Gastric Ulcers in Horses

Why the stomach lining can be damaged, why signs are easy to miss and how vets confirm and manage ulcers.

Quick Answer

Gastric ulcers are lesions in the stomach lining that can be mild or severe, and they can affect horses of all ages and types, not only competition horses.
Signs are often vague, such as weight loss, poor performance, girthiness or reduced appetite, and some horses show none at all.
Signs alone cannot confirm ulcers because other problems, such as back pain, can look the same, and only a gastroscopy can reliably diagnose them.
Colic-type signs need an urgent call to your vet, because they may be a colic emergency.
Treatment is directed by your vet and works best alongside changes to feeding, turnout and stress, and stopping too soon can lead to relapse.

Gastric ulcers in horses are lesions to the stomach lining, and they can be mild or severe. The term equine gastric ulcer syndrome (EGUS) is used to describe lesions, ulcerations and erosions in the horse's digestive tract.

Ulcers can be common in horses of different breeds, ages and types, and foals are also very susceptible. They are particularly talked about in racehorses and elite competition horses, but any horse can have them, especially with limited access to forage.

Close-up of a chestnut horse with its head lowered into hay against an evening sky – steady access to forage matters for gastric ulcers in horses

How Gastric Ulcers in Horses Develop

Two types of stomach disease

Vets recognise two main types, named for the part of the stomach affected. Equine squamous gastric disease (ESGD) affects the upper part, and equine glandular gastric disease (EGGD) affects the lower part. They are related but distinct conditions, each with its own causes and treatment.

The upper part of the stomach does not make acid or mucus. The lower part makes acid and enzymes and is protected by a thick layer of mucus.

Squamous ulcers are the most commonly diagnosed form and occur when there is too much acid in the stomach. In glandular disease the stomach's own protective barrier fails, exposing the lining to acid. The cause of glandular disease is not fully understood.

A stomach built for constant grazing

Horses have evolved to trickle feed for many hours a day. Their stomachs make a steady flow of acid throughout the day, even when the horse is not eating.

In the wild the stomach is almost constantly filled with forage. Chewing also produces saliva, which contains bicarbonate that reduces acidity. A horse's stomach is also small for its size.

Causes and Risk Factors

Several factors can contribute to gastric ulcers in horses, and they often overlap.

Long gaps without forage

When forage is not readily available, for example during stabled periods, exercise or transport, excess acid can "splash" onto the upper lining of the stomach. High-concentrate feeds with little forage make the stomach more acidic still.

Two horses, one dark bay and one chestnut, eating hay from a metal hay feeder in a paddock – regular forage is part of preventing gastric ulcers in horses

Exercise and stress

Fast work, especially on an empty stomach, increases acid splashing and damage to the upper stomach. Stress is also a risk factor. This includes intensive exercise, travel, limited interaction with other horses and restricted turnout.

Ulcers are not only a stabled-horse problem. A UK horse magazine reported research showing that even feral ponies living on the moors can develop ulcers, although it was unclear whether they had them all along or developed them shortly before the samples were taken.

Long-term anti-inflammatory painkillers

Prolonged use of anti-inflammatory painkillers (NSAIDs) is a risk factor, especially for glandular disease. However, one vet practice points out that these drugs are generally quite safe at the recommended doses and that withholding them may cause more pain. Do not stop painkillers on your own. Ask your vet about pain relief if ulcers are a concern.

Signs That May Be Linked to Ulcers

Some horses make it very clear that they are uncomfortable. Others show no signs at all because of their natural stoic behaviour. Possible signs include:

Weight loss or a loss of coat condition
A dull, depressed manner, or reduced performance
Resistance to aids or the leg when ridden
Grumpy or aggressive behaviour when girthing, rugging or grooming
Reduced appetite, or discomfort after a hard feed
Colic-type signs
Teeth grinding, crib biting or windsucking
Chronic diarrhoea, which is most common in foals

Squamous ulcers are typically linked with poor performance, intermittent low-grade colic and behaviour changes such as girthiness. Glandular signs can be very vague, and are usually too vague to diagnose from.

This is why you should never assume ulcers from signs alone. Ulcer signs can look nearly identical to back pain when a horse is ridden, and poor performance can also have an orthopaedic cause. Equally, some horses with ulcers show no signs, so look at the whole horse.

Emergency: Contact a Vet Immediately If…

Your horse shows colic-type signs. Treat it as a possible colic emergency.
A foal shows colic-type signs. In severe cases ulcers can perforate the stomach, which can be fatal, and this is more common in foals than in adult horses.

Call your vet or the nearest out-of-hours emergency vet straight away. Our Signs of Colic in Horses guide explains what to look for.

When to Contact Your Vet

Your horse has lost its appetite or is losing weight. Why Won't My Horse Eat? covers other possible causes.
Your horse has poor performance, behaviour changes or recurring mild colic, as these may be linked to ulcers.
Your horse has been given long-term painkillers and you are worried about ulcers. Do not stop them without talking to your vet.

A horse that stops eating, or shows colic signs, needs prompt advice. Please do not try to treat suspected ulcers at home.

How Vets Diagnose Ulcers

The only reliable way to diagnose gastric ulcers is a gastroscopy. A vet passes a camera on a long, flexible tube up the horse's nose, down the oesophagus and into the stomach. The horse is sedated, and the procedure is normally fairly pain-free and well tolerated.

The stomach needs to be empty so the vet can see clearly. Fasting practice varies, so your vet will give you instructions on how to prepare your horse.

The vet can see whether ulcers are present, which region they are in and how severe they are. This helps to plan treatment. It is a relatively safe procedure, and the main risk is mild colic afterwards.

Gastroscopy can be done at the clinic or on your yard. It is also used to monitor how well treatment is working. Occasionally a biopsy is needed, usually when there is a poor response to treatment.

For glandular disease, signs cannot be used to diagnose it, so gastroscopy is used to assess the lesions and how well treatment is working. A study at a UK equine hospital also found limited agreement between specialist vets when grading glandular lesions, which shows how hard these lesions can be to describe.

Treatment and Management

Veterinary treatment

For severe cases your vet may prescribe medicine that reduces stomach acid, which gives damaged tissue time to heal. Treatment depends on the type. Squamous ulcers respond mainly to acid-reducing medicine, whereas glandular ulcers often need a different or additional approach, such as a medicine that protects the stomach lining.

Courses are usually at least a month. One practice says most cases need 4 to 12 weeks. A repeat gastroscopy checks that the stomach is healing.

A horse may look better before its stomach has fully healed, so stopping treatment too soon can cause relapse. Always follow your vet's advice. Without dealing with predisposing factors such as pain, feed issues or stress, the success of treatment is limited.

Outlook

In most cases a good outcome is expected. Some cases, most likely glandular ones, do not fully respond and need ongoing management. Treatment can be drawn out and expensive.

What about supplements?

Vets' views differ. One vet adviser to a UK horse magazine says that a variety of supplements, including fibrous, protein, seaweed, plant and mineral ones, have not been proven clinically effective in treating or preventing squamous ulcers. Another vet practice says a supplement may be used alongside medical treatment. Ask your vet before relying on any product.

Passports, records and competition

In the UK, horses are classed as food-producing animals, and the passport declaration decides which medicines can be given. A vet must ask to see the passport unless they already know its status. If you compete under British Equestrian rules, most medicines and drugs are prohibited if detected in a horse at the time of competition. Keep dated records of treatment and ask your vet.

Preventing Gastric Ulcers in Horses

Management changes are a key part of both prevention and recovery. Your vet or a nutritionist can tailor them to your horse.

Give as much turnout as possible. Turnout alone does not always fix ulcers, because there must be enough grass cover.
Provide forage throughout stabled periods and avoid long gaps. Small-holed hay nets or slow feeders can slow intake.
Feed hay or chaff about 30 minutes before exercise, as it acts as a "raft" that reduces acid splashing.
If your horse needs concentrate feed, split it into as many meals as possible and speak to a nutritionist.
Reduce stress wherever possible and learn your horse's triggers.
Change diets gradually, over a minimum of 10 to 14 days.
Monitor weight and behaviour for sudden changes.

Horses on a controlled diet still need a steady supply of forage. Ask your vet how to manage calories without long gaps without food. Our guides to Equine Metabolic Syndrome (EMS) in Horses and Is My Horse Overweight? explain more.

How Pet Med Direct Can Help

Suspected ulcers need a vet's assessment first. Please do not buy products to treat ulcers before your vet has examined your horse.

If your vet advises products as part of your horse's care, you can browse our equine range.

Some pet medicines require a valid veterinary prescription. Pet Med Direct can only supply prescription medicines after the prescription has been checked. Always follow your vet's advice and the directions on the medicine label.

Frequently Asked Questions

Can I tell if my horse has gastric ulcers from the signs?

No. Signs overlap with other problems, such as back pain, and some horses show none. Only a gastroscopy can reliably confirm ulcers, so speak to your vet.

Can a field-kept horse get ulcers?

Yes. Gastric ulcers in horses kept at grass are possible, because stress, exercise and travel all matter, and research reported by a UK horse magazine found ulcers even in feral ponies on the moors. Good turnout helps, but there needs to be enough grass cover.

Does feeding forage before exercise help?

The British Horse Society and a UK vet clinic both recommend feeding hay or chaff before exercise. It acts as a raft that reduces acid splashing. Ask your vet what suits your horse.

How long does ulcer treatment take?

Courses are usually at least a month, and some practices say 4 to 12 weeks. A repeat gastroscopy checks healing. Stopping early can cause relapse, so follow your vet's plan.

Should I stop my horse's painkillers if I worry about ulcers?

No, not without talking to your vet. Withholding painkillers may cause more pain, and your vet can recommend suitable options.

Related Equine Health Guides

Sources and Further Reading

This article was researched from the sources listed above. It is general information for horse owners and is not a substitute for advice from your own vet.

Prefer Pet Med Direct in Google Search

Choose Pet Med Direct as a preferred source on Google to help you find more of our pet health, medicine and prescription information in Google Search.

← Back to Equine Health Hub

Need pet products or prescription medicines? Visit the Pet Med Direct shop.

Shop Pet Med Direct

This article is for informational purposes only and does not constitute veterinary advice.
If you are concerned about your horse’s health, please consult a qualified veterinarian.