Gastric ulcers are actually quite common in horses. The prevalence of gastric ulcers in equine species has been estimated to be from 50% to 90%, depending on the populations being surveyed and type of activity in which the horses are engaged.¹

Unlike ulcers in humans, bacteria do not appear to cause gastric ulcers in horses. The reason for this is that horses are grazing animals; as such, they require a regular intake of roughage. Since the horse’s stomach continually secretes acid, gastric ulcers can result when the horse is not eating regularly enough due to there being less feed to neutralize stomach acid.²

Gastric ulcers can affect any horse at any age. Foals are particularly susceptible to ulcers  because they secrete gastric acid as early as two days of age, and the acidity of the gastric fluid is high as compared to adult horses. Foals that have infrequent or interrupted feeding, or are recumbent for long periods have been found to have lower gastric fluid pH (aqueous solutions with a pH less than 7 are acidic), suggesting that milk has a protective effect against ulcers and that recumbency increases exposure of the stomach to acid.¹

In adult horses, gastric ulcers occur more frequently in horses that perform athletic activities, with the highest frequency found in Thoroughbred racehorses (80-90%), followed by endurance horses (70%), and show horses (60%).¹ Researchers have found that exercise increases gastric acid production and decreases blood flow to the gastrointestinal (GI) tract. Additionally, when horses are engaged in physical activity, the acidic fluid in the stomach splashes and exposes the upper, more vulnerable portion of the stomach (squamous mucosa) to an acidic pH.²

Other risk factors for developing gastric ulcers include physical and environmental stress such as transport stress and stall confinement. Recent studies have demonstrated that a few hours of transport can induce gastric ulceration in horses that had none prior to departure, as determined by gastroscopy. Finally, the chronic administration of some non-steroidal anti-inflammatory drugs (NSAIDs) can decrease the production of the stomach’s protective mucus layer, making it more susceptible to ulcers.

Gastric Ulcers in Horses: Symptoms and Diagnosis

The majority of horses with gastric ulcers do not show outward symptoms, typically developing more subtle ones. Thoroughbred and Standardbred racehorses with poor performance are reported to have a higher incidence of squamous gastric ulcers. More serious cases will show abdominal pain (colic) and/or bruxism (grinding the teeth).²

Some of the more subtle signs exhibited in the case of gastric ulcers (which often go unnoticed) include:

• Poor appetite
• Dullness
• Attitude changes
• Decreased performance
• Reluctance to train
• Poor body condition
• Poor hair coat
• Weight loss
• Excessive time spent lying down
• Low-grade colic
• Loose feces

More serious cases will show abdominal pain (colic) and/or grinding of the teeth. Some horses are found on their backs, commonly seen in foals, since this position seems to provide some relief from severe gastric ulceration. Others will walk away from food for a period of time as if they experience discomfort when the food first hits the stomach.¹

The only way to definitively diagnose equine ulcers is through gastric endoscopy, or gastroscopy, which involves placing an endoscope into the stomach and looking at its surface. This procedure is easy to perform, is minimally invasive, and allows the veterinarian to evaluate the esophagus, squamous and glandular regions of the stomach, and proximal segment of the small intestine.² In order to do this, the horse’s stomach must be empty, so most horses are fasted for 12 to 24 hours and not allowed to drink water for two to three hours prior to the procedure.

Gastric Ulcers in Horses: Treatment

Prevention of ulcers is critical, and certainly more desirable to treatment. Limiting stressful situations, frequent feedings and free-choice access to grass or hay can go a long way toward the prevention of gastric ulcers. Such measures provide a constant supply of feed to neutralize the acid and stimulate saliva production. There are many supplements on the market that claim to prevent squamous gastric ulcers, but horse owners are advised to utilize preventative products that have been validated in competent scientific studies or recommended by their veterinarian because many are ineffective and lack validation.

Medication to decrease acid production is only necessary in horses showing clinical disease or when predisposing factors cannot be removed (i.e., horses in race training or show campaigning). While antacids can be an acceptable stopgap measure, they generally need to be administered six to 12 times a day in order to be effective. Antacids in feeds are relatively ineffective because they are ingested at the same time as the feed, which buffers the acid.

Sucralfate

A negligible amount of an oral dose is absorbed into systemic circulation and excreted in urine unchanged within 48 hours.⁴ Dissolving tablets in water before administration to dogs and cats is recommended to increase availability of drug, as tablet fractions have been observed in dog feces.⁵

Omeprazole

In one study, researchers used six horses treated with either 1 mg/kg or 4 mg/kg of omeprazole while receiving either a high-grain/low-fiber diet or a diet comprised of free-choice hay. The “area under the curve” (AUC), which is a measure of how much of the body is exposed to the drug after administration, was higher in horses treated with 4 mg/kg rather than 1 mg/kg of omeprazole. Although the AUC was higher in horses treated with omeprazole and fed a high-grain/low-fiber diet rather than hay, the difference between the two groups was not statistically significant.¹⁰

Omeprazole is contraindicated in patients hypersensitive to it or other proton pump inhibitors. In patients with hepatic or renal disease, the drug’s elimination half-life may be prolonged, and dose adjustment may be necessary if the disease is severe.¹

Sucralfate vs. Omeprazole

While sucralfate and omeprazole are both used to treat ulcers and gastroesophageal reflux disease (GERD) in horses, there are distinct differences between the two, and occasionally one is preferred in treatment over the other. Some of these differences include the following:

• Sucralfate and omeprazole belong to different drug classes. Sucralfate is an anti-ulcer drug and omeprazole is a proton pump inhibitor (PPI).
• Omeprazole is also used to treat Zollinger-Ellison syndrome, duodenitis, erosive esophagitis, heartburn, and H. pylori infection.
• Some versions of omeprazole are available over-the-counter (OTC).
• Side effects of sucralfate and omeprazole that are similar can include headache, dizziness, diarrhea, nausea, and vomiting.
• Side effects of sucralfate that differ from omeprazole include constipation, insomnia, vertigo, indigestion, dry mouth, dizziness and gas.
• Side effects of omeprazole that are different from sucralfate include rash, nervousness, abnormal heartbeat, muscle pain, and weakness.¹¹

Where to buy Sucralfate + Omeprazole

Sucralfate + Omeprazole is available in the U.S. through veterinary custom compounding companies. Common forms are oral suspension and paste. 

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

¹TheHorse.com.

²McClure, S., DVM, et. al. Equine Gastric Ulcers: Special Care and Nutrition. In: American Association of Equine Practitioners, July 2016.

⁴Sucralfate (adult and pediatric). In. Bethesda, Maryland: American Society of Health-System Pharmacists; 2009.

⁵KuKanich K, KuKanich B, Guess S, Heinrich E. Effect of sucralfate on the relative bioavailability of enrofloxacin and ciprofloxacin in healthy fed dogs. J Vet Intern Med. 2016;30(1):108-115.

⁶EquiNews.

⁷Marks SL, Kook PH, Papich MG, Tolbert MK, Willard MD. ACVIM consensus statement: support for rational administration of gastrointestinal protectants to dogs and cats. J Vet Intern Med. 2018;32(6):1823-1840.

⁸KuKanich K, KuKanich B, Harris A, Heinrich E. Effect of sucralfate on oral minocycline absorption in healthy dogs. J Vet Pharmacol Ther. 2014;37(5):451-456.

⁹KuKanich K, KuKanich B. The effect of sucralfate tablets vs. suspension on oral doxycycline absorption in dogs. J Vet Pharmacol Ther. 2015;38(2):169-173.

¹⁰Mason LV, Moroney JR, Mason RJ. Prophylactic therapy with omeprazole for prevention of equine gastric ulcer syndrome (EGUS) in horses in active training: A meta-analysis. Equine Veterinary Journal. 2019;51(1):11-19.

¹¹Medicinenet.com.