Dealing with equine gastric ulcer syndrome (EGUS) can leave owners with more questions than answers. And they’re not alone—it turns out veterinarians have questions about EGUS, too.
As a remedy, vets participated in a question-and-answer format Table Topic on managing EGUS during the 2018 American Association of Equine Practitioners convention, held Dec. 1-5 in San Francisco, California. Frank Andrews, DVM, Dipl. ACVIM, director of the Equine Health Studies Program and clinical medicine service chief at Louisiana State University School of Veterinary Medicine, in Baton Rouge, and Sarah Reuss, VMD, Dipl. ACVIM, a veterinary specialist with Boehringer Ingelheim Animal Health, co-moderated the discussion.
Equine gastric ulcer syndrome collectively refers to ulcers or erosions in either the squamous (upper) or glandular (lower) regions of the horse’s stomach. These painful lesions have been identified in a high number of horses, particularly those in intense training and competition, and a variety of dietary and management factors can make them worse. Gastric ulcers can cause performance issues and ill-thrift and might signal the need for husbandry changes. They also warrant aggressive treatment and management.
The U.S. Food and Drug Administration (FDA) has approved two doses of a paste omeprazole (designed to decrease the stomach’s acidity) for EGUS in horses. The first, administered at 4 mg/kg per day for 28 days is for treatment and the second, 1 mg/kg per day, is for prevention as needed during periods of increased stress. Recommended management changes include a forage-first, low-grain diet, ample turnout, avoiding certain anti-inflammatory drugs, and stress management.
What are the chances of ulcer recurrence after treatment, and how do we avoid it?
Studies have confirmed omeprazole paste is a successful treatment option for EGUS. Those positive results led to FDA approval for treating equine gastric ulcers and preventing their recurrence. However, as many equine practitioners are aware, after 28 days of treatment, ulcers can recur quickly without concurrent management chances—within three to five days in some cases.
“The 2 mg/kg dose helps prevent recurrence, suggesting that chronic cases should be treated long-term,” said Andrews. “Horses more likely to require ongoing treatment are those kept in training and offered less-than-ideal diets.”
Because the ultimate goal is to keep horses in training, and considering that omeprazole treatment is costly, he recommended combining medication and management changes for best results.
How long should the horse be treated?
This varies depending on whether the ulcer occurs in the glandular or squamous portion of the stomach. Despite both being included in EGUS terminology, experts believe these should be considered two distinct diseases.
“I recommend endoscopy of the stomach to assess response to therapy in all horses, usually at the end of the first month of treatment,” said Andrews. “Do not rely simply on resolution of clinical signs.”
Glandular ulcers can be particularly troublesome to overcome, often necessitating the administration of a combination of omeprazole and sucralfate (a medication that coats and protects the ulcer to allow it to heal).
“These horses will need to undergo gastric endoscopy again in four to six weeks, and the ulcer(s) still may not be healed, so it’s important to properly prepare owners for this outcome,” Andrews said.
Some affected horses (excluding pregnant mares) benefit from also receiving the medication misoprostol. This synthetic prostaglandin helps stimulate the delicate lining of the gastrointestinal tract to heal.
Attendees also discussed protocols for optimal gastroscopy, which include:
- Fasting the horse from feed for 12 to 16 hours prior to scoping, but only remove water from the stall or enclosure two to four hours before scoping;
- Giving omeprazole on the morning of the exam if the horse is currently being treated; and
- Obtaining a sample of the horse’s gastric juices to measure pH. If the horse is receiving and effectively responding to omeprazole, the pH should be between 4 and 7. If the pH is less than 4 within two to 12 hours of omeprazole administration, than the horse is considered a nonresponder. In this scenario, the veterinarian should alter the drug dose, administration timing, etc. If the pH is appropriate (above 4) and the ulcer persists, the vet should investigate why the mucosa isn’t healing appropriately.
When discontinuing treatment, do you need to taper off the ulcer medication?
No data currently exist to clearly answer this question. Many of the veterinarians in attendance, however, said they recommend tapering, even if only to make owners more diligent in implementing the dietary and low-stress management recommended for affected horses.
When is the best time of day to give horses an oral anti-ulcer medication?
If a horse has squamous ulcers, timing of dosing might not be particularly important. However, for horses with glandular disease or those that don’t absorb omeprazole well, the moderators recommended administering it in the morning before a horse trains or eats (at least one hour before eating).
“Omeprazole, despite being a good product, actually has poor bioavailability—only 14-16% is absorbed systemically—and is maximally effective about one hour following administration,” said Andrews.
Andrews and Reuss recommended:
- Administering omeprazole before feeding in the morning;
- Offering a hay meal to distend the stomach—which will activate the acid-producing cells in the stomach that the omeprazole molecules will hunt down and turn off to decrease acid production—about 1 to 1 1/2 hours later;
- Always feeding grain or concentrate feeds about an hour after hay to take advantage of the forage’s buffering action; and
- Administering sucralfate separately about 1.5 hours after the omeprazole, as it can negatively affect the absorption of omeprazole.
Will any noncommercial products help horses with ulcers?
There’s no way around it: Gastric ulcers are expensive to treat. So, many owners look for alternative ways to more economically treat ulcers rather than using FDA-approved products and having horses scoped before, during, and after treatment.
Reuss said owners and their veterinarians can easily obtain compounded omeprazole; however, poor-quality products are prevalent, with only two out of 10 tested compounded products containing >80% of the expected omeprazole (indicated on the product label) within 30-90 days of syringe storage.
Omeprazole needs to be protected from acid degradation in the stomach to reach the small intestine, where it gets taken up by the bloodstream to affect the acid pumps, she said. This is why unprotected forms of omeprazole don’t allow ulcer healing. It’s also important to remember that unless veterinarians are scoping horses to monitor response to treatment, less-than-ideal products might have enough effect to mask clinical signs but aren’t effective enough to allow true healing of ulcers, Reuss added.
A variety of nutritional supplements abound with labels claiming the products support horses with gastric ulcers. These include various ingredients, such as pectin, lecithin, aloe vera, probiotics, hydrolyzed collagen, and sea buckthorn berry, among others. Limited data support some of these (pectin, lecithin, sea buckthorn berry, hydrolyzed collagen) so Reuss and Andrews recommended looking for those research-supported ingredients on any supplement label. They also suggested factoring in their costs; some might add up to even more than the appropriate FDA-approved pharmacologic agents.
Both mediators agreed that owners shouldn’t waste their money trying to save money. Treat these horses with strategies proven to be effective.