Equine supplements targeted towards ulcer prevention are on the rise, but not all products are created equal.
Dietary management for horses with ulcers can include increasing forage and decreasing grain, as well as providing supplements that support a healthy digestive tract.
While there are many safe and natural ingredients that can support the healing of the gastrointestinal tract, some purported anti-ulcer supplements lack research to validate their efficacy.
Other ingredients (like antacid supplements for horses) will only temporarily mask the effects of ulcers while working against the horse’s natural physiology.
These supplements can interfere with digestive processes and are more likely to be associated with acid rebound and recurrence of ulcers.
If you suspect your horse has ulcers, consult with a veterinarian to understand your treatment options before adding supplements to your horse’s diet.
Gastric ulcers are a pain in the GUT. Choosing a supplement for them doesn’t have to be!
Here we review the top 16 most popular supplements currently available to reduce the risk of ulcers and improve overall gut health in your horse.
An Overview of Equine Ulcers
Equine ulcers are open sores or lesions that can develop throughout the gastrointestinal tract of your horse.
Ulcers most commonly occur in the stomach, hence the name gastric ulcers. The upper squamous region of the stomach is most at risk of ulceration. 
This area has the greatest exposure to stomach acids and lacks the defenses present in other parts of the stomach.
Mucous and bicarbonate produced in the glandular region of the stomach act as a buffer to the acidic environment.
The squamous region cannot produce mucous and does not have a similar defensive strategy. Instead, the squamous region relies on food and saliva to form a buffer against acids.
Medications for Ulcer Treatment
Drug therapies are commonly used to treat equine ulcers. Available drugs include omeprazole, ranitidine, and cimetidine.
These drug therapies can be effective for treating ulcers, although they are not without side effects. 
Drug therapies act to inhibit the secretion of gastric acids. Reducing acid secretion can increase stomach pH and allows the ulcers to heal.
However, ulcer rebound after treatment with drug therapies is common in horses. Once treatment stops, the stomach responds with an over-production of acid.
This phenomenon is known as rebound acid hypersecretion (RAH) and it results in an unnaturally low pH. This highly acidic environment can cause new ulcers to form. 
Given the risk of rebound and side effects with medications commonly prescribed to treat gastric ulcers, many horse owners seek natural alternatives.
Supplements for equine ulcers can work in different ways that may be beneficial in preventing ulcers. When supplemented alongside treatments with drugs, they may also function to minimize ulcer rebound.
Here we provide a summary of the purported mechanisms of action of 16 popular supplements for equine ulcers. We also rate the efficacy of these supplements based on the current research and available clinical trials.
As always, it is recommended to consult with an equine nutritionist before making dietary changes. Mad Barn offers a complementary evaluation and individualized recommendations for your horse when you submit your horse’s diet online.
Top 16 Supplements for Ulcers in Horses
Visceral+ by Mad Barn is an all-in-one supplement for horses with ulcers that has been clinically studied and proven to work.
Visceral+ was developed in conjunction with equine veterinarians who were frustrated with the frequency of ulcer rebound when using conventional drug therapies.
They saw a need for a supplement to help horses being treated with GastroGard (omeprazole) and UlcerGard to minimize the risk of relapse post-treatment.
Visceral+ is designed to support the function of the immune system and maintain stomach and hindgut health. It works with the horse’s natural biology to support the intestinal barrier that protects stomach tissue from ulceration.
Mad Barn’s Visceral+ formula combines multiple trusted ingredients for gastric ulcers including:
- Saccharomyces cerevisiae – a specific strain of yeast developed to support digestive health
- 20 billion CFUs of a 5-strain probiotic blend
- Dietary Oils
- Marshmallow Root Extract
- Meadow Sweet
- Slippery Elm Bark
Combining multiple ingredients into one holistic product is likely more beneficial than using single supplements. These components achieve different modes of action and could provide a synergistic or enhanced effect.
Proposed Mechanism of Action
- Supports the mucosal layer of the gastrointestinal tract by supporting normal mucin production
- Supports healing of epithelial cells
- Promoting digestive comfort to minimize stress
- Supporting normal defenses against pathogens by helping to maintain immune health
- Nourishing the equine microbiome with high-CFU supplementation of probiotics
- Anti-inflammatory and antioxidant effects to minimize pain and discomfort
Visceral+ is formulated to address the high prevalence of ulcer rebound after treatment with omeprazole.
In a clinical trial on Standardbred horses with gastric ulcers, horses were treated with omeprazole for 15 – 30 days and Visceral+ for an additional 30 days.
Feeding Visceral+ at 80 g per day resulted in significant improvement and healing of ulcers in these horses.
Additionally, Visceral+ has been shown to support gastric health without the use of omeprazole.
THE VERDICT: Suitable evidence of efficacy in horses with ulcers.
2) Pectin-Lecithin Complex
Lecithin is a general term for a type of phospholipid found in plants.
Phospholipids, including phosphatidylcholine and phosphatidylserine, are important fatty-acid-containing compounds that form cell membranes and have other important physiological roles.
Lecithin is commonly derived from soybeans to be used in supplements.
Pectin is a sugar known as a polysaccharide found in fruits and vegetables. Pectin is a type of fibre with prebiotic benefits.
Research shows that lecithin and pectin can help to protect the gastrointestinal tract from damage caused by high acidity.
Proposed Mechanism of Action:
- Forms a barrier within the gastrointestinal tract to protect cells of the intestinal lining from stomach acid
- Increases digestibility of fats prior to entering the hindgut which reduces acid production from fermentation
- Pectins form a gel by binding to bile acids, preventing them from causing damage
In a seven-day study of 8 ponies undergoing periodic food deprivation, administering a 250 g pectin-lecithin supplement daily did not prevent ulcers from forming. 
In another study over a longer duration of four weeks, mares fed hay and concentrate for two hours daily were given a pectin-lecithin supplement at 50 g per 100 kg of body weight. This is approximately equivalent to 250 g per day. 
After four weeks, the researchers induced ulcers by depriving the horses of food. The supplementation protocol did not protect against the formation of ulcers or gastric lesions.
In a different study, researchers fed the same pectin-lecithin supplement to horses affected by gastric lesions. The supplement was fed at a dosage of 300 grams three times per day.
Supplementation with the pectin-lecithin complex resulted in improved lesion severity. 
Another study examined the effects of this supplement on ten racehorses with differing levels of ulcer severity.  The horses were fed 50 g per 100 kg of body weight (approximately 250 grams) over 30 days.
Horses fed lecithin and pectin exhibited significantly decreased ulcer severity after the treatment period. Three of the ten horses had complete healing of gastric ulcers after supplementation.
This study did not include a control group, but it does support the efficacy of pectin-lecithin for helping to heal gastric ulceration.
Overall, this supplement might not prevent ulcers from forming but could promote the healing of lesions in stomach tissue. More research is needed to determine an optimal dose.
THE VERDICT : Suitable evidence of efficacy for healing ulcers. Ineffective for preventing gastric ulcers.
Glycine is a conditionally essential amino acid used to make proteins in the body.
Glycine is considered conditionally essential because the requirements for this amino acid are usually met by endogenous production within the horse’s body. Under most circumstances, horses can produce enough of this compound to not require it in the diet.
However, extra glycine may be beneficial during times of high demand such as during ulcer healing when there is rapid tissue turnover. This amino acid becomes essential during periods of rapid growth or healing.
Glycine has many functions in the body. It is used to build collagen and muscle tissue.  It is also necessary for the synthesis of other amino acids, glutathione, creatine, DNA and more.
Glycine is also involved in maintaining tissues that form the lining of the gastrointestinal tract as well as the production of bile salts and digestive enzymes.
Research shows that glycine is necessary to maintain the integrity of the intestinal mucosa – a mucous membrane that lines the intestinal wall. Glycine supplementation could provide additional benefits to your horse along with supporting gastric health.
Proposed Mechanism of Action
- Involved in antioxidant reactions and increases the antioxidant capacity of cells
- Enhances protein synthesis to reduce tissue damage and improve wound healing
- Supports intestinal barrier function by maintaining gastric mucosa
- Inhibits the secretion of stomach acid
- Protects the mucosa from chemically and stress-induced ulcers
In other species, such as humans and pigs, glycine supplementation is known to reduce wound severity, support tissue repair, and support the immune system. 
In rats, glycine supplementation reduced severity, number, and size of gastric ulcers.  This study used a glycine dosage of between 25 to 35 mg per kg body weight, which is equivalent to 12 to 17 grams for a 500 kg horse.
In this study, there was no effect of glycine on the secretion of stomach acids, but other studies have found different results.
In another study, glycine was found to protect against alcohol-induced ulcers in rats.  The researchers propose that it exerts a gastroprotective effect by acting as a free-radical scavenger or antioxidant.
In horses, there are few studies evaluating the effects of glycine supplements on gastric ulcers. However, there are studies involving administering glycine along with other anti-ulcer ingredients.
A pelleted supplement containing several ingredients, including glycine, was found to prevent more severe ulcers in the squamous region of horses. 
Horses in this study were stall confined for six weeks. Researchers fed the horses a high-grain diet with or without the pelleted supplement mixed into their feed.
The supplemented group appeared to be protected from the recurrence of ulcers in the squamous region after gastric ulcer treatment.
Mad Barn’s Visceral+ supplement contains Dietary Escape Microbial Protein (EMP™) which is digested in the small intestine and provides glycine as well as other amino acids that make proteins to support tissue repair.
While there are only a few studies examining the effects of glycine on ulcers in horses, benefits are well-documented in other species for reducing ulcer severity. The direct effects of glycine in horses should be further investigated.
THE VERDICT Some evidence of efficacy for reducing ulcer severity. More research is warranted to understand effects of glycine in isolation on equine gastric ulcers.
Glutamine is another non-essential amino acid involved in tissue building and repair.
However, glutamine becomes conditionally essential during periods of stress or illness. Glutamine levels in the horse’s body can become depleted quickly in times of high stress such as intensive training or travel.
Horses prone to ulcers during competition season might benefit from supplementation as their glutamine requirements are higher when competing.
Glutamine may counteract the negative effects of NSAIDs on the digestive system. Long-term use of nonsteroidal anti-inflammatory drugs is known to damage the intestinal barrier and increase the risk of ulceration.
Research shows that NSAIDs increase gut permeability, potentially leading to a condition known as Leaky Gut Syndrome.
When the gut barrier function is impaired, toxins and bacterial products may be absorbed into the body. This can cause an immune response and inflammation of the gastrointestinal tract, known as colitis. 
Glutamine supplementation may help to prevent this increase in gut permeability.
Proposed Mechanism of Action
- Promotes the building and repair of tissues
- Is a major source of energy for cells lining the gut
In a study in humans, NSAIDs were found to increase intestinal permeability. This effect was partially blocked when glutamine was supplemented at the same time. 
In rats with colitis, glutamine reduced pro-inflammatory gene expression. It may help to reduce the overall amount of inflammation in the intestinal tract of rats affected by colitis. 
In this study, glutamine was fed at a rate of 25 mg per kg of bodyweight per day for seven days. This serving size is equivalent to 12 grams for a 500 kg horse per day.
After treatment with glutamine, the researchers saw significant reductions in damage throughout the digestive tract.
An in vitro study examining colon tissue from euthanized horses found that glutamine improved mucous composition. This suggests that it support intestinal mucus barrier function. 
The colons from these horses were subjected to inflammatory factors and NSAIDs to increase permeability and induce damage. Administering glutamine improved the recovery of the colon.
Although this amino acid has not been extensively studied in horses, it is well known that glutamine is one of the main energy sources for cells of the digestive tract.
Providing adequate levels of this amino acid supports these cells and the maintenance of adequate mucosal production to protect against damage by stomach acids.
Glutamine is an ingredient in Mad Barn’s Visceral+ supplement.
THE VERDICT: Strong evidence of efficacy for ulcers.
Yeast are single-cell organisms that naturally populate the digestive tract of horses. Equine supplements most commonly use yeast from the Saccharomyces genus, of which there are several species.
Saccharomyces cerevisaie and Saccharomyces boulardii are two well-researched species of yeast that have a long list of documented benefits for immune and digestive health.
Yeast has a probiotic effect when consumed by horses. Yeast support hindgut function in horses by improving fibre digestion, stabilizing hindgut pH and improving nutrient absorption.
Proposed Mechanism of Action:
- Increases gastric fluid pH levels
- Improves nutrient digestibility
- Reduces volatile acid production
While there is an abundance of research on the use of Saccharomyces for overall digestive health in horses, there is limited information on its efficacy for gastric ulcers.
The available studies looking at the effects of Saccharomyces yeast on equine ulcers have used supplements with a combination of other ingredients, making it difficult to know what role yeast played in the results.
In 2014, a study of Thoroughbred racehorses undergoing high-intensity exercise looked at the effects of Saccharomyces cerevisiae along with a pectin-lecithin complex and magnesium hydroxide as an antacid.
2 grams of yeast were fed alongside 95 g of the pectin-lecithin complex and 20 g of magnesium hydroxide. 
This supplement combination did not reduce the severity of ulcers. However, it did reduce the odds of developing more severe ulcers after high-intensity exercise.
In another equine study, researchers fed horses a high-starch diet to intentionally lower hindgut pH levels. This diet made the hindgut more acidic.
Excessive acidity in the hindgut (known as hindgut acidosis) is a risk factor for hindgut ulcers.
Yeast supplementation stabilized pH levels in these horses by reducing acid concentrations in the hindgut.  This suggests a potential benefit for reducing hindgut ulcers.
There is significant evidence of efficacy for using yeast supplementation to promote digestive function and gut health. But more research is needed to understand potential benefits for gastric ulcers.
The Verdict: Some evidence of efficacy in horses. More research is required with a focus on gastric ulcers.
6) Slippery Elm
Slippery elm bark is obtained from the American Elm plant. Slippery elm is thought to soothe irritations of the digestive tract and support the healing of ulcers.
This natural plant extract may be beneficial because it has high mucilage content, as well as high calcium, flavonoid, and vitamin content.
Proposed Mechanism of Action
- Soluble fibre content delays gastric emptying, keeping the stomach full for longer
- Anti-inflammatory properties
- Supports mucous barrier function
- Acts as a prebiotic, supporting the growth of beneficial probiotic microorganisms within the digestive tract
In humans with gastric irritation, supplementation with slippery elm resulted in improved symptoms based on a self-evaluation. 
A large observational study in horses demonstrated significant benefits of mucilage from slippery elm for ulcers. 
Four days of slippery elm supplementation in 198 horses with ulcer-related colic resulted in improvements for 85% of horses.
In this study, 23 horses experiencing gastric ulcers saw complete ulcer healing with the use of the slippery elm supplement. These results were observed without the use of other treatments.
Slippery elm bark appears to improve the mucous barrier and reduce gastric irritation.
THE VERDICT: Moderatae evidence of efficacy for equine gastric ulcers.
7) Marshmallow Root Extract
Marshmallow root extract is used to relieve irritation and inflammation in the respiratory system and help soothe the digestive tract.
Marshmallow (Althea officinalis) has a long history of use as a digestive remedy. The roots of this herb contain high levels of polysaccharides that form mucilage as well as flavonoids that support healthy cells.
Proposed Mechanism of Action
- Polysaccharides bind to mucous membranes to soothe irritated cells of the gastrointestinal tract
- Antioxidant and anti-histamine effects can support healthy cells lining the digestive tract
Marshmallow root extract has not been extensively studied in horses. In other animals, including humans, marshmallow root extract is used to support mucous membranes of the respiratory and digestive systems.
Feeding rats marshmallow flower extract for 14 days before experimentally disrupting the gastric environment decreased the number and severity of gastric ulcers. There was a significant decrease in oxidative stress and inflammatory histamine release. 
An in vitro study demonstrated that marshmallow root extract can support healthy gut cells by forming a protective layer. These results suggest that marshmallow extract facilitates healing in the tissue below this protective layer. 
THE VERDICT: Some evidence of efficacy for gastric ulcers in other species. More research is needed in horses.
Meadowsweet (Filipendula ulmaria) is a natural source of salicylic acid, the active ingredient in aspirin.
It is commonly used in traditional medicine as an anti-fever, anti-inflammatory and pain relief supplement.
Meadowsweet plant products are given to horses with arthritis and digestive problems like indigestion, heartburn, and gastric ulcers.
Proposed Mechanism of Action
- Tannins in meadowsweet are thought to protect the gastric mucosa and reduce irritation in the intestine
- Salicylates have anti-inflammatory and pain relieving effects
No research on meadowsweet and gastric ulcers has been performed in horses.
It is primarily added to gut health supplements for pain relief associated with ulcers and intestinal irritation. It may support comfort and help the animal resume normal behaviours more quickly and increase feed intake.
THE VERDICT: Some evidence for minimizing gastric ulcers in other species. More research is needed in horses.
9) Aloe Vera
The aloe vera plant is a perennial succulent that produces aloe vera gel. The gel is used medicinally for its anti-inflammatory properties.
The bioactive components include polysaccharides, anthraquinones, and salicylic acid.  Aloe vera is also a source of many vitamins, minerals, and amino acids.
Aloe vera juice has been used to treat digestive ailments in humans for many years and there is good evidence that it works.
Proposed Mechanism of Action
- May inhibit pro-inflammatory mediators, specifically prostaglandin E2 and interleukin 6
- Acts as an antioxidant to reduce oxidative stress in the gastrointestinal tract
- Improves the integrity of the mucous barrier due to its glycoprotein content
- May help regulate gastric acid secretions
Ulcerative colitis is an Inflammatory Bowel Disease (IBD) in which ulcers develop in the large intestine (colon).
In humans with ulcerative colitis, the effects of aloe vera gel were compared to a placebo for clinical remission, improvement, and response.
The majority of patients who consumed 100 ml of aloe vera gel twice daily for four weeks experienced benefits on all three variables compared to the placebo-control group.
In horses with gastric ulcers, feeding aloe vera improved the severity of lesions in the squamous region of the stomach.
Forty horses with squamous and/or glandular lesions were either supplemented with aloe vera gel (17.6 mg/kg body weight) or treated with omeprazole (4 mg/kg body weight) for 28 days. 
Among horses supplemented with aloe vera, 56% experienced improvements in ulcer severity and 17% experienced complete healing. However, this study found omeprazole to be more effective than aloe vera with higher improvement and healing rates.
While not as effective as omeprazole, treatment with aloe vera gel was somewhat effective for gastric lesions. Future studies on dose responses are warranted.
It is important to note that aloe vera should not be supplemented to pregnant mares. There is a risk of adverse effects in pregnant mares.
THE VERDICT Some evidence of efficacy. More research is needed in horses.
10) Bioactive Proteins
Bioactive proteins are protein molecules derived from blood plasma or serum, typically from bovine (cow) or porcine (pig) species.
Bioactive proteins from different animal species have shown benefits for gut health and tissue repair. 
Proposed Mechanism of Action:
- Exerts an anti-inflammatory effect by reducing different inflammatory mediators
- Maintains mucosal integrity by preventing damage from acids in the gastrointestinal tract
- Promotes tissue repair by supplying growth factors
In pigs with ulcers, supplementing the diet with plasma proteins improved tissue repair. These results are attributed to an increase in growth factors. 
The use of bovine bioactive proteins in horses exhibited a significant protective effect against ulcers. 
In one study, horses were supplemented with 210 g of serum bioactive proteins twice per day for 21 days. During the last two weeks, they underwent high-intensity training to induce ulcers.
Only 14% of the horses in the supplemented group developed ulcers compared to 86% in the control group. 
Researchers in this study also examined the effects of feeding 80 g of serum bioactive proteins twice per day. They found that efficacy was lower at this feeding rate suggesting a strong dose-dependant response.
Adding porcine collagen to a horses’ diet was found to increase the effectiveness of omeprazole for the treatment of ulcers. 
Thoroughbred horses were treated with omeprazole and supplemented with porcine collagen at 45 g twice per day for 56 days.
Omeprazole reduced acid secretion in the stomach leading to increased gastric pH.
Horses supplemented with porcine collagen had significantly lower severity of ulcers in the squamous region compared to horses treated with omeprazole alone.
There are other benefits of bioactive proteins in horses, such as improved performance in racehorses.
THE VERDICT: Effective under specific conditions and doses.
11) Corn Oil
Corn oil is a commonly used source of fat in equine diets. This oil is high in the omega-6 fatty acid – linoleic acid.
Research in humans has found that duodenal ulcers are associated with low dietary intake of linoleic acid. 
Linoleic acid may also reduce the secretion of gastric acids which may help to prevent ulcers in horses.
Proposed Mechanism of Action
- Impacts the rate of gastric emptying
- May reduce gastric acid secretion
- Anti-inflammatory effects by increasing prostaglandin concentrations
In ponies, corn oil supplementation at 45 ml per day for five weeks lowered gastric acid production and increased anti-inflammatory prostaglandin levels. 
However, there was no preventative effect on gastric ulcer formation in another study that supplemented corn oil in horses for six weeks. 
A recent study evaluated the effects of corn oil supplementation on healing gastric ulcers.
In this study, researchers separated fifteen horses into three groups receiving either 0 ml, 70 ml, or 90 ml per 100 kg BW of corn oil. 
Corn oil did not alter levels of volatile fatty acids (acetate or butyrate) in the gastric fluid of horses. Elevated volatile fatty acids in the stomach is one of the main causes of gastric ulcers.
However, corn oil did help to improve mucous composition and support ulcer healing in the glandular region. It had no effect on ulcers found in the squamous region.
Despite this mixed evidence, there may be a benefit to providing corn oil to your horse for ulcers in the glandular region of the stomach.
The Verdict: Mixed evidence. Preliminary results suggest a benefit for glandular ulcers.
Zinc plays a role in protein synthesis, immune function, and has antioxidant properties. It is particularly important for wound healing and may be beneficial for preventing gastric ulcers. 
Zinc sulphate has been used in humans to help heal gastric ulcers for many years. 
This mineral has a cytoprotective effect, meaning it helps to stimulate mucus production and enhance blood flow to the intestinal lining. 
Proposed Mechanism of Action:
- Is a component of antioxidant enzymes
- Improves the mucous barrier in the gastrointestinal tract
- Supports circulation to the lining of the gastrointestinal tract
- Promotes tissue repair to help heal ulcers
Zinc has demonstrated efficacy for ulcer healing in a number of animal models as well as human studies. A study in rats demonstrated zinc’s benefits for reducing ulcer development and severity.
Rats on zinc-deficient diets experienced lower rates of ulcer healing compared to those meeting their zinc requirement. 
In a human study, 220 mg of oral zinc sulphate given three times per day was found to improve healing of benign gastric ulcers. Compared to a placebo, the group supplemented with zinc had a higher prevalence of complete ulcer helaing. 
There is less research on the effects of zinc supplementation for ulcers in horses.
One study in horses used a zinc-methionine supplement which showed potential for reducing the recurrence of ulcers. Methionine is an essential amino acid that is commonly deficient in the equine diet.
In 32 horses, ulcers were treated with omeprazole followed by supplementation with zinc-methionine for 49 days. 
Food deprivation was used to induce ulcers. Researchers measured the severity of ulcers in all horses. The severity was reduced with zinc-methionine supplementation.
Unfortunately, this study lacked a control group so it is difficult to make clear conclusions as other factors may have played a role in diminishing ulcer severity.
However, this study provides preliminary evidence that zinc may support the healing of gastric ulcers.
THE VERDICT: Some limited evidence of efficacy for gastric ulcers in horses. More research is required
13) Sea Buckthorn Berries
Extracts of the sea buckthorn plant, Hippohphae rhamnoides, show promising effects in humans for reducing stomach ulcers.
The extract is rich in vitamins and minerals used for wound healing and tissue repair. It also contains amino acids, which are the building blocks of protein. 
Proposed Mechanism of Action:
- Supports healthy tissues with antioxidants (vitamin C and vitamin E)
- Procyanidin, found in sea buckthorn, may promote healing and repair of mucosal cells by increasing growth factors
- Amino acids support protein synthesis and help with tissue repair
In rats, sea buckthorn berry extract appeared to both prevent and treat ulcers that were induced by high levels of acetic acid. 
While the preliminary results in rodents are promising, there is limited evidence in horses.
In one study, eight Thoroughbred horses were either unsupplemented or received 3 oz of sea buckthorn berry extract twice daily. Researchers analyzed the gastric pH level and the number and severity of ulcers in the squamous region of the stomach. 
After 30 days, there were no improvements in ulcers in either group. However, horses when horses were deprived of food to induce ulcers, those supplemented with sea buckthorn berry did not have further increases in the number and severity of ulcers.
Notably, the addition of sea buckthorn berry extract did not alter the gastric acid environment.
In a different study, these benefits were not seen. Horses were supplemented with 35.5 g (4 oz) of sea buckthorn berry extract for five weeks before being deprived of food to induce ulcers.
These researchers found that sea buckthorn berry extract was unable to prevent an increase in ulcer severity. Supplementation did not reduce the total number of ulcers in the squamous region. 
However, they found that horses supplemented with the extract had fewer ulcers and reduced severity of ulcers in the glandular region of the stomach.
In this study, the researchers also noted that supplementation of the extract did not alter gastric pH.
THE VERDICT: Mixed evidence for reducing ulcer severity in horses. More research is required.
14) Wei Le San
Wei Le San, or Xilei San, is an ancient Chinese herbal formulation comprised of nine different herbs.
This herbal blend may be beneficial for reducing inflammation and providing antioxidant protection.
While it has a long history of use in Traditional Chinese Medicine (TCM), there is minimal research on its mechanisms and efficacy.
However, studies in rats show that it can increase epidermal growth factor (EGF), which may help to support healing of gastric ulcers. 
Proposed Mechanism of Action
- Reduces inflammation in the intestinal tract
- Helps maintain appropriate blood flow
- increases EGF, epidermal growth factor receptor (EGFR) and transforming growth factor β1 (TGFβ1) 
Humans with ulcers in the rectal region of the large intestine were supplemented with Wei Le San for four weeks. Supplementation appeared to improve the clinical conditions of ulcers. 
In a study on horses, researchers fed 5 grams of Wei Le San over five weeks. The addition of Wei Le San did not affect gastric ulcer severity compared to a control group. 
THE VERDICT Some evidence of inefficacy in horses which contrasts with results from human and rodent studies.
Licorice root extract from the Glycyrrhiza glabra plant is one of the oldest herbal remedies known to man. It has long been used to ameliorate digestive complaints including heartburn and acid reflux.
Licorice root contains saponins, which are bitter-tasting plant glycosides with bioactive effects in the body. Saponins have surfactant effects that may improve the integrity of the gut mucous barrier.
Licorice extracts have different modes of action for ulcers. The most common form of licorice for supplementation is deglycyrrizinized licorice (DGL).
Proposed Mechanism of Action
- Stimulates mucous production
- Improves mucous composition with incorporation of glycoproteins and protein synthesis
- Inhibits pro-inflammatory mediators such as prostaglandin E2
- Reduces degradation of anti-inflammatory mediators
Licorice supplementation appears to be highly effective for the prevention and treatment of ulcers in rodents.
In rats, extracted DGL exbihits anti-inflammatory effects similar to conventional drug treatments. 
Another study in rats showed anti-ulcer effects of licorice when ulcers were induced by Aspirin in the stomach. 
Traditionally, licorice is used in humans for anti-inflammatory effects to support the alleviation of ulcers.
Humans experiencing gastric irritation reported a significant reduction in symptoms when given DGL. When evaluated on a self-rated scale, licorice was more effective than commonly used antacids for reducing irritation. 
There are no studies evaluating the effects of licorice supplementation in isolation on horses with ulcers. This ingredient is often added to herbal supplement blends for horses.
A pelleted supplement containing DGL, among other ingredients, prevented the worsening of ulcers in horses. 
THE VERDICT High efficacy for ulcers in rodents, and potentially humans. More research required in horses.
Antacids are popular supplements for gastric upset in many species, including horses and humans.
Ulcers are caused by erosion of the intestinal wall by gastric acids. A therapeutic target to prevent ulcers is to reduce the acidity of the stomach.
While conventional wisdom suggests that horses should be fed antacids to reduce ulcer risk, they may cause adverse effects and may not be useful for longterm prevention of gastric ulcers.
The most common antacids for horses are:
- Aluminum hydroxide
- Magnesium hydroxide
- Calcium hydroxide
- Dicalcium phosphate
Antacids work to buffer and raise gastric pH by neutralizing gastric acids. There are concerns with antacid use as they may result in a rise in pH above their natural levels in the stomach.
The purpose of the stomach is to acidify food and activate digestive enzymes. By inhibiting the function of gastric acids, antacid supplements may negatively impact digestive health and nutrient absorption.
Furthermore, there is a risk of acid rebound when antacids are removed from the diet which could result in the recurrence of ulcers.
Proposed Mechanism of Action:
- Maintain and/or neutralize gastric pH
- Neutralizes hydrochloric acid
In an early equine study, an antacid composed of magnesium hydroxide (4.8 g) and aluminum hydroxide (8.1 g) was compared to rantidine and famotidine, two common treatments for gastric ulcers. 
The researchers measured gastric pH levels for 6 hours post-administration.
Before treatment, gastric pH in the horses was approximately 1.8. The pH increased slightly and only for a short period with antacid solutions. In comparison, ranitidine and famotidine treatments increased pH to 6 in the treated horses for 1.5 to 2 hours.
Alternatively, gastric pH levels were raised to 5 for 2 hours post-administration when five healthy horses were provided a treatment of 30 g aluminum hydroxide/15 g magnesium hydroxide. 
Doses lower than this did not significantly raise the pH levels of gastric juices.
A recent study evaluated an supplement combination with an antacid and yeast for the prevention of increased of ulcer severity in Thoroughbred racehorses. 
Twenty-four horses with mild gastric ulcerations were fed either 20 grams of magnesium hydroxide and 2 grams of Saccharomyces cerevisiae or a pelleted placebo.
Horses given the placebo experienced a significant increase in ulceration severity, whereas horses given the antacid-yeast supplement did not experience worsening ulcerations.
No improvements in ulcers were observed. The antacid only prevented the worsening of ulcers in these horses.
Raising stomach pH levels for long periods of time is not recommended. The pH levels in this study were above the preferred concentrations for horses.
Furthermore, the effects of antacids are short-lived. Horses would require supplementation every few hours to maintain efficacy.
This is unrealistic and ultimately suggests no long-term efficacy for providing antacid supplements to your horse.
At best, an antacid may provide immediate relief. However, other supplements and treatments will provide better long-term results. 
The Verdict:Poor efficacy for long-term prevention and treatment of ulcers in horses.
How to Reduce Ulcer Risk for your Horse
Current drug therapies like omeprazole work to alleviate ulcers in horses. Unfortunately, these treatments tend to result in relapse after the drug is removed.
Natural dietary supplements are preferred because they support the horse’s biology to promote the healing of ulcers and to maintain gut barrier function.
There are many factors that contribute to the onset of equine ulcers. If your horse has developed ulcers, it is important to address the root cause of this condition.
Factors that can affect ulcer risk include: 
- Intermittent feeding or limited access to forage throughout the day
- Dietary components, such as high-grain or high-concentrate diets
- High-intensity exercise regimens
- Environmental stressors such as stall confinement and transport
- Social stress such as herd changes
This list of supplements for equine ulcers is not exhaustive. However, this review should provide you with some information on choosing the best supplement for your horse.
Mad Barn developed Visceral+ as an all-in-one ulcer formula using the best science available to avoid the need to feed individual supplements.
Consult with an equine nutritionist or other equine healthcare professionals when adding supplements to your horse’s diet.
You can submit your horse’s diet for a complimentary analysis online and one of our qualified equine nutritionists can give you advice on how to feed your horse to reduce ulcer risk.
If you are concerned that your horse has gastric ulcers look for these common signs and symptoms, and follow up with your equine veterinarian.
Is Your Horse's Diet Missing Anything?
Identify gaps in your horse's nutrition program to optimize their well-being.
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