Learn to read the vast and varied signs of equine gastric ulcer syndrome

The gelding that kicks the stall wall and acts aggressively toward his neighbors at feeding time. The show horse that’s increasingly more reluctant to perform under saddle. The angsty mare that’s always swishing her tail and grinding her teeth. Many owners observe these quirks in their horses and chalk them up to behavioral issues. But is it truly bad behavior or is it a sign of discomfort? As you’re about to find out, equine gastric ulcer syndrome (EGUS) might be to blame.

Stomach Anatomy Basics

The horse’s stomach has two regions: a nonglandular (squamous mucosa) portion comprising the upper third, and a glandular lower portion. The squamous nonglandular region doesn’t feature the thick, protective mucus and bicarbonate (a pH buffer) layer that the glandular region does, leaving it vulnerable to ulceration from gastric acid. 

Frank Andrews, DVM, MS, Dipl. ACVIM, LAIM, LVMA, equine committee professor and director of the Equine Health Studies Program at Louisiana State University’s School of Veterinary Medicine, in Baton Rouge, likens ulcers in the squamous mucosa in horses to gastroesophageal reflux disease (GERD) in humans, in which gastric acid damages the esophageal lining. 

“When the horse has an empty stomach or acid in the stomach due to stress, that acid may splash onto the nonglandular mucosa, especially when exercising,” he says, explaining that the hydrochloric acid the cells in the glandular mucosa produce might damage it.

While the stomach’s glandular region enjoys protective mechanisms such as prostaglandins that maintain mucus and blood flow, it’s not immune to ulcer issues, says Andrews. “The glandular mucosa is less susceptible to acid damage, but it is susceptible to stress, dehydration, and dietary issues,” he says.

Those dietary issues include high-sugar diets, Andrews explains, such as large amounts of sweet feed, which, when fermented by the stomach’s natural bacterial flora (microbiota), create short-chain fatty acids that can eat away at the stomach lining. Other factors can also contribute to glandular ulcers, such as non-steroidal anti-inflammatory drug (NSAID) use, including Bute (phenylbutazone), Banamine (flunixin meglumine), and even Equioxx (firocoxib), which Andrews notes researchers have recently determined can have some deleterious effects on the glandular stomach. 

Signs to Watch For

At the University of Pennsylvania School of Veterinary Medicine’s (Penn Vet) New Bolton Center, in Kennett Square, horses are sometimes video-monitored over a 24-hour period to assess behavioral patterns that might suggest physical discomfort, says Sue McDonnell, MS, PhD, CAAB, founding head of Penn Vet’s Equine Behavior Program. She notes that when horses exhibit attitude or performance changes, they often have gastric ulcers as a primary or secondary problem.

“In my experience, at least 60-70% of horses that have gastric ulcers show some sort of behavior suggesting discomfort around the time of feeding or whenever they have not had something to eat for a few hours,” she says. “The signs a horse might show are highly variable between individuals and might even be different within an individual over time.” These, say McDonnell and Andrews, might include:

• Looking back at or nosing the abdomen behind the shoulder, on both sides of the body. The coat might be ruffled where the horse nuzzles repeatedly;
• Acting anxious or restless in combination with clusters of behaviors suggesting physical discomfort (weight-­shifting, rotational headshaking, kicking up at the abdomen, tail-­swishing or -slapping, lip-licking, tongue extension, and chewing motion when not eating);
• Food-aggressive behaviors around feeding time, such as rushing to the feed bucket, pawing, threatening neighbors, and kicking the wall;
• Reluctance to perform;
• General grumpiness with herdmates and/or caretakers;
• Rough hair coat;
• Weight loss and poor body condition;
• Girthiness;
• Mild colic episodes;
• Intermittent eating patterns (leaving feed for a time and then returning);
• Teeth-grinding;
• Lack of energy;
• Decreased water intake;
• Stretching out as if needing to urinate;
• Lying down more than normal; and
• “Just not looking or acting right.”

“What we see are vague clinical signs, so we spend a lot of time talking with the owners, the trainers, and the people that handle the horse to see if they notice any of these things,” says Andrews.

McDonnell says that when comparing gastroscopy findings (those seen when the veterinarian views the horse’s stomach through an endoscope passed through his nostril and down the esophagus), some horses with minor ulceration might show dramatic behavioral changes, while horses with more extreme ulceration might exhibit only mild symptoms. “The message should be that individuals may have a varying response,” she says.

Arriving at a Diagnosis

“We know that if we are going to try to figure out the reason for a behavior change, we don’t want (the horse) to have ulcers on board at the time,” says ­McDonnell. “A wise first step is to have gastroscopy performed to establish from the beginning if the horse does or does not have gastric ulcers. For those with ulcers, the usual recommendation is to treat and then confirm healing with follow-up gastroscopy. If behavior problems remain, you can then work on figuring out what else might be bothering the horse.”

While the only definitive method of diagnosis is gastroscopy, says Andrews, owners and veterinarians can, in his opinion, consider treatment first. “We obviously like to have a diagnosis, but I don’t think it’s wrong for a practitioner to give a seven-day trial treatment with GastroGard (the trade name for omeprazole, used to treat stomach ulcers),” he says. To again draw an analogy to human medicine, Andrews says, “People experiencing dyspepsia (indigestion) don’t typically get scoped on the first visit; they might get a sample of Prilosec (omeprazole) or Nexium (esomeprazole) with the instructions to ‘Try these and call us back.’ ”

If the behavioral signs resolve with treatment, then you have your ulcer diagnosis, as omeprazole does not affect any other behavior-altering diseases, he says.

Andrews says recently introduced tests that measure blood in the manure to diagnose EGUS have not been fully validated yet in horses.

“The human card test, ‘guaiac test,’ was evaluated and found to be helpful when positive, but when negative, many of those horses had ulcers also,” he says. “The test was developed for people as a colon cancer screening test, but it’s less reliable in horses as a diagnostic test for stomach ulcers,” because blood in manure could come from anywhere in the GI tract.

Some horses with ulcers might have mild anemia, says Andrews, who suggests owners have blood drawn during horses’ annual checkups to establish a bloodwork baseline. “While levels may be within the normal range, if you follow the horse throughout the years, you may see the red blood cell count decrease, which could signal the horse is having an issue with ulcers.”

Treatment Plans

Omeprazole (again, GastroGard) and the lower-dose product (UlcerGard) are currently the only FDA-approved drugs for treating and preventing stomach ulcers in horses. While both products contain the same active ingredient, UlcerGard is designated for gastric ulcer prevention and GastroGard for treatment and prevention of recurrence. UlcerGard, says Andrews, delivers one quarter the dose of omeprazole that GastroGard paste does.

In addition, Andrews includes a supplement regimen. “Supplements like SmartGut Ultra (which contains sea buckthorn, pectin, lectin, glutamine, and aloe vera) do have some protective properties so, when we treat with GastroGard, I’ll simultaneously supplement with SmartGut Ultra to help maintain stomach health,” he says.

After the manufacturer’s recommended month of initial treatment, Andrews suggests tapering the GastroGard dose. “We’ll go from a typical 1,000-lb (horse) dose of 4 mg/kg to 1 mg/kg for two weeks before taking the horse off the medication,” he says. “GastroGard inhibits gastric acid secretion, but it leads to increased gastrin (a hormone) in the blood; that gastrin will stimulate parietal (stomach wall) cells after discontinuation of treatment, causing rebound hyperacidity.” Tapering the dose helps prevent this.

Good Horsekeeping

Certain management tactics can help ward off gastric ulcers and their accompanying negative behaviors.

“I don’t think horses should go more than about an hour without access to some sort of roughage, which appears to be quite protective against ulcers,” says McDonnell. “When horses are without hay, they begin to rummage around and may lick walls and chew on wood.”

Horses evolved as trickle feeders, she explains, meaning they are meant to graze or browse almost continuously, punctuated with short 30-minute rest breaks.

After treatment Andrews recommends owners try to mitigate ulcers by changing management strategies. “We recommend no more than 5 pounds (twice a day) of sweet feed,” he says. “Owners might feed more grain if it’s a low-sugar (low-starch) grain. Studies show adding corn oil (4 to 8 ounces, twice daily) to the diet helps increase mucous production and might increase blood flow by increasing protective prostaglandins (lipid compounds that behave like hormones) in the glandular portion of the stomach. In addition, corn oil supplementation will add energy to the horses’ diet and produce a shiny hair coat,” Andrews says.

He offers a few other general management strategies:

• Take advantage of pasture turnout;
• Minimize stress;
• Get the horse out of the stall and into a social group he gets along with; and
• If the horse is on phenylbutazone or flunixin meglumine, reduce the dose, if possible, or switch to firocoxib, which is a “COX-1 sparing,” or COX-2 selective drug; COX-1 is an enzyme that plays a role in protecting the stomach lining.

On the Road

Traveling, competing, and life on the road present their own set of challenges. Andrews recommends taking a proactive approach to maintain stomach health in the face of travel stress. He suggests:

• Bringing hay from home or having hay shipped in for a consistent diet;
• Considering feeding alfalfa, which increases stomach pH and neutralizes stomach acid, offering buffering effects;
• Encouraging water consumption by acclimating the horse to flavored water at home or offering one bucket of fresh water and one bucket with flavored gelatin or Gatorade added. Find a flavor the horse likes, so he will turn to the familiar taste of flavored water and drink more on the road, maintaining hydration and reducing stress;
• Adding a product comparable to Morton’s Lite Salt (potassium/sodium chloride mixture) to the grain to stimulate the desire to drink; and
• Administering preventive UlcerGard when shipping.

Andrews describes a new feed product, Purina Outlast, which he says the company tested on horses with heavy travel schedules. It features a proprietary calcified product touted for buffering stomach contents. While other buffering products do exist, they have not been tested as rigorously as this one, he says.

“Outlast supplement added to the grain prevented ulcers from becoming more severe compared to the horses fed the regular grain,” says Andrews. “This product might be helpful for horses in stressful situations and periods at risk for gastric ulcers, especially during travel.”

The Whole Horse

When addressing ulcer issues, McDonnell says the more natural environment the horse lives in, the less stress he’ll experience as a whole. “We often see horses return to the clinic with a relapse of ulcers. You do need to address the horse’s environment if you expect them to remain ulcer-free for long,” she says. “You have to look at the entire program, not just nutrition. Unfortunately, stressors of all types appear to contribute to ulcers, and ulcer discomfort itself is stressful, so there may be a downward spiral.”

While some horses are simply predisposed to ulcers, says Andrews, if you manage diet and stress, you can help minimize your horse’s possibility of getting them. And that makes for a happier horse and a happier you.