When it comes to managing gastric ulcers in horses, owners must take steps beyond simply administering anti-ulcer medications.

“Although treatment with omeprazole is effective in many cases of equine gastric ulcer syndrome (EGUS), we should not rely solely on medical therapy to manage gastric ulcers,” said Robin van den Boom, DVM, PhD, Dipl. ECEIM, an associate professor in the Department of Clinical Sciences at Utrecht University, in the Netherlands. “We must address husbandry practices and other known risk factors.”

In his recently published article in the Veterinary Journal (2022), van den Boom reviewed the two forms of EGUS—equine squamous gastric disease and equine glandular gastric disease—and their associated risk factors.

Equine Squamous Gastric Disease

Equine squamous gastric disease (ESGD) affects the squamous, or nonglandular, region of the stomach—the upper area above the normal level of gastric juice and digesta. Van den Boom said ulcers in the nonglandular region are thought to occur because of the splashing of the acidic gastric juices and exposure to volatile fatty acids.

Key risk factors for ESGD include:

• Forage deprivation for more than six hours, because reduced access to forage decreases saliva production—and saliva buffers gastric pH. Forage might also form a “splash guard,” preventing the gastric juices from touching the stomach’s squamous region.
• A diet high in concentrates/starch/carbohydrates.
• A diet in which straw is the only forage available.
• Lack of access to water at pasture.
• Stress.

“There is now some (circumstantial) evidence that stress also plays a role in the development of ESGD,” said van den Boom. “Training, competition and travel are known to cause stress. Other stressors (in my opinion) are being low in the group hierarchy, unpredictability in the (daily) routine, interaction with certain horses and/or humans, moving to new premises, and loss of a companion (another horse).”

Equine Glandular Gastric Disease

While equine glandular gastric disease (EGGD) is much less frequently described in the literature than ESGD, it’s equally important, said van den Boom. These lesions occur in the glandular, or lower, region of the stomach, which is always in direct contact with the acidic gastric juices. Unlike what happens with squamous disease, physical/chemical damage due to the acidic liquid does not contribute to EGGD.

“The glandular portion of the stomach produces mucus and bicarbonate, which protect the stomach lining and neutralize the stomach acid,” van den Boom said. “This production (mediated by natural chemicals in the body called prostaglandins) may be decreased because of compromised blood flow.”

Key risk factors for EGGD are distinct from ESGD and have more to do with management than diet. Specifically, exercise intensity—exercising more than five times per week—appears to be one of the most important contributing factors to EGGD. In addition, the trainer or the presence of multiple caretakers were found to be risk factors.

“There is fairly strong evidence that stress plays a role in EGGD development,” van den Boom added.

Preventing Gastric Ulcers in Horses

Avoiding these risk factors can help reduce EGUS prevalence, which is very high in certain populations (see sidebar). However, many owners of performance horses can’t alter their horses’ management easily.

What options do these owners have to help minimize EGUS? Continued omeprazole therapy is possible, but simply giving a medication to heal ulcers and prevent their recurrence without addressing why the horse is continually at risk is a questionable management approach, said van den Boom.

He noted that we should try to prevent new ulcers by adapting the horse’s management and avoiding risk factors and stressors to the best of our abilities.

“At the moment I try to make sure the horse’s dietary management is optimal,” van den Boom said. “In addition, I think horses fare well by a regular/predictable routine with people and other horses they ‘like,’ although I don’t know exactly how to assess that (scientifically).”