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The horse nips as you tighten the girth, is reluctant to go forward, loses coat condition and starts leaving feed. Gastric ulcers can look exactly like that – non-specific and innocuous enough that it is easy to put it down to temperament or to badly fitting tack. Yet gastric ulceration affects as many as 90% of racehorses, 80% of sport horses and 60% of leisure horses.
The key thing is not to guess. Only gastroscopy confirms or rules out the disease, and which form it shows determines both the choice of drugs and the length of treatment. The rest of the work happens at the manger: what counts is the amount of fibre, the length of the gaps between meals and how much cereal is left in the diet.
Update: September 2026. We have added the distinction between ESGD and EGGD, current recommendations for preparing a horse for gastroscopy, omeprazole and sucralfate dosages, and information on supplementation.
- What people call "gastric ulcers" is EGUS, or Equine Gastric Ulcer Syndrome – painful ulceration of the stomach wall and its lining. Today it is separated into two diseases: ESGD in the squamous region and EGGD in the glandular region.
- It affects around 90% of racehorses, 80% of sport horses and 60% of leisure horses, so the at-risk group is far wider than is generally assumed.
- The most common causes are stress, a diet low in fibre, long gaps between meals and limited access to water.
- Signs are often non-specific: loss of appetite, recurrent colic, nipping when the girth is done up, a drop in willingness to work.
- Only gastroscopy confirms or rules out the disease. The examination takes 20–30 minutes, is performed standing under sedation, and the horse must be fasted beforehand.
- Treatment is based on omeprazole, at 4 mg per kilogram of bodyweight once daily, usually for around 28 days in ESGD. EGGD takes longer to treat and is combined with sucralfate.
- Prevention and treatment share the same foundation: constant access to forage and replacing cereals with fibre and oils. Gut-support products and oils back up the diet; they do not replace treatment.
Contents
- Gastric ulcers in horses: what the disease is and how to deal with it
- ESGD and EGGD: two forms of the same disease
- Causes of gastric ulcer disease
- Symptoms of gastric ulcers in horses
- Diagnosis: what examinations are needed
- Treatment of gastric ulcers in horses
- Feeding a horse with gastric ulcers
- Supplements and gut-support products
- Prevention
Gastric ulcers in horses: what the disease is and how to deal with it
Gastric ulcers are extremely common in racehorses, sport horses and leisure horses alike. We talk colloquially about gastric ulcers, but what we are really dealing with is EGUS – Equine Gastric Ulcer Syndrome.
Gastric ulceration affects almost 90% of racehorses, and few owners or competitors realise that sport horses (around 80%) and leisure horses (around 60%) are also in the high-risk group.
Gastric ulcers are painful lesions on the stomach wall and its lining. They can occur in both the glandular and the squamous region of the stomach.
ESGD and EGGD: two forms of the same disease
For years people simply spoke of gastric ulcers. Today equine medicine separates EGUS into two distinct diseases, because they differ in their causes, their course and their treatment.
ESGD (Equine Squamous Gastric Disease) means lesions in the squamous region, where the lining has no natural protection against acid. They arise mainly when acid sits in an empty stomach and splashes up its walls during work. This form responds well to omeprazole.
EGGD (Equine Glandular Gastric Disease) means lesions in the glandular region, which produces the acid and has its own defence mechanisms. Here the culprit is a breakdown of those defences rather than excess acid as such, which is why treatment is harder, takes longer and usually calls for two drugs together.
For the owner the conclusion is simple: without gastroscopy there is no way of knowing which form you are dealing with, and that determines the treatment plan and how long it will take.
Causes of gastric ulcer disease
Ulcers can be brought about by how we manage horses, but not only by that. Understanding the causes lets us reduce the risk by removing some of the factors.
- stress (from competition travel and transport, from a change of surroundings or season, or from unsuitable training),
- an unsuitable diet (low in fibre, too little forage, too much sugar, large meals eaten in a short time),
- limited access to water,
- certain medications (usually anti-inflammatories, phenylbutazone),
- confinement in a box,
- teeth grinding,
- excessively long gaps between meals,
- injury and the pain that comes with it,
- belonging to a high-risk group (genetic factors).
Stress often appears with unsuitable training, and in young horses that are not physically or mentally able to meet what is being asked of them. Stress and agitation also arise around feeding – for instance when it is too slow (some horses in the yard are already eating while others wait) or irregular; keeping to a consistent feeding time matters. Large meals reduce saliva production, and saliva has a real influence on the condition of the digestive tract.
Transport and competition trips are a separate and often underrated factor. We wrote about how to reduce a horse's stress in those situations in our guide on how to transport a horse safely.
Horses frequently develop Equine Gastric Ulcer Syndrome when they do not have constant access to forage and water. Giving hay in small portions can leave a gap of several hours with nothing to eat. Long gaps mean gastric acid irritating the sensitive walls of the horse's stomach.
Confinement in a box, ongoing pain and boredom can also stress and unsettle a horse considerably, which increases hydrochloric acid secretion. Frustration in the same way feeds through to the horse's health and puts it at risk of EGUS.
Symptoms of gastric ulcers in horses
An attentive owner can spot the signs of stomach pain fairly quickly, but bear in mind that in the early stages the pain and the signs may not be noticeable at all. That is why regular examinations matter, all the more so if you know your horse is exposed to any of the factors listed above.
- loss of appetite, leaving feed,
- painful, recurrent colic,
- reluctance to go forward, a drop in energy and willingness to work,
- poor coat condition, a dull coat,
- frequent, recurrent diarrhoea,
- nipping when the girth is tightened,
- sensitivity when the belly area is touched or groomed,
- apathy,
- weight loss,
- difficulty passing urine,
- the flehmen response (repeatedly curling the upper lip as a sign of pain),
- crib-biting,
- a change in water intake (it may go up or down),
- lying down frequently,
- teeth grinding.
Some of these signals – particularly nipping at the girth and reluctance to work – are easily confused with back pain or badly fitting tack. It is worth knowing the ridden horse pain ethogram and checking the saddle fit before you consider the matter closed.
If you notice any worrying signs, consult your vet.
Diagnosis: what examinations are needed
Gastric ulcer disease can only be confirmed or ruled out by gastroscopy. The procedure is performed standing, under sedation rather than general anaesthesia, and it is safe and painless for the horse. The examination itself takes about 20–30 minutes, while preparing the horse takes well over a dozen hours.
A few things need to be done so the horse can be fully examined and you get complete information about its condition.
- current guidance is that the horse should not eat for 12–16 hours before the examination – ask your vet for the exact time,
- water is usually withdrawn 2–4 hours beforehand; the simplest approach is to turn off the automatic drinker in the box,
- leave a muzzle on during the fast so the horse cannot pick up anything to eat. There are even cases of horses eating their own droppings while fasted.
Make sure the horse has an empty box with no bedding or hay at all, and turn off the drinker a few hours before the examination. Do not turn the horse out, and it is worth telling everyone at the yard not to give it treats or feed.
It is a good idea to book the gastroscopy for the morning – that way the fast falls overnight, while the horse is resting and sleeping.
Treatment of gastric ulcers in horses
Once the vet has confirmed gastric ulcers, medical treatment should start as soon as possible and the prescribed doses should be followed exactly.
What does treating a horse with ulcers actually involve?
The diet should be as fibre-rich as possible, to buffer the effect of gastric acid on the stomach wall. The medication is there above all to reduce acid secretion so that the stomach lining can heal.
As things settle down in the stomach, the signs of pain and the inflammation of the stomach wall should gradually subside.
The main active substance is omeprazole, available as pastes and sachets. The standard therapeutic dose is 4 mg per kilogram of bodyweight once daily, and treatment for the squamous form lasts around 28 days. Omeprazole is given on an empty stomach, at least half an hour before feeding, because that is the only way it works as it should. It sits at the upper end of the price range and availability in Poland varies, so it is worth asking your vet for a prescription covering the whole course.
Alongside omeprazole it matters to support treatment with something that protects the stomach lining. Ulgastran, that is sucralfate, soothes the stomach wall and shields it from the excessive action of acid. For the glandular form this is no longer an optional extra but the standard: omeprazole combined with sucralfate is recommended, treatment runs beyond four weeks and is sometimes repeated after a follow-up gastroscopy.
Diet also plays an enormous part in gastric ulcer disease. The right diet combined with medical treatment delivers the results you want, and the treatment time can be shortened considerably if you follow the rules and your vet's instructions.
It is worth adding that an ulcer diet can also be fed to horses with no stomach problems – in which case it serves as prevention.
Feeding a horse with gastric ulcers
Forage and fibre
The foundation of a good diet for horses with ulcers is fibre, which limits the action of gastric acid.
The absolute basis of feeding is making sure the horse has forage.
Guidance calls for a minimum of 1.5 kg of forage dry matter per 100 kg of bodyweight per day, which for a 500 kg horse means at least 7.5 kg of hay on a dry matter basis. Pay particular attention to the horse's nature. For most of the day horses are occupied with taking in small amounts of food, which is why unrestricted access to hay and other forage is a necessary condition. Not only when you are dealing with a horse with ulcers, but throughout the diet of racehorses, sport horses and leisure horses alike.
Oils
With gastric ulcer disease it is advisable – in fact necessary – to drop cereal feeds. Oats, barley and other grains contain no fibrous structure, but they do contain starch, which in excess lowers the pH in the stomach and hindgut. The accepted upper limits are 2 g of starch per kilogram of bodyweight per day and 1 g per meal.
Taking certain products out of the diet, cereals included, reduces the energy the feed provides, and it is oils that will give your horse that energy back during treatment.
Horses with ulcer disease benefit from oils such as linseed or black cumin, though remember to introduce them gradually. Instead of litres of raw oil you can reach for Over Horse Omega 3+6+9, a concentrated linseed oil extract in which omega-3 makes up more than half the composition. The dose for a horse of around 550 kg is 50 ml a day mixed into the concentrate feed, so a two-litre container lasts forty days. Keep the oil in a dark place and use it within about three months of opening, because unsaturated fats oxidise quickly.
If your horse is going through, or has just finished, a long course of medication, milk thistle oil is often given alongside linseed oil – cold-pressed and added to the concentrate feed at 50–150 ml daily.
Mash or linseed
Preparing linseed releases a mucilage that has a protective effect on the stomach lining. A good mash always contains linseed, which is exactly what you want in the diet so that gastric acid does not irritate the stomach wall.
In its mildest stage ulceration may amount to no more than slight reddening, but it can equally be extremely painful open lesions – which is why using products that limit the action of acid matters.
Instead of a mash you can give beet pulp and prepared linseed, but discuss any changes and ideas with your vet or a nutritionist.
Small portions
For the digestive tract to settle, the recommended ration should be given in small portions.
Small portions limit excessive acid production. At least six hours should pass between concentrate feeds. You can give more, smaller meals across the day to provide the daily allowance of vitamins and minerals. A single portion should not exceed 1 g per kilogram of bodyweight, which in practice works out at 0.5–0.7 kg depending on the horse's size and weight.
Supplements and gut-support products
Diet does most of the work, but during treatment and after it the horse's stomach usually gets some additional support. This means plant and mineral products that coat the lining and soften the action of acid – not another drug.
Over Horse Gastro Protect is a complementary feed in granulate form built from nine ingredients: sea buckthorn, alfalfa, marigold, marshmallow, ribwort plantain, comfrey, nettle, chamomile and calcium carbonate. The mucilaginous plants coat the lining while the calcium carbonate buffers acid. The dose for a horse of around 550 kg is 50 g morning and evening, that is 100 g a day, so a 3 kg container covers a month.
There is deliberately no liquorice in the composition, although it appears in some stomach products. Used for longer than three or four weeks, liquorice promotes sodium and water retention and potassium loss, which matters in horses with metabolic disorders and alongside diuretics or steroids.
No gut-support product is a medicine, and none will replace gastroscopy or the treatment your vet prescribes. Supplementation makes sense as a back-up to treatment and as prevention once treatment is finished. Combining products with medication is the vet's decision, and in pregnant and lactating mares consultation is obligatory.
It is also worth remembering hydration and replacing what the horse loses in sweat during work and travel. Electrolytes have nothing to do with treating ulcers, but a horse that drinks willingly and regularly has calmer conditions in its stomach than a dehydrated one.
Prevention
In prevention, just as in treatment, providing a fibre-rich diet is what matters most, which is why it is worth giving the horse two or three handfuls of chaff before you ride. The chaff tops up the stomach contents, so acid will not splash up the stomach walls while you work.
In horses in hard work or travelling, a vet may recommend omeprazole at a preventive dose of 1 mg per kilogram of bodyweight – but that is the vet's decision, not something to use off your own bat.
It is worth dropping cereal feeds and giving the horse something that limits hydrochloric acid production instead. Hydrochloric acid causes horses considerable discomfort, comparable to heartburn.
In the diet of horses with ulcers – for example once the ulcers have healed and medication has stopped – aim for feeds that are high in energy, low in starch and low in sugar. Swap cereals for oils and adjust the ration to a nutritionist's recommendations.
One last thing that is easy to forget while focusing on diet: if your horse nips at the girth or is reluctant to go forward, check the tack too. A badly fitting saddle and an over-tight girth produce similar signs, and a saddle fitter will help with the fit.
You can put together your horse's diet and supplementation from the feed and supplements section, and if you need help choosing, write to kontakt@equishop.com or call +48 32 782 45 68. You are also welcome at our shop and service centre at ul. Oświęcimska 9 in Ruda Śląska, Monday to Friday, 9:00–17:00.
