Horses are impressive athletes, but they are also surprisingly prone to sensitive stomachs. A healthy equine stomach is essential for overall well-being, behavior, and performance. When the digestive system becomes unbalanced, it can lead not only to gastric ulcers but also to more serious health complications.
In this article, we take a deep dive into the world of gastric support and explore how different approaches—such as gastric protectants, acid buffers, and acid-blocking medications—can help support a horse’s stomach health. Whether you are looking for a natural equine ulcer supplement or trying to understand how these categories differ, this guide will help you make informed decisions for your horse.
When a horse is diagnosed with gastric ulcers, the first step in treatment typically involves an acid-blocking medication (a proton pump inhibitor), most commonly the well-known omeprazole. But once the acute phase is over, the question becomes: How can you protect your horse’s stomach in the long term?
This is where terms like “gastric protectant,” “stomach soother,” “acid buffer,” and “acid blocker” start showing up again and again.
A stable protective barrier inside the stomach—supported by targeted ingredients—is essential for shielding the sensitive gastric lining from excess acid and helping the tissue heal. For horses that are stressed, ulcer-prone, or already compromised, strengthening these natural defense mechanisms through appropriate feeding strategies becomes especially important.
But what exactly do these categories mean? How do gastric protectants, acid buffers, and acid blockers differ—and when is each one used?
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Because of their unique anatomy and physiology, horses are naturally prone to stomach problems. A horse’s stomach is relatively small and produces gastric acid continuously—acid that is ideally buffered by the bicarbonate found in saliva.
In a natural environment, this system works remarkably well. As grazing animals, horses are designed to eat small amounts of forage around the clock, and their entire digestive tract is still adapted to this steady intake.
Problems arise when human management deviates from this natural pattern, or when a horse develops an especially sensitive stomach due to factors such as underlying health issues, stress, or genetic predisposition.
In these cases, the horse’s natural protective mechanisms are no longer sufficient—and additional support for the stomach becomes necessary, often in the form of a targeted equine ulcer supplement or other types of gastric support.
Acid Blockers:
Correct term: proton pump inhibitors. They significantly reduce—and in many cases almost completely stop—the production of gastric acid.
Acid Buffers:
They neutralize excess acid in the horse’s stomach but do not block acid production. The essential digestive functions of gastric acid remain intact.
Gastric Protectants / Stomach Soothers:
They form a protective layer over the gastric lining, helping shield the stomach wall from direct contact with stomach acid.
To understand which approach works best in different situations, we first need to look at how the equine stomach functions.
Gastric acid is often associated with ulcers in a negative way, but in reality, it is essential for life. Stomach acid breaks down food so nutrients can be absorbed in the intestines. It also reduces the bacterial load in feed, protecting the horse from potentially harmful microorganisms.
In other words: a horse cannot function without gastric acid—long-term suppression is not an option.
However, an excess of gastric acid can quickly become a problem and cause significant discomfort for your horse.
The equine stomach can be divided into two main sections:
Non-glandular (upper) region
The upper portion of the stomach is lined with a non-glandular mucosa, where microbial fermentation takes place.
Glandular (lower) region
The lower portion is lined with glandular tissue that produces pepsin and gastric acid. A thick mucus layer protects this part of the stomach from digesting itself.
Gastric ulcers can occur in both regions—as well as near the pylorus (the stomach exit). Because these areas differ in their structure and natural defenses, both treatment and prevention strategies vary depending on where the ulcer is located.
Unlike humans, horses produce gastric acid continuously, 24 hours a day.
The natural counterpart to this acid is saliva, which is produced during chewing. Saliva is rich in bicarbonate, a natural buffer that helps neutralize stomach acid. Ideally, acid production and saliva production stay in balance.
A horse’s chewing activity—and therefore its saliva production—varies greatly depending on the type of feed. When chewing 1 kg of forage, a horse produces 3–5 liters of saliva, whereas 1 kg of grain results in only 1–1.5 liters.
If a horse consumes large amounts of grain without sufficient chewing, the balance between gastric acid and bicarbonate can be disrupted. Less bicarbonate entering the stomach means the pH drops, making the environment increasingly acidic.
(The pH scale indicates acidity from 1–6, neutral at 7, and alkaline from 8–14.)
During digestion, the pH in the stomach naturally decreases from around 6 to about 3—but insufficient buffering accelerates this drop.
This explains why long periods without forage or feeding grain before hay can be so problematic for horses.
When a horse is worked on an empty stomach—especially at the trot or canter—gastric acid can “splash” upward and come into contact with the sensitive, non-glandular portion of the stomach.
Horses with existing stomach issues often show resistance or discomfort under saddle. For a horse that already has gastric ulcers, acid splash is extremely painful — it is quite literally like “pouring salt into the wound.”
Even in healthy horses, this splashing should be avoided to prevent irritation or injury to the non-glandular stomach lining.
Over-acidification—meaning a stomach environment with a too low pH—can damage the sensitive, non-glandular stomach lining within just 24–48 hours. The result is irritation of the gastric mucosa or the development of gastric ulcers.
Healing depends on the severity, location, and duration of the condition.
Stress can further reduce blood flow to the stomach lining, which in turn increases gastric acid production. A vicious cycle.
Gastric protectants—often referred to as “stomach soothers”—coat the stomach lining with a protective film that shields the tissue from direct acid exposure. These products do not reduce or buffer stomach acid; instead, they give the gastric mucosa time to rest and recover.
Such supplements support the natural defenses of the sensitive stomach lining and help promote the regeneration of gastric tissue.
Flaxseed: Cooked flaxseed is a classic natural gastric protectant. Its mucilages coat the stomach and help protect the gastric lining.
Oats also contain a high amount of these soothing mucilages and are often unfairly criticized in connection with stomach issues.
Supplement feeds based on pectins can also be helpful. Pectins are structural components of plant cell walls and are found in sugar beet pulp, wheat bran, beetroot, apple pomace, and in low-fructan grasses such as timothy and red fescue.
In addition to pectins, the phospholipid lecithin is known for its stomach-soothing properties and supports the natural protective mechanisms of the gastric lining.
An effective gastric protectant for horses typically relies on specific ingredients that help shield the stomach lining. These include mucilages such as pectins, which form a protective layer over the gastric mucosa.
Antioxidants and herbs like Icelandic moss can provide additional anti-inflammatory support.
Unsaturated fatty acids contribute to the overall health and resilience of the gastrointestinal tract.
Attentive readers will have recognized the ingredients mentioned earlier in this article. The well-known, German homemade mixture called “Schlonzi” is a popular natural gastric protectant among horse owners who have the time to prepare it fresh on a regular basis.
The basic recipe is typically made from beet pulp, oats, and oil (usually flaxseed oil), although almost everyone has their own preferred variation. A great addition, for example, is cooked flaxseed.
Unlike gastric protectants, acid buffers do not act directly on the stomach lining. Instead, they neutralize excess gastric acid before it can come into contact with the mucosa.
Acid buffers only target excess stomach acid. They do not block acid production, meaning the acid that is essential for digestion remains available.
There are alkaline, neutral, and acidic solutions. Acid buffers (antacids) are alkaline substances that can neutralize stomach acid by raising the pH level.
Bicarbonate (sodium bicarbonate) produced in a horse’s saliva is an example of a natural acid buffer. However, bicarbonate can also be supplemented through the diet.
Many horse owners use baking soda (a component of baking powder) for this purpose, and there are also numerous commercial equine supplements that contain bicarbonate.
Equine 74 Gastric also belongs to the category of acid buffers. It contains calcium carbonate derived from a specific type of red algae. Thanks to the algae’s honeycomb-like structure, Equine 74 Gastric can absorb excess gastric acid much like a sponge.
This helps maintain a more balanced pH level in the horse’s stomach. It also prevents overly acidic feed from entering the intestines. As a result, the gut microbiome stays more stable, allowing the intestinal microbes to work more efficiently — often leading to improved overall feed utilization.
Good to know: Not all algae are the same, even if their names sound similar. There are important differences in quality and efficacy. We take a closer look at this in our article on Red Algae for Horses.
Bicarbonate has a very short duration of action. It remains in the horse’s stomach for only about 30 minutes.
Equine 74 Gastric, on the other hand, provides buffering for up to 8 hours due to the unique structure of its red algae source. For the best and longest-lasting effect, this supplement is ideally fed morning and evening.
Acid blockers reduce gastric acid production by inhibiting the proton pump. Acid-producing cells, such as the glands in the lower part of the stomach, rely on protons to create stomach acid. When the pumps responsible for transporting these protons are blocked, acid production can be reduced by up to 99%, giving the stomach lining time to heal.
The only proton pump inhibitor approved for use in horses is omeprazole. For treating acute gastric ulcers, this near-complete suppression of acid production is beneficial because it prevents the gastric mucosa from being further irritated.
However, during this period, stomach acid cannot perform its normal digestive functions — including killing bacteria and pathogens present in the feed.
Acid blockers are usually tapered very slowly over an extended period. But is this actually necessary?
Until recently, research assumed that — similar to humans — abruptly stopping a proton pump inhibitor would cause a so-called rebound effect, meaning the stomach would suddenly produce significantly more acid again. This could quickly result in another episode of excess acidity.
When you look at your veterinarian’s treatment plan for gastric ulcers, you will almost always see that omeprazole is gradually reduced over several weeks. The exact recommendation depends on the individual case, of course, but in general, the dosage is decreased slowly over the course of the therapy.
However, early new studies suggest that this rebound effect is far more controversial than previously assumed. A recent 2023 study examined 14 racehorses to determine whether such an effect truly occurs. The horses received daily omeprazole for 57 days.
The researchers hypothesized that gastrin levels would significantly increase during treatment and remain elevated for a longer period after stopping the proton pump inhibitor.
Gastrin is a hormone that stimulates gastric acid production. Under normal conditions, gastrin levels are regulated by the stomach’s pH value.
Omeprazole disrupts this feedback mechanism. During treatment with omeprazole, gastrin levels rise significantly because the body attempts to stimulate more acid production.
In this study, omeprazole was discontinued abruptly after 57 days (no tapering).
During treatment, gastrin levels doubled—but all horses returned to normal gastrin values within 48 hours after stopping the medication.
According to this study, the rebound effect is therefore far shorter than previously believed.
The research team led by Dr. Ben Sykes recommends not tapering omeprazole but instead optimizing that 48-hour window after cessation:
Plenty of turnout and rest — no training, no stress
Unlimited forage (high-quality hay is important)
No NSAIDs or other medications that may irritate the stomach
Acid buffers and gastric protectants can already be used during this period
That said, research on omeprazole and the rebound effect in horses is still in its early stages.
Acid blockers such as omeprazole are prescription medications and should only be used under the guidance of a veterinarian.
In the United States, omeprazole is available over the counter for prevention (Ulcergard), but not for treatment of diagnosed ulcers (Gastrogard).
For prevention, as well as for daily or short-term support of the equine stomach, acid buffers and gastric protectant supplements are generally more effective and appropriate.
Which approach is best for you and your horse should always be discussed with your veterinarian.
For acute gastric ulcers, traditional treatment with an acid blocker is usually necessary. Gastric ulcers are painful and can lead to secondary issues such as colic, so they should never be taken lightly — early treatment is crucial.
After successful therapy, or preventively in horses with sensitive stomachs, gastric protectants and acid buffers can be valuable additions. They serve as supportive measures alongside optimized management and feeding practices, which remain the most important factors in preventing stomach problems.
Sources:
Clark B, Steel C, Vokes J, et al. Evaluation of the effects of medium-term (57-day) omeprazole administration and of omeprazole discontinuation on serum gastrin and serum chromogranin A concentrations in the horse. J Vet Intern Med. 2023; 37(4): 1537-1543. doi:10.1111/jvim.16795
Sykes, B.W. (2021), A free ride: Is long-term omeprazole therapy safe and effective?. Equine Vet Educ, 33: 556-560. https://doi.org/10.1111/eve.13458
Vokes, J.; Lovett, A.; Sykes, B. Equine Gastric Ulcer Syndrome: An Update on Current Knowledge. Animals 2023, 13, 1261. https://doi.org/10.3390/ani13071261
Shan, R.; Steel, C.M.; Sykes, B. The Impact of Two Recommended Withholding Periods for Omeprazole and the Use of a Nutraceutical Supplement on Recurrence of Equine Gastric Ulcer Syndrome in Thoroughbred Racehorses. Animals 2023, 13, 1823. https://doi.org/10.3390/ani13111823
Further reading
Read more about equine gastric ulcers — what they are, how they form, how to treat them, and how to prevent them.