grazing out on pasture are generally much less likely to develop ulcers than high-end athletic horses.

Multiple studies have estimated the prevalence of gastric ulcers to be over 60% in working adult horses, and up to 90–100% in racehorses.

Signs of Gastric Ulcers in Horses

Signs your horse may be suffering from ulcers may include:

• Behavior change—especially irritability when being saddled or ridden

• Poor performance

• Poor appetite 

• Lethargy or dullness

• Frequent lying down

• Weight loss or loss of body condition

• Poor hair coat

• Frequent episodes of being cast or stuck in a stall—some horses (especially foals) get pain relief from ulcers by laying upside down

• Acute or recurrent colic, particularly after eating

In recent years, studies show that some horses may not even exhibit outward signs (or that those signs go unrecognized) when dealing with stomach ulcers. But if your horse is showing any of the above symptoms, contact your veterinarian.

What Causes Gastric Ulcers in Horses?

Many factors can contribute to ulcer formation in horses, such as feeding them in a way that is less conducive to their natural anatomical structure or by keeping them in stressful environments.

For example, feeding horses two large meals a day, rather than free grazing, leaves the stomach vulnerable to irritation by the acid and enzymes constantly produced by the glandular portion of the stomach. Stress can also increase stomach acid that can irritate the stomach lining.

Factors that can lead to ulcer formation in horses may include:

• Stress 

• Stall confinement 

• Chronic administration of medications, especially NSAIDS like flunixin and phenylbutazone (research on this topic is ongoing)

• Feeding large grain meals

• Prolonged periods of no roughage 

• Traveling

• Heavy exercise or workload

Diagnosing Gastric Ulcers in Horses

To diagnose stomach ulcers in horses, your veterinarian will start with a history and physical exam.

If your veterinarian believes gastric ulcers could be affecting your horse, they will likely recommend an endoscopic examination, or “scope,” of the stomach.

This procedure involves placing a 3-meter or longer video endoscope in the horse’s nose and passing it through the esophagus into the stomach.

The veterinarian will be able to examine the surface of the stomach through a camera to look for any ulcers or other abnormalities. A horse is commonly given a mild standing sedation for a scope exam.

Scoping is the best way to diagnose ulcers in horses and can be performed on the farm, at a veterinary clinic, or in a hospital. Most horses tolerate this procedure very well with little to no side effects.

Some preparation is involved with endoscopic procedures so the veterinarian can see the stomach clearly. Your vet will provide the necessary guidelines before the procedure, but these generally include:

• No food for at least 14 hours before the procedure

• Removing water two to three hours before procedure

• Some horses may require muzzling during the fasting procedure to prevent them from eating bedding or manure

Gastric Ulcer Treatment for Horses

Depending on the severity of the ulcers, treatment is aimed at removing the predisposing factors and decreasing the acid production to allow ulcers to heal.

Currently there is only one ulcer treatment approved by the Food and Drug Administration for horses, called GASTROGARD® (omeprazole), which has been effective at treating and preventing recurrence of gastric ulcers.

GASTROGARD works by reducing the production of stomach acid by suppressing the proton pump within the stomach that secretes stomach acid.

GASTROGARD is recommended to be given once a day for a total of 28 days. A recheck endoscopy is generally recommended to monitor healing.

The safety of GASTROGARD paste has not been determined in pregnant or lactating mares. GASTROGARD is for use in horses and foals 4 weeks of age and older.

In some cases, a horse may also be prescribed sucralfate to coat the ulcers. However, sucralfate and GASTROGARD should not be given at the same time and dosage should be separated by approximately 30 minutes.

Caring for Horses with Gastric Ulcers

The prognosis is generally very good for horses with ulcers. After treatment, some horses may need to be maintained on preventative doses of omeprazole, especially if management changes are difficult to put in place.

Successful recovery and management of an equine ulcer may initially require omeprazole, but it is more ideal to maximize environmental, lifestyle, and feeding changes to reduce a horse's stress and predisposition for ulcer formation. 

Tips for quick recovery and lifelong ulcer management include:

• If a horse must be stalled, prioritize socialization by placing them near other horses or offering stall toys, such as a ball.

• Offer stalled horses hay in slow-feeders to help promote a more natural grazing schedule.

• Provide daily turnout time.

• Consider gastric support supplements (look for those with peer-reviewed research to support them).

• Avoid or decrease frequency of any anti-inflammatory medications when possible.

• Limit stressful situations, such as high-level training or frequent traveling, if possible.

What To Feed Horses with Ulcers

Encourage continual consumption of free-choice grass or hay for ulcer-prone horses. Horses are meant to graze all day with a constant intake of roughage. 

Additionally, feed small, more frequent concentrate meals to help aid the buffering of constant stomach acid.

Your horse may also benefit from being fed a gut health supplement as mentioned above. These products may help support the stomach lining.

Finally, decrease grain meals or high-starch concentrates that form volatile fatty acids. These feeds are generally higher in carbohydrates, such as sweet feeds.

Preventing Gastric Ulcers in Horses

Ulcer treatment for horses also serves as effective prevention.

If your horse is prone to ulcers, your veterinarian may discuss using ULCERGARD® (omeprazole) during times of stress. ULCERGARD is given daily and is a quarter dose of GASTROGARD. It has been shown to help with prevention of ulcers in some horses.

Encouraging long periods of grazing, rather than large grain meals twice a day, is beneficial for horses prone to ulcers. Offering a small amount of hay before exercise may also help lessen irritation of the upper stomach by acid and digestive enzymes during strenuous movement.

Digestive or calming supplements for gastric ulcers in horses may also be recommended by your veterinarian to help with preventing ulcers, depending on your horse's lifestyle and personality.