Gastric Ulcers in Horses

What Are Gastric Ulcers in Horses?

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

Humans only produce stomach acid while eating, but horses constantly produce stomach acid. Horse stomachs produce up to 9 gallons of acid per day, even when they are not eating. Stomach acid levels may be highest during exercise, and in between meals. Horses grazing out on pasture are much less likely to develop ulcers than high-end athletic horses.

Multiple studies have estimated the prevalence of gastric ulcers to be 30–50% in adult horses, and up to 90–100% in racehorses.

Signs of Gastric Ulcers in Horses

Signs your horse may be suffering from ulcers include:

• Poor appetite 

• Weight loss or loss of body condition

• Lethargy or dullness

• Behavior change—especially grumpy/irritability about being saddled or ridden

• Diarrhea

• Poor hair coat

• Grinding of teeth

• Poor performance

• Acute or recurrent colic, particularly after eating

• Frequent lying down

• Reluctant or slow to eat grain

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

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

What Causes Gastric Ulcers in Horses?

Gastric ulcers in horses have been said to be a “man-made disease,” meaning that humans have the condition by introducing changes in lifestyle and feed that are not natural for the horse. 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.

Many factors can contribute to ulcer formation in horses, from feeding them in a less-conducive way to their natural anatomical structure to keeping them in stressful environments. Factors that can lead to ulcer formation in horses include:

• Stress 

• Stall confinement 

• Chronic administration of medications, especially NSAIDS (i.e., Banamine® and Bute)

• 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 a flexible endoscopy of the stomach.

This procedure is the best way to diagnose ulcers in horses and can be performed on the farm, at a veterinary clinic, or in a hospital. The horse is commonly given mild standing sedation and a twitch may be placed on their nose; this puts pressure on the upper lip and releases endorphins while giving the horse something to focus on. These may be useful if the horse is shaking their head a lot or not staying still for the endoscopy.

During the procedure, a 3-meter fiberoptic scope is placed in the horse’s nose and passed through the esophagus into the stomach. The veterinarian will be able to visualize the surface of the stomach through a camera to look for any ulcers.

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 12 hours before the procedure

• Removing water three to four hours before procedure

• Some horses may require further fasting

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 FDA-approved ulcer medication for horses—omeprazole.

Omeprazole for horses is available as a prescription paste formulation called GastroGard® which has been effective at treating and preventing gastric ulcers. GastroGard® works by reducing the production of stomach acid by suppressing the proton pump within the stomach that secretes stomach acid.

Treatment with GastroGard® is recommended to be given once a day for a total of 28–30 days. A recheck endoscopy is generally recommended to monitor healing. If a horse is very painful and acts colicky after eating, they may also be prescribed sucralfate to coat the ulcers; these two medications should not be given at the same time of day, however, to be effective.

Caring for Horses with Gastric Ulcers

The prognosis is generally very good for horses with ulcers. Some horses may need to be weaned off of GastroGard® slowly or have other changes implemented as well to protect the stomach, as many horses experience recurrent ulcers after discontinuing the medication.

UlcerGard®, which has the same formulation as GastroGard®, is an OTC paste used for prevention of repeat ulcers so may be beneficial before and after a stressful event. Successful recovery and management may require omeprazole occasionally, but it is not recommended for long term use. Environmental, lifestyle, and feeding changes are also needed to reduce a horse's stress and predisposition for ulcer formation. Tips for quick recovery and lifelong management include the following:

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

• Offering stalled horses hay in slow-feeders may also help promote a more natural grazing schedule.

• Provide daily turnout time.

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

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

• Use gastric support supplements.

What To Feed Horses with Ulcers

Allow free-choice access to 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 meals to help aid the buffering of constant stomach acid.

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

Gastric ulcers can lead to more severe symptoms or disease including:

• Significant weight loss

• Colic

• Anemia 

• Perforation of the stomach wall

• Cast in stall 

Preventing Gastric Ulcers in Horses

Ulcer treatment for horses (as listed above) also serves as effective prevention.

If your horse is prone to ulcers, your veterinarian may discuss keeping your horse on an over-the-counter medication called UlcerGard®. UlcerGard® is given daily and is a half dose of GastroGard®. It has been shown to help with prevention of ulcers for 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.