Treating Gastric Glandular Disease in Horses
Not all equine gastric ulcer syndrome cases are the same. In fact, in 2015 researchers split the condition into two categories—equine glandular gastric disease (EGGD) and equine squamous gastric disease (ESGD)—because of each one’s distinct pathology, risk factors, diagnostics, and treatment approaches.

At the 2017 American Association of Equine Practitioners convention, held Nov. 17-21 in San Antonio, Texas, Heidi Banse, DVM, PhD, Dipl. ACVIM (LA), described how to manage the more problematic of these two diseases: EGGD.

Equine squamous gastric disease affects the upper squamous region of the horse’s stomach, which is unprotected from gastric acid. Equine glandular gastric disease involves the lower region. Its prevalence depends on riding discipline and horse breed but ranges from 10% to 65%, said Banse, a veterinary specialist in Louisiana State University’s Department of Veterinary Clinical Sciences, in Baton Rouge.

The condition’s prevalence is high among Warmbloods and sport horses (46-65%). In preliminary findings from one study, she said, exercise frequency and performance level were associated with an increased risk of EGGD in show jumping Warmbloods, while feeding and exercise regimens appear to contribute to increased risk of EGGD in Thoroughbred racehorses.

After confirming EGGD via gastroscopy, Banse suggested veterinarians use both of the available scoring systems—the European College of Equine Internal Medicine glandular lesion description and the modified EGUS scoring system—to characterize disease severity and monitor improvement.

When it comes to treating EGGD, omeprazole (GastroGard, not the generic or compounded types, she said) remains the gold standard; however, said Banse, glandular disease tends to be more challenging to treat than squamous. She cited one study in which 86% of Grade ≥2 ESGD horses healed after a 28-day omeprazole regimen, while only 14% of Grade ≥2 EGGD horses healed. In the same study 96% of ESGD horses showed improvement vs. 34% of EGGD horses.

While the reason for this disparity is unknown, “diet and duration of fasting prior to omeprazole administration may impact the drug’s pharmacokinetics and pharmacodynamics,” Banse said. Previous research supports the following feeding regimen: offering EGGD horses their evening meal, withholding hay and feed overnight before administering GastroGard, and continuing to withhold feed for 90 minutes post-administration.

One study’s authors suggested adding the protectant sucralfate to the omeprazole dose, after observing a 65% healing rate when combining the two drugs. Another’s suggested the hormone misoprostol alone might be more effective (73% returned to normal) than omeprazole plus sucralfate (22%).

Researchers have also tried treating this condition with antimicrobials, such as trimethoprim-sulfadimidine, and dietary supplements containing polysaccharides. But Banse does not currently recommend antimicrobials because we don’t know what they do to the horse’s microbiome (the resident GI tract microorganisms) and suggests that dietary supplements are likely better for prevention than treatment.

Based on all these studies, Banse recommended veterinarians start horses with mild EGGD lesions (Grade 1 and 2) on 4 mg/kg omeprazole daily, and if there’s no improvement after one month, add sucralfate or misoprostol. She recommended starting horses with more severe lesions (Grade 3 and 4) on the same dose, plus sucralfate or misoprostol, and if there’s no improvement after four to six weeks, change your treatment strategy.

In closing, Banse acknowledged that EGGD is difficult to treat and can take upwards of six to eight weeks to resolve. Before discontinuing treatment have your veterinarian perform gastroscopy. And if the condition doesn’t improve, change or add treatments.