Gastric ulcer syndrome (GUS) is an overriding term for two anatomically distinct types of gastric ulcers: equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD). Because they occur in two different parts of the equine stomach, these lesions differ not only in their pathophysiology but also in their treatment and management approaches. Let’s review existing and emerging nutritional recommendations for preventing both ESGD and EGGD.
Our Current Knowledge About EGUS Prevention
In general, management is key to both prevention and treatment. According to a recent overview of GUS, dietary management is a strategy of major importance. The authors discussed common-sense feeding recommendations and the most significant factors for GUS prevention: roughage, exercise, and the diet’s nonstructural carbohydrate (NSC) content.1
Historically, we believed offering horses free-choice forage was the primary strategy to use for ESGD prevention. As time went on, this strategy showed inconsistent results, in part because of “a circadian rhythm of foraging and inconsistent effects of pasture on ESGD.” Most horses consume the bulk of their forage intake during daylight hours. Just offering free-choice hay doesn’t mean a horse will consume a sufficient amount; the owner might need to measure exactly how much the horse eats. For horses that aren’t dealing with obesity issues, the recommendation is to provide forage in the amount of 2% of their body weight per day.
Feeding hay prior to exercise has a buffering effect, with as little as 300 grams of hay protecting against ESGD. Feeding and duration of exercise are not as critical when it comes to preventing EGGD; rather, horses should receive two to three full rest days each week.
A low-NSC diet with the bulk of it fed as forage is considered a good strategy for all equine nutritional plans. Study results show that low-NSC diets and reduced dietary starch can help lower ESGD and EGGD incidence.
Vegetable oil supplementation is invaluable for providing calories to substitute for high-NSC supplements. Dietary oil is beneficial for managing EGGD but has little effect on lesion healing for ESGD. Feeding polyunsaturated fatty acids (PUFAs) helps regulate systemic inflammation, particularly for EGGD prevention and management. Omega-3 fatty acids (fish-oil based) are beneficial for reducing inflammation; in contrast, omega-6 fatty acids (corn oil) might amplify inflammation.
Trials with pectin-lecithin supplements such as beet pulp show encouraging results for reducing the risk of ESGD and improving both ESGD and EGGD. This dietary supplement works best when a horse is not faced with intermittent fasting.
Multiple studies have examined the use of a variety of nutraceutical supplements to prevent GUS:
- In two studies without controls, horses in high-level training were supplemented with licorice root extract, magnesium hydroxide, calcium carbonate, and aloe vera. They experienced fewer and less serious squamous and glandular lesions over 30 days.
- A micronized soy product showed some protection against ESGD.
- A rice extract seemed beneficial for reducing ESGD scores and lesion healing.
- Sea buckthorn berries showed some protection against worsening of EGGD but not ESGD.
- Hyaluronan and schizophyllan improved preexisting ESGD and EGGD lesions.
While these ingredients provide a hopeful look at options for managing GUS, the authors note: “Many of the nutraceutical studies do not account for variabilities in feeding and management changes in different populations.” Further, nonclinical models of disease might not be relevant for multifactorial-related clinical disease.
Take-Home Message for Veterinarians: It is most important to focus on dietary management of gastric disease and use nutraceuticals only as an adjunct to comprehensive management practices. The authors of this review study counsel caution when attempting to extrapolate results from other species or from studies that are not evidence-based or lack controls.
The Impact of High Sugar and Starch and Low Roughage and Meal Frequency on GUS
The equine digestive system evolved to intake small portions of forage with frequent browsing and grazing. In response, gastric acid secretion is relatively continuous. With fasting, strong acid levels collect in the stomach. Researchers in Denmark recently evaluated the impact of low forage intake coupled with high NSC intake.2
Horses in intense exercise (e.g., galloping) might be affected by gastric acid contacting the nonglandular mucosa. Forage in the stomach provides protection against this “splash effect.” Frequent meals that cumulatively provide 1.5-2% of a horse’s body weight help mitigate this gastric ulceration risk. Food intake and chewing also stimulate saliva production, which further buffers stomach pH. Feeding only a couple of meals a day with fasting of more than six hours in between increases a horse’s risk of developing GUS.
This study also reviewed the effects of a low-forage diet, which increased the number of ulcerative lesions compared to controls. Not only did saliva production decrease, but gastric juices had greater chance of contacting the squamous mucosa, especially during exercise. In contrast, horses fed free-choice forage (hay and/or pasture) develop higher pH in their stomachs due to continuous saliva flow and the presence of forage in the stomach. Alfalfa’s high calcium and protein content further buffers stomach acid to protect the squamous mucosa.
The authors noted that despite sufficient forage, if a horse consumes a high-sugar and -starch supplement of more than 1 g/kg body weight per meal, the forage component might not be as protective against the development of ulcerative lesions. Starch digestion produces lactic acid and has adverse effects on the integrity of the stomach mucosa.
A potentially useful therapy that has not yet been studied in horses is a potassium-competitive acid blocker (PCAB) that might negate the need for proton pump inhibitors like omeprazole. This drug binds reversibly to potassium-binding sites to block acid production from parietal cells better than proton pump inhibitors do. It can be administered to fed or fasted horses.
Take-Home Message for Veterinarians: To prevent ESGD, feed forage at a minimum of 1% body weight per day (preferably far more) and maintain sugar and starch intake at less than 2 g/kg/meal (less than 2 pounds per meal). Forage fed at ≥ 2% of body weight does not protect against ESGD when horses are also consuming high-sugar and -starch supplements with each meal.
Dietary recommendations for preventing equine gastric ulcer disease center around a high-fiber and low-starch diet. This strategy is also important for management following cessation of pharmaceutical treatment with proton pump inhibitors.
References
- Vokes J, Lovett A, Sykes B. Equine Gastric Ulcer Syndrome: An Update on Current Knowledge. Animals 2023, 13, 1261. DOI: 10.3390/ani13071261
- Galinelli N, WAmbacq W, Broeckx BJG, et al. High intake of sugars and starch, low number of meals and low roughage intake are associated with Equine Gastric Ulcer Syndrome in a Belgian cohort. J Anim Physiol Anim Nutr 2021, vol 105 (Supplement 2), pp. 18 – 23; DOI: 10.1111/jpn.13215
Sentinel offers low-NSC feed options to help prevent EGUS, plus Sentinel Care Gastric Support, a supplement designed to maintain a healthy gastrointestinal environment.
This article originally appeared in “Feeding for the Future: Nutrition Knowledge for the Modern Equine Practitioner,” brought to you by Sentinel Horse Feeds. You can download the complete issue here.
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