You would consider equine gastric ulcers to be rather uncommon, but nothing could be further from the truth. Scientific research shows that 1 out of 2 horses will be diagnosed with a gastric ulcer during their lifetime.

In performance horses, this percentage is considerably higher. For instance, 70% of Endurance horses get a gastric ulcer. In thoroughbred racehorses, with an average of 90%, only 1 out of 10 racehorses does not get an ulcer!!!

A shocking result. But don't be fooled, 36 to 53% of pleasure horses also get ulcers. Continue reading and discover risk factors, clinical signs and possible solutions for the equine health of both foals and adult horses.

• What are gastric ulcers in horses?
• 4 types of equine gastric ulcers
• ESGUS - gastric ulcers in the upper part of the stomach
• EGGUS - stomach ulcers in the lower part of the stomach
• Gastric ulcers in the transition line (margo plicatus)
• How do gastric ulcers occur?
• Causes of gastric ulcers
• Stress - the main cause of gastric ulcers
• Feed and feed management
• Clinic stay
• Training
• Transport, Competition, Events
• How do you know your horse has a stomach ulcer?
• What are the symptoms of a stomach ulcer?
• First aid: what to do if you suspect a gastric ulcer
• How is a gastric ulcers diagnosed?
• Treatment of horses with gastric ulcers
• How quickly does a horse´s gastric ulcers heal?
• Is a gastric ulcer life-threatening for a horse?
• Can you ride a horse with a gastric ulcer?
• What happens after omeprazole treatment?

What are gastric ulcers in horses?

A gastric ulcer in the horse (Equine Gastric Ulcer Syndrome, EGUS) basically results from a lesion of the gastric mucosa.

A lesion is damaged tissue or an injury to the stomach wall lining. This is often caused by stress-related interruption of the renewal of the gastric mucous membrane. Leading to inadequate protection against acidic fluid. In addition, the proportion of acid in the horse's stomach is often too high, because there is not enough feed available to buffer the stomach acid, or eating breaks are too long.

A distinction is made between three different forms of lesions:

1. inflammations
2. infestations
3. ulcers

4 types of equine gastric ulcers

EGUS, Equine Gastric Ulcer Syndrome, is the general term for gastric ulceration. Within 24 to 48 hours, a mucous irritation can develop into a crater-shaped gastric ulcer.

Depending on the physical location, a distinction is made between ulcers in the squamous part (ESGUS: Equine Squamous Gastric Ulcer Syndrome or Equine Squamous Gastric Disease) and the glandular part (EGGUS: Equine Glandular Gastric Ulcer Syndrome or Equine Glandular Gastric Disease) of the horse's stomach.

A lesion may also be localized exactly at the boundary of these two gastric zones. Finally, a gastric ulcer can occur at the gastric outlet (pylorus). Duodenal ulceration in adult horses and foals is considered part of EGUS.

ESGUS - gastric ulcers in the upper part of the stomach

The upper part of the stomach, unlike the glandular part, does not contain mucus-producing glands that can form a protective layer against gastric acid. Therefore, the rather unprotected squamous mucosa of the horses' upper stomach is more likely to be affected by ulcers.

If the gastric mucous membrane production is interrupted, the danger for gastric ulcers in this upper part is largest, so-called squamous ulcers.

EGGUS - stomach ulcers in the lower part of the stomach

Although ulcers are less common in the lower part of the stomach, the glandular region, they should not be overlooked. Mucus producing cells inhibit the influence of gastric acid. Since stomach acid is permanently present in the lower part, it cannot be identified as the sole cause of glandular ulcers. Horses with ulcers in the glandular region are referred to as having Equine Glandular Gastric Disease (EGGD)

Gastric ulcers in the transition line (margo plicatus)

The margo plicatus separates the above parts by means of a transition line. Damage also occurs at this border area. Which can lead to inflammation, lesions and ulcers of the stomach wall.

Stomach ulcers at the gastric outlet

The connection from the stomach to the duodenum, the pylorus, is a fourth location where gastric ulcers occur. Research using gastroscopy shows that there is a proportional relationship between the performance level of horses, the risk of lesions in this area and duodenal ulcers.

How do gastric ulcers occur?

For effective treatment of gastric ulcers, some prior knowledge of the anatomy of the horse's stomach and stomach wall is desirable. Horses have a comparatively small stomach, which acts as a conduit to the intestines.

The storage capacity of 15 litres is limited. The entrance to the stomach (cardia) connects the oesophagus to the stomach.

The equine stomach belongs to the compound stomachs, consisting of two parts - the squamous mucosa of the upper part, and the glandular mucosa of the lower part. The margo plicatus separates the two parts in the form of a boundary line. The gastric outlet is called the pylorus and connects the stomach to the duodenum.

Digestive enzymes need an acidic environment. In addition, bacteria and other micro-organisms are killed in this acidic environment of the horse stomach.

Humans cope well with irregular food intake because stomach acid is produced the moment we eat. However, the horse produces these acids 24/7, regardless of the presence of food.

Due to this non-stop production, a surplus of acid occurs if no food ends up in the stomach. As a result, the stomach wall can become irritated. Which is very painful for horses with gastric ulcers.

Stomach acid is extremely powerful and would directly affect the gastric mucosa if it did not have a protective mucus layer.

Things go wrong when we do not mimic the horse's natural nutritional intake well enough. Evolutionary, as herd and step animals, they are continuous eaters. Their stomachs are set to continuously consume a small amount of nutrient-poor roughage.

So that the digestive process does not grind to a halt, stomach acid is produced non-stop. Saliva and feed act as buffers. The feed absorbs, whilst saliva help neutralize stomach acid.

The natural acid-buffer in saliva, bicarbonate, is produced only during the chewing and grinding process. Continuous foraging, as in the wild, maintains the natural balance between bicarbonate and stomach acid.

As a result, horses produce between 40 to 60 litres of saliva a day, mainly by chewing and grinding feeds high in crude fibre. Plenty of horses get two or three meals per day, where large portions are served. Most often horses encounter too little crude fibre, yet too much concentrates. Apart from these few feeding sessions, the stomach has no work to do. This manifests itself in reduced appetite or, on the contrary, obsessive eating behaviour and can cause various problems, such as gastric ulcers.

Causes of gastric ulcers

Housing and nutrition of domesticated horses have changed enormously over the past decades. Too small portions of roughage result in a lopsided stomach's natural balance. Healthy stomach function is compromised.

Overuse of anti-inflammatory drugs is also found to be causing severe ulceration. Lack of free exercise, eating breaks that are too long, irregular feeding times, intensive training, unfriendly "box neighbours", a non-harmonious group composition at the paddock or pasture, and so on, can mean be triggers. But why do horses get gastric ulcers?

Stress - the main cause of gastric ulcers

According to many vets, stress-related overproduction of stomach acid is the main cause of gastric ulcers. This is actually incorrect, as horses produce them 24/7, so there is no over-production. It is rather the bare emptiness of the stomach that causes problems. Lack of (low fibre) food. Stomach acid itself is not bad; the horse's stomach is quite resistant to and even dependent on them.

Stomach acid plays an important role in digestion: it is absorbed by food - regardless if it's hay / oats or concentrates - and in combination with saliva, produced during chewing, the digestion in the stomach starts. Furthermore, it kills bacteria.

But as always, the dose determines the poison! Many horses have an abundance of stomach acid because not enough roughage is fed, as a result the unprotected upper stomach wall can be damaged. Worst case scenario is when there is no food at all present in the stomach, the acid dances around like a small lake, damaging the mucous membrane.

Especially at trot and gallop, horses show discomfort and pain. Therefore, you should not ride your horse on a (roughage) empty stomach. Stress has another influence: cortisol levels increase during stress. There is decreased blood flow towards the stomach, making the stomach wall less nourished, more sensitive to acid and less capable to regenerate.

Irritation of the stomach lining causes abdominal pain, resulting in the horse experiencing even more stress. This creates the risk of a vicious circle. Physical and environmental stressors should therefore be avoided as much as possible.

Illness, lameness, pain, a strange environment, being in the stable for long periods, stall confinement, transport, surgeries, but most certainly also unpredictability and lack of routine create physical and environmental risk factors for most horses and thus increase the risk of gastric ulcers.

Feed and feed management

Because, unfortunately, many horse owners discover too late that the diet or housing is not optimal for their horse's equine health, gastric ulcers usually go unnoticed at first. Even after successful treatment, the ulcers return. Food and housing adapted to the type of horse are essential in preventing gastric ulcers.

Above all, this means that a horse must have sufficient high-quality roughage available. Supplemented, if necessary, by suitable mineral feed. To ensure high saliva production to buffer stomach acids, and decrease the risk of squamous ulcers, long feeding breaks and irregular feeding times should be avoided.

Mimicking natural feed intake as much as possible will also benefit horses in current housing systems. In addition, there are special feeds and supplements that can accurately support the horse with a sensitive stomach or stomach ulcers.

In general, it is advisable to feed a horse roughage before feeding concentrates. Divide sufficient roughage into as many portions per day as possible. Or even provide unlimited roughage. Because the shorter the breaks in between eating are, the lower the risk of excess acid that can damage the stomach wall. The norm for sufficient roughage is at least 1.5% of the desired (!) body weight in dry matter, per day.

What about Alfalfa hay?

Alfalfa (lucerne) hay can, on the short term, substitute hay or other roughage, as it will certainly stimulate saliva production compared to high grain diets. Some research suggests that the sharp structure of chopped alfalfa does not have a particularly positive effect on the gastric mucosa, but rather causes mechanical irritation of the gastric mucosa and thus gastric mucosal lesions.

Therefore, alfalfa, which in itself is a high-quality food plant for the horse, should preferably be fed as a pellet or extrudate. Unfortunately, high levels of lucerne hay or chaff may not be desirable for some horses due to its high calorie, protein, and calcium levels. Always have an equine nutritionist review your horses’ diets to ensure the best combination of feed and forage for their age, weight, breed, and workload.

Clinic stay

An unfamiliar environment, stall confinement, strange scents and a horse that generally does not feel top notch. Clinic stays generally involve a lot of stress.

In addition, a horse needs to be sober, at least 12 hours without food and 6 hours without water, before an examination or surgery can be performed. In the case of gastric ulcers, where the stomach is examined by gastroscopy, this is counterproductive in the thoughts of many horsepeople. But sometimes this is the only way, to figure out about the grades of gastric ulcers.

Luckily, visiting a clinic, undergoing an extensive check and treatment with medicines, are in most cases not the only solutions possible.

Training

Horses that have to perform during intense exercise do not eat for several hours during that training. As a result, not enough saliva enters the stomach, hence the acid is not buffered.

This can cause damage to the stomach lining and ultimately stomach ulcers. Pay attention to regular breaks between training sessions, as during exercise digestion is virtually shut down.

There is also an increased abdominal pressure during intense exercise. This pushes the acid up into the stomach, making it easier to damage the squamous region.

Transport, competitions, events

It is crucial to remember that horses, as typical creatures of habit, need a regular daily routine. Fixed feeding times, the same actions at the same time, preferably in the same order and at the same way.

Disruptions in routine bring uncertainty and thus stress. Always make sure there is enough water available during transport, competitions and events. Fun fact: Isabell Werth (German gold medallist in dressage at each of the six Olympic Games she encountered) changes her routine quite some time before a competition to match the time of day her horses will have to perform on 'game-day'.

How do you know your horse has a stomach ulcer?

Based on certain symptoms, you suspect your horse has a gastric ulcer. By an endoscopic examination your vet can perform a gastroscopy to determine whether your suspicion of an equine glandular gastric disease is correct.

What are the symptoms of equine gastric ulcers?

The main and most common clinical signs of equine ulcers are:
1. Poor appetite: Horses with stomach problems generally have poor appetite. They spill feed and ignore it. In short, your horse eats with less enthusiasm. This is partly because it is very painful when the inflamed parts of the stomach come into contact with acids.

2. Weight loss: Due to reduced feed intake, the organism is no longer supplied with sufficient energy and nutrients, body weight decreases. Weight loss and poor body condition will be the first things you notice.

3. Colic. Recurrent colic, intermittent colic, or even vague colic complaints: The horse stands with its belly raised after eating (concentrate feed), looks at its belly, lies down, rolls and stands up again. These positions seem to provide some relief from severe gastric ulceration.

4. Dull coat: Not every horse with gastric ulcers has a bad coat! Many horses suffering of severe ulcers have a shiny coat and appear externally healthy. Sometimes, due to the disturbed metabolism, sufficient nutrients are no longer available and the coat loses its shine - hence the dull coat.

5. Poor performance: Stomach pain and reduced nutrient absorption can lead to a drop in performance levels. The horse does not have enough energy to do the job.

6. Yawning more often: If a horse yawns constantly, it is a relatively clear indication of disorders of the gastrointestinal tract. On the other hand, horses yawn to lower their stress levels. If horses with gastrointestinal complaints or severe ulceration have anything in abundance, it is stress - either as a trigger for the gastric ulcer and/or as a result of pain.

Other symptoms may include flehmen, cribbing, isolation from the herd, a girthy horse, increased saliva production and tail swishing. See also: 21 main symptoms of gastric ulcers in horses. Download our E-Book for free!

First aid: what to do if you suspect a gastric ulcer

If you suspect a gastric ulcer, reduce stress, offer plenty of good forage, ease your horse's workload and call your veterinarian. There is no true home "treatment," but a few steps make your horse more comfortable and stop the situation from getting worse while you get a diagnosis.

Reduce stress. Stress has many sources and contributes heavily to gastric ulcers, so start by looking at where your horse's stress comes from — turnout, herd, routine, feeding gaps — and take pressure off wherever you can. For a deeper look, see our free e-book on stress in horses.

Adjust the feeding. Offer plenty of high-quality forage and feed concentrates only in moderation, if at all, following the feeding guidance above.

Buffer the stomach acid. A natural buffer supplement such as Equine 74 Gastric can help soak up the excess stomach acid that builds up from feeding gaps and stress, as one part of a broader management plan alongside your vet.

Ease the workload. A gastric ulcer can be very painful, so take that into account and avoid demanding work. Too little recovery time between sessions can itself contribute to ulcers.

Involve your veterinarian. When in doubt, talk to your vet — especially in acute cases, they can give you the best individual advice, and a gastroscopy is the only way to confirm an ulcer for certain.

How is a gastric ulcer diagnosed?

Apart from recognizing clinical signs, the only way to make a definitive diagnosis is through a gastroscopy. This involves the vet inserting an endoscope through the nose into the stomach. This allows the oesophagus, the inside of the stomach and the first part of the (small intestine) to be inspected.

The number, severity and type of stomach ulcers can be diagnosed this way. Subsequently, it is often difficult to find out what the exact cause was.

Treatment of horses with gastric ulcers

Stomach ulcers hurt. Besides optimizing husbandry, feeding and training systems, you can treat horses with ulcers with certain drugs or support them with supplements. Three types are distinguished here.

1. Stomach acid binders or buffers: also called antacids, are alkaline substances that buffer the acid already present. Buffering means increasing the gastric pH value and thus reducing the stomach's acidity. Another advantage of these buffers is that the feed obtains a better pH-value. This is very important for the further digestion and metabolism in the (small) intestine(s). Equine Gastric 74 belongs to this group.

2. Antacids: e.g. Omeprazole (paste). These have the ability to block and inhibit up to 99% of the acid production. This acid suppressive therapy is known for its ability to treat severe gastric ulceration in all types of horses. The damaged stomach wall is given a chance to regenerate. However, be careful with long-term use of these painkillers and other anti-inflammatory drugs, such as non-steroidal anti-inflammatory drugs (NSAIDs).

3. Gastroprotectants: Form a layer on the mucous membrane, protecting the stomach wall from acid. Sucralfate is a well-known stomach wall protector.

Apart from stomach acid binders, there are natural alternatives to maintain a healthy stomach. To some extent they might even help protect the horse's stomach. Dietary supplements based on pectin and lecithin are especially suitable for this purpose, as they support the natural protective mechanisms of the stomach lining.
Just like flaxseed, which contains a particularly high content of mucilage. Some feeds can also support your horse's ulcer healing.

How quickly does a horse´s stomach heal?

The symptoms of a horse with gastric ulcers should visibly diminish within three to four days when treated with medication. This does not mean the ulcer is cured!

If the ulcer is not completely healed, you often see a relapse as soon as you stop medication. Therefore, it is wise to have another gastroscopy after at least 1 month to check.

Can a horse's ulcer heal by itself?
No, the vast majority of cases do not heal spontaneously. Your horse will need external help treating ulcers, either with medication or natural products.

Preventing stomach ulcers in horses
There are some basic rules, including dietary factors, when it comes to preventing gastric disease. The 5 most important points to prevent gastritis and stomach ulcers in horses:

1. Rest, purity and regularity
   - Give your horses sufficient roughage and avoid feeding breaks longer than 2 hours.
   - Feed low-starch concentrate, divided into several small portions.
   - Feed concentrates after roughage.
   - Provide water of good quality.
2. Provide adequate free movement. Horses are foraging animals.
3. Ensure other horses are visible and your horse has pleasant stable neighbours.
4. Homogeneous herd composition.
5. Adjust the level of training, build in walk-breaks & reduce performance pressure.

Is a gastric ulcer life-threatening for a horse?

A gastric ulcer is not life-threatening from the start, but it can be very painful and can turn dangerous if it is left untreated. In severe, untreated cases an ulcer can lead to heavy internal bleeding or even a perforation of the stomach wall — and at that point it becomes genuinely life-threatening. That's why persistent or worsening signs always warrant a call to your veterinarian rather than waiting it out.

Can you ride a horse with a gastric ulcer?

You can usually still ride a horse with a gastric ulcer, but hard work should be avoided and an acutely painful horse is better off resting. Riding isn't automatically off the table, but it helps to remember that ulcers can be extremely painful and that there is active inflammation inside the stomach. Your horse should still get the chance to move every day for its wellbeing, ideally through turnout, and it's worth checking with your vet whether riding makes sense at all for now.

With an acute ulcer, the pain is often so severe that it's kinder to skip work entirely. Movement makes stomach acid slosh back and forth and reach the raw, injured areas, which is very uncomfortable, so in most cases time off is far more effective for letting the horse and its stomach recover.

Before you start bringing your horse back into work, get the stomach problems and their underlying causes under control first. Then start very gently, because you want your horse to rediscover that work under saddle is enjoyable and not something it associates with stomach pain. Listen to your horse and read its signals: if it would rather hack out, or loosens up far better at the canter than the trot, ride it that way so it stays motivated and willing.

What happens after omeprazole treatment?

After omeprazole treatment, the priority is to fix the underlying causes — feeding and stress — so ulcers don't simply come back. With an ulcer, the point is to address the causes rather than just the symptoms, which usually means adjusting the diet and avoiding or minimizing stress, ideally already during the omeprazole course. Only when there is no longer excess acid sloshing around and attacking the lining can you be confident that new ulcers won't form.

Because most ulcers are stress-related and stress triggers can be hard to switch off, it helps to keep supporting your horse afterward to buffer that stress-related excess acid and protect the stomach. This is where a natural buffer feed like Equine 74 Gastric (available as pellets and powder) fits in: it has a high acid-buffering capacity, so it soaks up the excess stomach acid as one part of ongoing management — not as a medical treatment.

FAQ - gastric ulcers in horses

Sources

• Sykes BW, Hewetson M, Hepburn RJ, Luthersson N, Tamzali Y. European College of Equine Internal Medicine Consensus Statement—Equine Gastric Ulcer Syndrome in Adult Horses. Journal of Veterinary Internal Medicine. 2015;29(5):1288–1299. doi.org/10.1111/jvim.13578
• Vokes J, Lovett A, Sykes B. Equine Gastric Ulcer Syndrome: An Update on Current Knowledge. Animals. 2023;13(7):1261. doi.org/10.3390/ani13071261
• Luthersson N, Nielsen KH, Harris P, Parkin TDH. Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark. Equine Veterinary Journal. 2009;41(7):625–630. doi.org/10.2746/042516409X441929
• Perron B, Ali ABA, Svagerko P, Vernon K. The influence of severity of gastric ulceration on horse behavior and heart rate variability. Journal of Veterinary Behavior. 2023;59:25–29. doi.org/10.1016/j.jveb.2022.11.008

More information

For more on feeding a horse with a sensitive stomach, read our in-depth guide: Which feed for stomach-sensitive horses? It walks you through the right forage, concentrates and supplements to keep your horse's stomach healthy.