Nutrition and feeding play an integral role in the prevention of equine ulcers. Ulcer-prone horses can benefit greatly from a feeding program that supports gut health and supports the horse’s natural defences against ulcers.

Equine ulcers are painful sores or lesions that develop along the digestive tract lining. They can cause poor performance, aggression, and girthiness in your horse.

Forage type, meal size, meal composition, and feeding frequency can all impact ulcer risk. These factors are so critical that poor feed management can significantly increase your horse’s likelihood of developing ulcers.

A well-structured feeding program that accommodates species-appropriate foraging behaviours will limit the time your horse spends with an empty stomach. This will help to buffer against gastric acids that can cause ulcers to form.

Reducing the amount of grain and concentrates in your horse’s diet, ensuring access to water, and feeding certain gut-healthy foods can also defend against ulcers.

Looking for assistance with designing a diet for your horse to reduce their risk of ulcers or promote ulcer recovery? Submit your horse’s diet online and our nutritionists can help!

Ulcer Risk in Horses

Equine ulcers can affect up to 93% of horses, making them one of the most commonly diagnosed digestive health conditions in horses.[1]

Ulcers are characterized as open sores or lesions that occur along the lining of the gastrointestinal tract. They form when stomach acids erode the protective layers of the gastrointestinal lining.

Ulcers can develop anywhere along the gastrointestinal tract, though they occur most commonly in the stomach. When ulcers occur in the hindgut, this is referred to as Right Dorsal Colitis.

All horses can be affected by ulcers, but some are more prone than others. The following rates of ulcer prevalence have been observed:

  • Endurance horses (competition season): 90-100%
  • Standardbred or Thoroughbred horses: 58-88%
  • Performance horses: 40-60%
  • Endurance horses (off-season): 48 %
  • Pleasure horses: 53%

The higher prevalence in some competition horses attributed to greater exposure to common ulcer risk factors.

The causation of ulcers is often multi-factorial, meaning several interacting risk factors can play a role in any given case of ulcers.

Potential contributing risk factors include:

  • High-intensity exercise
  • Frequent anti-inflammatory drug use (ie. NSAIDs)
  • Stressful social environments
  • Physical stressors (ie. Stall confinement, travel, change in routine)
  • Intermittent access to feed and water
  • Poor feed quality and diet composition
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Why Do Horses Get Gastric Ulcers?

Wild horses are not prone to gastric ulceration, so why do domesticated horses have such high rates of this condition?

Gastric ulcers are unfortunately an artifact of modern equine management practices. This is why as horse owners we have a responsibility to manage our horses in a way that minimizes ulcer risk.

The horse’s stomach continuously produces acids, such as hydrochloric acid, whether or not there is food to digest. This creates a highly acidic environment in the stomach that is a major risk factor for ulcer development.

A typical 500 kg (1100 lbs) horse can produce up to 60 litres (16 gallons) of gastric acids per day!

Gastric Acids and Ulcers

There are two compartments that make up the equine stomach: the upper squamous region (including the esophagus) and the glandular region.

The glandular region of the stomach produces mucous and bicarbonate to create a natural barrier between the acid and stomach lining, and neutralize stomach acids.

Up to 80 % of diagnosed ulcers are located in the upper squamous region of the stomach. This region does not have a mucous barrier to protect the stomach wall from gastric juices.

When stomach tissue comes into direct contact with stomach acids, the tissue is eroded and sores can form.

Natural Ulcer Protection

To protect against stomach acids, the upper squamous region normally relies on food, water, and saliva as a buffer. Eating and drinking help to neutralize stomach acids. Food in the stomach can also create a barrier between the acid-producing glandular region and the upper squamous region.

Horses that graze continuously throughout the day are protected against ulcers. These horses have a stomach pH (level of acidity) between 2 – 4.

Horses that go only three or four hours without food experience a dramatic drop in stomach pH. This increased acidity can induce ulcers.

In fact, intermittent feeding is used as a method in research studies to induce gastric ulceration in horses.

Given the importance of continuous grazing, how can you feed your horse to reduce ulcer risk and support digestive health?

Here we provide an in-depth feeding guide in 12 easy steps for horses that are prone to ulcers.

Feeding Program For Ulcer-Prone Horses

Step 1) Determine Your Horse’s Nutritional Needs

To create an optimal feeding program, you should evaluate your horse’s current diet, health status and nutritional needs.

All horses need to engage in species-appropriate foraging behaviours, which means they need to be eating for at least 12 hours a day.

In addition to this, they need to meet their nutritional requirements for energy, protein, fat, minerals and vitamins.

Factors that alter your horse’s nutritional requirements include: [2]

  • Age
  • Health status
  • Lifestyle
  • Breed of horse
  • Activity level
  • Body weight
  • Body condition
  • Reproductive status

From there, tailor your feeding program to your individual horse, to their housing situation and to which feeds are available in your geographic region.

Analyzing the macro- and micro-nutrients that your horse’s diet currently provides will help you fill in any potential gaps.

This is best achieved with a hay analysis. Closely examining the feed tags for any complete feeds or ration balancers you provide is also important to assess whether they are the right option for your horse.

At Mad Barn, we design thousands of feeding programs for horses every year and all of our diet plans start with these principles in mind.

If you need help with analyzing your horse’s current diet, submit your feeding program online and our nutritionists can provide you with a complementary review.

Build every feeding program from the ground up involves meeting your horse’s need to eat for at least 12 hours a day and fulfilling requirements for energy, protein, fat, minerals and vitamins.


Step 2) Forage and Hay Selection

Ulcer-prone horses will benefit from a forage-first diet. Hay is naturally lower in non-structural carbohydrates (NSC) than grains or concentrates.

This is beneficial for gut health as high NSC feeds can result in excessive acidity due to overproduction of volatile fatty acids (VFAs).

Hay also contains fibre which has a prebiotic effect to support gut health and hindgut fermentation.

Consumption of fibrous foods is particularly beneficial for horses prior to exercise. Fibre appears to reduce the splashing of gastric acids into the squamous region of the stomach during exercise.

Hay, or forage, should account for 1.5 to 2% of your horse’s body weight per day. That means that a 500 kg horse should consume 7.5 to 10 kg of forage each day.

Hay Selection

The type of hay provided can also affect your horse’s digestive health. For horses prone to ulcers, select hay that is high in structural carbohydrates and low in non-structural carbohydrates.

Opt for hays with higher protein and calcium content. Legume hays are a great option, the most popular being alfalfa hay.

Alfalfa hay contains 15 to 25% crude protein. Compared to grass hay which consists of 10% crude protein, alfalfa provides almost twice as much protein.

Alfalfa is also a good source of the mineral calcium, which buffers stomach acid. [3]

Some horses may be sensitive to alfalfa hay, including horses with equine metabolic syndrome or insulin resistance. Alfalfa also tends to be more expensive and may not be available in all areas.

In these cases, you can incorporate other options such as bromegrass, timothy, bermudagrass, and oat hays.

Hay Quality

When sourcing hay, consider the time of harvest, soil condition, and geographical location where it was grown. These factors can impact the nutritional value of hay.[4]

Store forage in a dry, cool, and dark environment to avoid exposure to moisture. Moisture can result in mould growth, which is a source of toxins that can disrupt your horse’s gut microbiome.[5]

Obtain a hay sample analysis to gain better insight into your horse’s nutritional profile.

Discuss hay selection with a qualified equine nutritionist or veterinarian if your horse has other health concerns.

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Hays that are high in protein and calcium and low in NSC are beneficial for ulcer-prone horses. Store hay away from moisture to reduce mould growth.

Step 3) Limit Grain Intake

High grain diets are a risk factor for ulcers for multiple reasons.

First, grains do not require as much chewing, which reduces saliva production. Less saliva means less buffering capacity in the stomach.[3]

Second, grains move more rapidly through the stomach, which means the stomach is empty for longer periods on a high-grain diet.[6]

Third, the higher NSC content of grains results in greater volatile fatty acid (VFA) production.

Horses use VFAs for energy, but excess VFA production can reduce foregut and hindgut pH levels, resulting in acidosis.

Keep starch intake below 1 gram per kg of bodyweight at each meal (500 grams starch for a 500 kg horse), or no more than 2 grams of starch per kg bodyweight per day (1000 grams starch for a 500 kg horse).[3]

Grains are high in NSC, which hinder the buffering capacity of the stomach. Limit starch intake to 2 grams per kg of BW per day. Consider substituting grains with other energy sources, such as dietary fats or proteins.

Step 4) Feed Forage, Hay, or Chaff with High Grain Meals

As described above, meals that are predominantly composed of grains work against the natural buffering capacity of the stomach.

If you are feeding grains, it is recommended to feed alongside forage, hay, or chaffs (chopped hay).

These feeds require more chewing which increases saliva production. Saliva acts as a buffer for the squamous region of the stomach.

These fibre-rich foods also have slower transit through the stomach, reducing the amount of time the stomach is empty between meals.

When feeding your horse grains or concentrates, consider also providing forage, hay, or chaff to slow gastric emptying and protect your horse’s stomach.

Step 5) Prolong Foraging Time

Increase the amount of time your horse spends foraging and eating to limit long periods in which your horse’s stomach is empty.

Slow feed hay nets are a great option to extend the amount of time your horse spends feeding and keep the stomach full for longer. Hay nets are great for easy-keepers or horses that need to lose weight as they can prevent oversupplying calories.

To encourage foraging behaviour, also consider spreading multiple hay nets around the stable or pasture.

Intermittent access to forage is directly linked to ulcer onset. Horses fed only two meals per day had a greater prevalence of ulcers than horses provided 20 small meals per day. [7]

To encourage grazing, increase turnout times and reduce stall confinement. Horses that are stall confined for long periods during the day are also at greater risk for ulcers.[8]

Give your horse lots of turnout and consider using hay nets. This will increase the amount of time your horse spends eating and reduce time spent with an empty stomach.

Step 6) Maintain a Regular Feeding Schedule

Keep regularly scheduled meal times, especially for grains and concentrates to minimize digestive upset.

Like humans, horses have an internal clock that signals when to eat. Hormonal signals stimulate hunger and foraging behaviours.

Sporadic feeding schedules can cause stress and result in cribbing, wood chewing, soil licking and other unwanted behaviours.

Horse owners using a complete feed may find it more convenient to give their horse their daily ration all at once. However, research shows that this can increase ulcer risk.

Split any concentrates over multiple small meals -two at a minimum.

Changes in routine may stress your horse, which can increase ulcer risk. Keep your horse on a regular schedule for mealtimes.

Step 7) Increase Protein Intake

Horses recovering from ulcers benefit from increased protein intake. Proteins are composed of amino acids and are fundamental for building, maintaining and repairing tissues.

According to the National Research Council (2007), horses at maintenance require 8-10% protein in their diet. For a 500 kg horse, this is 630 grams of crude protein per day. [2]

The protein requirement is higher in horses with ulcers to support tissue repair and wound healing in the gastrointestinal tract.

Feeding amino acids such as glycine and glutamine can help to promote ulcer healing. [10][11][12]

Protein can also play a role in ulcer prevention. Protein appears to have an acid buffering effect in the stomach.

Researchers found that horses fed protein-rich alfalfa hay experienced a buffering effect that lasted up to 6 hours. [9]

Protein Sources for Horses

To increase your horse’s dietary supply of protein, choose hay or forage that is high in crude protein like alfalfa.

You can also feed the following protein-rich foods:

  • Spirulina: 52% crude protein
  • Soybean meal: 44-48% crude protein
  • Canola meal: 36-41% crude protein
  • Ground flax: 26% crude protein
Horses affected by ulcers have higher protein requirements to support tissue repair. Increase your horse’s protein intake by feeding alfalfa hay, spirulina, soybean meal or other high-protein food horses.

Step 8) Choose Fats to Add Caloric Energy

Using dietary fats as an energy source can be a great option for ulcer-prone horses, especially if fats can eliminate the need for grains.

Adding fats to the diet may also slow food transit out of the stomach, and reduce the amount of time that the stomach is empty.

Total fat content in the equine diet should remain below 8%, or 2 cups per day for a 500 kg horse. Horses also obtain fats from grains and concentrate; these amounts should be factored in when determining how much to feed.

Omega-3 vs. Omega-6 Fats

Vegetable oils such as canola or corn oil can be used to add caloric energy at a very low cost.

However, these oils are low in omega-3’s and high in linoleic acid – an omega-6 fatty acid. Horses already tend to have an over-abundance of omega-6 to omega-3 fats and too much vegetable oil could throw off this balance.

Consider incorporating fats that contain omega-3 fatty acids, like flax oil, camelina oil, or Mad Barn’s w-3 Oil. Omega-3’s like DHA are well-known for their anti-inflammatory effects which supports healthy tissue repair. [13]

w-3 Oil

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  • Promotes joint comfort
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Replacing grains with dietary fats as an energy source can reduce ulcer risk. Fats that are rich in omega-3 fatty acids have added health benefits.

Step 9) Ensure Adequate Water Intake

Horse owners often overlook hydration when it comes to ulcer prevention. Horses at risk of ulcers will benefit from having fresh, clean water available at all times.

Water dilutes gastric fluids and reduces stomach acidity. Water can also improve the transit of food through the gastrointestinal tract.

Research shows that horses without constant access to water are 2.5 times more likely to develop ulcers. [14]

To encourage hydration, feed 1-2 tablespoons of plain salt per day and offer free-choice loose salt. A salt lick can encourage water consumption, but may not provide enough salt and may cause sores on the tongue.

Give your horse access to fresh, clean water at all times and provide free-choice loose salt to encourage hydration. Water dilutes gastric acids and supports food transit through the gastrointestinal tract.

Step 10) Feed Your Horse Before Exercise

Regular exercise can help to increase gut motility, promote water intake, and support your horse’s overall health.

However, excess exercise is strongly associated with increased ulcer risk.[1] In particular, exercising your horse on an empty stomach is extremely likely to cause ulcers.

Exercise has been shown to compress the stomach and increase hydrochloric acid production. [15][16][17] This compression and movement can cause gastric acids to splash out of the protected glandular region of the stomach and into the unprotected squamous region.

Where possible, consider reducing exercise intensity, duration, and frequency for horses at high risk of ulcers. In equine athletes where this is not possible, other mitigation strategies become even more important.

Providing hay or forage before exercise can create a fibrous barrier in the stomach. This barrier can protect the squamous region from increased acid production and compression during exercise.

High-intensity exercise greatly increases your horse’s risk for ulcers. Never exercise your horse on an empty stomach. Provide hay or chaff to protect the stomach during exercise.

Step 11) Feed Natural Ulcer Supplements

Several natural dietary supplements have good evidence for helping to maintain stomach and hindgut health in horses.

You can find out more in our research review of the Top 16 Natural Ulcer Supplements for Horses.

Some ingredients that may be beneficial for ulcer-prone horses include:

  • Probiotics and prebiotics
  • Yeast
  • Digestive enzymes
  • Bioactive proteins
  • Marshmallow extract
  • Lecithin – a phospholipid
  • Slippery Elm Bark

Following changes to your horse’s nutrition and management plans, consider adding Mad Barn’s Visceral+ to support gastric and hindgut health.

It is a pelleted supplement that also supports immune function.


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Step 12) Introduce Feed Changes Gradually

Abrupt changes in your horse’s feeding program and routine may cause stress, which can exacerbate ulcer risk.

Hay changes are a significant factor for digestive upset and ulcers. Research shows that feeding hays with different nutrient compositions can alter microbial populations throughout the digestive tract. [6]

When making changes to your horse’s feeding program – such as the suggestions made in this guide – do so over a two-to-three-week period.

Gradually replace a small percentage of your horse’s current feed with the new feed until your horse is fully switched over.

If altering your horse’s feeding schedule, introduce changes incrementally, such as moving feeding times by 30 minutes to an hour at most.

Your horse needs time to adapt to changes in diet and feeding routine. Gradually introduce new feed or new routines over a 2 to 3 week period.

Additional Preventative Measures

Horses prone to digestive issues may also benefit from non-nutritional strategies to naturally prevent ulcers.

Some additional measures you can take to keep your horse safe from ulcers include:

  • Prevent acid rebound after treatment of ulcers
  • Minimize the use of NSAIDs
  • Reduce travel when possible
  • Avoid stall confinement
  • Maintain positive socialization
  • Minimize exposure to new environments
  • Do not use antacids for ulcers

Discuss with a qualified equine nutritionist or your veterinarian before making significant changes to your horse’s diet or routine.

Signs & Symptoms of Ulcers

Not all horses that are affected by ulcers will display outward signs. But many will display certain characteristic behaviours, such as girthiness, reduced appetite and reluctance to work.

If you do begin to notice the following telltale signs of ulcers, contact your veterinarian for an examination.

  • Poor appetite or picky eating
  • Chronic diarrhea
  • Weight loss and/or poor body condition
  • Stretching to urinate
  • Increased aggression
  • Reduced performance
  • Poor coat condition
  • Recurrent colic
  • Behavioural changes (ie. nervous disposition)
  • Sensitivity in the girth area
  • Cribbing, teeth grinding, and other stereotypic behaviours
  • Excessive salivation
  • Excessive recumbency

Treatment for Equine Ulcers

The only FDA-approved drug for treating equine ulcers is omeprazole. It is sold under the tradenames GastroGard and UlcerGard.

Omeprazole is a proton-pump inhibitor that raises stomach pH and allows ulcers to heal.

Other available treatment options that are not FDA-approved include Ranitidine or Cimetidine, which have antihistamine properties. Additionally, coating or binding agents, synthetic hormones, prokinetic agents, antibiotics, or a combination of several therapies may be used. [18]

Treating equine ulcers can be a long and costly commitment, and horses often experience high rates of recurrence. This makes it even more important to mitigate ulcer risk through feeding practices and management changes.

If you believe your horse may be affected by ulcers, contact your veterinarian for a full diagnosis. Your veterinarian can help you better understand available treatment options, including omeprazole, and how to minimize the risk of ulcer rebound.

Looking for help with feeding your ulcer-prone horse? Our nutritionist can help you designed a balance feeding program for your horse for free.

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  1. Tamzali, Y. et al. Prevalence of gastric ulcer syndrome in high-level endurance horses. Equine Vet J. 2011.View Summary
  2. National Research Council Nutrient Requirements of Horses. 2007.
  3. Nadeau, J.A. et al. Evaluation of diet as a cause of gastric ulcers in horses. Am J Vet Res. 2000. View Summary
  4. Rotz, C.A.How to maintain forage quality during harvest and storage. Advan Dairy Tech. 2003.
  5. Goncalves, S. et al.Risk factors associated with colic in horses. Vet Res. 2002. View Summary
  6. Geor, R.J. and Harris, P.A.How to minimize gastrointestinal disease associated with carbohydrate nutrition in horses. Proceedings Annual Convention of the AAEP. 2007.
  7. Bass, L. et al. Effects of feeding frequency using a commercial automated feeding device on gastric ulceration in exercised Quarter horses. J Equine Vet Sci. 2018. View Summary
  8. Murray, M.J. Equine model of inducing ulceration in alimentary squamous epithelial mucosa. Digest Dis Sci. 1994. View Summary
  9. Nadeau, J.A. et al. The effect of diet on severity of gastric ulcers in horses. Gastroenterol. 1998.
  10. Rotting, A.K. et al. Effects of phenylbutazone, indomethacin, prostaglandin E2, butyrate, and glutamine on restitution of oxidant-injured right dorsal colon of horses in vitro.. Am J Vet Res, 2004. View Summary
  11. Andrews, F.M. et al. Effect of a pelleted supplement fed during and after omeprazole treatment on nonglandular gastric ulcer scores and gastric juice pH in horses.. Equine Vet Ed. 2015.
  12. Wang, W. et al. Glycine metabolism in animals and humans: implications for nutrition and health. J Amino Acids. 2013.
  13. Hess, T. and Ross-Jones, T. Omega-3 fatty acid supplementation in horses. R Bras Zootech. 2014.
  14. Luthersson, N. et al. Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark. Equine Vet J. 2009.View Summary
  15. Lorenzo, M. et al. Barostatic evaluation of the effect of exercise on the equine proximal stomach. Gastroenterol. 2001.
  16. Furr, M. and Kronfeld, T.D. The Effect of exercise training on serum gastrin responses in the horse. Cornell Vet. 1994.View Summary
  17. Pagan, J.D. et al. Exercise affects digestibility and rate of passage of all-forage and mixed diets in Thoroughbred horses. J Nutr. 1998. View Summary
  18. Videla, R. and Andrews, F.M. New perspectives in equine gastric ulcer syndrome. Vet Clin North Am Equine Prac. 2009. View Summary