Feeding Management Strategies for Horses with Gastric Ulcers

Robert Jacobs , Ph.D.

Research Manager, Equine Innovation

Gastric ulceration in the horse is a highly prevalent, yet often difficult to manage condition. The development of gastric ulcers is a function of multiple factors including breed, exercise level, diet, and management. Because of the multi-factorial nature of this disease state, a multi-faceted approach including medical treatment, management changes, and nutritional intervention is necessary to best support horses with gastric ulcers. Dietary management is critical in reducing the risk of developing gastric ulcers and supporting optimal gastric health. 

Equine Gastric Ulcer Syndrome (EGUS) is a highly prevalent condition in most classes of horses. Recently, EGUS was further differentiated into Equine Squamous Gastric Disease (ESGD), and Equine Glandular Gastric Disease (EGGD) highlighting the locations of the lesions in the various regions of the horses’ stomach. ESGD and EGGD are likely caused by a different combination of factors, and dietary management strategies are primarily focused on supporting horses with ESGD. As a non-ruminant herbivore, the horse evolved to ingest a diet made up primarily of high fiber forage throughout the day. Modern management practices, in which horses are meal-fed calorically dense diets high in starch with prolonged periods of fasting, have been attributed to increased risk of gastric ulceration. When dealing with suspected cases of gastric ulceration in horses, recognition of risk factors and symptoms, diagnosis via imaging, treatment utilizing approved pharmaceuticals, and changes to management and nutrition are the critical steps in caring for these horses.

Nutritional management of gastric ulceration can be categorized into these main areas including:
  1. Reduction of fasting periods
  2. Proper forage selection
  3. Appropriate feed selection
  4. Supplements

Reduction of Fasting Periods

Horses secrete gastric acids continually during the course of the day. Natural buffers to this acid secretion include bicarbonate incorporated into the saliva that horses produce only in response to feed being chewed, and the feedstuffs themselves that are consumed. During periods of fasting, the pH of the equine stomach falls below a pH of 4.0, and routinely lower, around a pH of 2.0. This persistent low pH in the gastric environment results in stress on the gastric mucosa, specifically that of the non-glandular portion of the horse’s stomach. Ensuring horses have access to feedstuffs throughout the day increases the amount of time that the stomach remains at a pH above 4.0, which has been identified as a level below which increases the risk of gastric ulceration. This can be accomplished by offering horses access to pasture or hay multiple times throughout the day. Other methods to prolong consumption time include the use of slow-feed hay nets and spreading hay out around a pasture or dry-lot. Providing small, frequent concentrate meals is another method that can be used to reduce the fasting periods during a given day.

Proper Forage Selection

As stated previously, providing access to forage is critical in reducing the chances of a horse developing gastric ulcers. However, selecting the proper forage is important. Free-choice access to hay and/or pasture may result in overconsumption which can predispose them to other conditions such as obesity, laminitis, or endocrine disruption. Pasture and hay analysis allow you to understand the nutritional contribution of the forage and aid in the selection of the appropriate source. Alfalfa forage has been shown to be efficacious in raising the pH of the horses’ stomach and reducing the prevalence of gastric ulceration. Incorporating alfalfa forage in the form of long stem hay, cubes, or pellets can help horses that may be predisposed to gastric ulceration. However, abrupt forage changes such as the offering of alfalfa only during travel should be avoided due to the risk of colic or other gastrointestinal challenges.

Appropriate Feed Selection

Concentrate diets are an ideal source of nutrients that are necessary to complement the forage component of a horse’s diet. Diets very high in non-structural carbohydrates (NSC) have been associated with an increased risk of EGUS. Diets should not exceed 2 g/kg BW of starch per day or 1 g/kg BW of starch per meal for horses at risk of gastric ulceration. As a reference, a 4 lb meal of Purina® Strategy® GX contains 454 g of NSC, well below the threshold for a 1200 lb horse. Diets in which calories are derived from fat and fiber rather than starch and sugar such as Purina® Strategy® Healthy Edge®, Purina® Ultium® Competition, and Purina® Ultium® Gastric Care are other options for these horses. Regardless of feed selection, offering small, frequent meals reduces the periods of fasting, while also limiting the amount of NSC fed at any given time.


Dietary supplements aimed at supporting gastric health are plentiful. Purina® Outlast® Gastric Support Supplement is a gastric support supplement that has been extensively researched in multiple research trials. Purina® Outlast® Gastric Support Supplement contains a unique seaweed-derived calcium source that effectively buffers the gastric environment for a prolonged period of time. As a stand-alone supplement it is recommended to offer Purina® Outlast® Gastric Support Supplement 2-3 times daily. For a 1000 lb horse, a 200 g serving will provide 2-4 hours of support. Purina® Outlast® Gastric Support Supplement is also incorporated into many of the premium Purina equine feeds including the entire Purina® Omolene® family of feeds, Strategy® GX, Strategy® Healthy Edge®, and the Purina® Ultium® family of feeds. Providing a 4 lb feeding of any of these products will provide a full serving of the Purina® Outlast® Gastric Support Supplement. If smaller feeding rates are desired, topdressing with the Purina® Outlast® Gastric Support Supplement can provide the desired effect. Purina® Outlast® Gastric Support Supplement is also incorporated into Purina® Outlast® Horse Treats for easy feeding.
Electrolyte supplementation is another area of importance related to gastric ulceration. Supplementation with paste or other orally delivered forms of electrolytes have been correlated with increased gastric ulceration especially when offered without feed. It is recommended that for horses that require supplemental electrolytes, that they be offered with or mixed in feed. Further addition of electrolytes to water has been shown to decrease voluntary water intake, which is another risk factor in gastric ulceration.


Ensuring horses have access to appropriate forage throughout the day will help to reduce the fasting period associated with increased gastric ulceration. Selecting the appropriate feed for individual horses, such as those with reduced starch and sugar, and providing small frequent meals, can ensure that the horse receives the nutrition that it requires without increasing the risk of gastric ulceration. Supplemental electrolytes should be offered to horses in combination with feedstuffs to reduce the risk of gastric ulceration associated with electrolyte supplementation on an empty stomach. Supplementing with Purina® Outlast® Gastric Support Supplement or providing feeds with this supplement incorporated provide prolonged support to the gastric environment.
JEVS Abstract: Feeding a Seaweed-Derived calcium source vs. calcium carbonate on physiological parameters of horses. JEVS, 2019.
JEVS Abstract: The Effect of a Natural-Source Mineral Supplement on Gastric Ulceration in Horses. JEVS, 2017.
JEVS Abstract: Feeding Natural Source Minerals or Calcium Carbonate to Horses: Is there a Relationship to TCO2? JEVS, 2017.
JEVS Abstract: The Effect of a Natural Source Mineral Supplement on Gastric Juice pH in Horses. JEVS, 2017.

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