Equine Gastric Ulcer Syndrome (EGUS): What Every Horse Owner Needs to Know

Equine Gastric Ulcer Syndrome (EGUS) is one of the most discussed health conditions in the horse world. Yet despite increased awareness, it remains widely misunderstood. Many owners associate gastric ulcers with poor performance, grumpy behaviour or stressy competition horses, but the reality is that they can affect horses of all ages, breeds and disciplines.

Gastric ulcers are far more common than many owners realise. Whilst prevalence is highest in racehorses and elite athletes, studies have found that even leisure horses can be affected, often without displaying obvious clinical signs. British Equestrian's Equine Health Week 2026 specifically highlighted that equine gastric ulcer syndrome is believed to affect as many as one in three horses in the UK.

Understanding what EGUS is, how it develops, and what role management, nutrition and veterinary intervention play can help horse owners make informed decisions and support long-term digestive health.

What Is Equine Gastric Ulcer Syndrome?

Equine Gastric Ulcer Syndrome is an umbrella term used to describe ulceration within the horse's stomach. The equine stomach is divided into two distinct regions:

• The squamous (upper) region
• The glandular (lower) region

These areas have very different functions and protective mechanisms.

The lower glandular region naturally produces mucus, bicarbonate and other protective substances to defend itself against stomach acid. Saliva (which is produced only whilst chewing) adds additional buffering bicarbonate to the stomach which is why it is so important that horses have near constant access to forage. The upper squamous region has no such protection and is therefore much more vulnerable to acid exposure.

Unlike humans, horses produce stomach acid continuously, whether they are eating or not. In a natural environment, horses spend up to 18 hours per day grazing, with a near-constant supply of forage helping to buffer stomach acid naturally and maintain a healthy gastric environment.

Modern management can disrupt this natural system. Periods without forage, intense exercise, travel, competition, restricted turnout and routine changes can all increase the risk of gastric ulceration developing.

What Causes Gastric Ulcers in Horses?

Ulcers occur when the protective mechanisms within the stomach become overwhelmed or when the delicate stomach lining is repeatedly exposed to acid and digestive enzymes.

This can happen for several reasons:

• Long periods without forage
• High concentrate or starch-rich diets
• Intensive exercise
• Travel and competition schedules
• Stress and routine changes
• Illness or pain elsewhere in the body
• Use of certain medications under veterinary direction

During exercise, the acidic contents of the stomach can splash upwards onto the more vulnerable squamous region. Combined with reduced forage intake and increased stress, this creates the ideal environment for ulceration to occur.

Importantly, ulcers rarely develop because of one single factor. More commonly they are the result of multiple management, dietary and environmental stressors accumulating over time.

The Signs of Gastric Ulcers in Horses that Owners Often Miss

One of the biggest challenges with EGUS is that many horses do not display the textbook signs owners expect. Whilst some horses may become obviously uncomfortable, others show only subtle changes that are easy to dismiss as temperament, training issues or seasonal fluctuations.

Common signs include:

• Changes in attitude or behaviour
• Reduced appetite
• Becoming "girthy"
• Sensitivity when grooming
• Reluctance to go forward
• Poor focus during work
• Reduced performance
• Weight loss or difficulty maintaining condition
• Intermittent loose droppings
• Dull coat condition
• Increased stress or anxiety

Many of these signs overlap with other digestive concerns, particularly those involving the hindgut, which is why it is so important to view digestive health as a whole rather than focusing solely on the stomach. The gut functions as an interconnected system, and changes in one area can influence another.

If you haven't already, we recommend reading our article on the importance of gut health in horses, which explores how digestive function can influence behaviour, condition, performance and overall wellbeing.

Gastric Ulcers vs Hindgut Ulcers: What's the Difference?

The terms "gastric ulcers" and "hindgut ulcers" are often used interchangeably, but they refer to different parts of the digestive tract.

Gastric Ulcers

These occur within the stomach and fall under the diagnosis of Equine Gastric Ulcer Syndrome (EGUS).

They can affect:

• The squamous region
• The glandular region
• Both regions simultaneously

Gastroscopy remains the gold standard for diagnosis.

Hindgut Ulcers

Hindgut ulceration occurs further down the digestive tract, typically within the caecum or colon.

Unlike gastric ulcers, hindgut ulceration is much more difficult to diagnose definitively as it cannot be seen using a gastroscope and often requires a broader assessment of symptoms, history and veterinary investigation.

Common signs associated with hindgut dysfunction may include:

• Loose droppings
• Faecal water
• Poor condition
• Behavioural changes
• Recurrent digestive upset
• Poor performance

Whilst the stomach and hindgut are different environments, many of the risk factors overlap. Stress, dietary inconsistency, sudden feed changes and management challenges can all place pressure on the digestive system as a whole.

When Should You Seek Veterinary Help?

Not every horse displaying digestive discomfort has ulcers. Equally, not every ulcerated horse will display obvious symptoms.

If your horse is showing persistent changes in behaviour, appetite, performance or condition, veterinary investigation is always the best place to start.

Seek veterinary advice if your horse:

• Has persistent or worsening symptoms
• Experiences unexplained weight loss
• Shows signs of pain or discomfort
• Has recurrent episodes despite management changes
• Is performing significantly below expectations
• Has previously been diagnosed with ulcers

A veterinarian can determine whether further investigation such as gastroscopy is appropriate and recommend treatment where necessary.

Nutritional support can play an important role in maintaining digestive health, but it should not replace veterinary diagnosis where significant clinical signs are present.

The Role of Diet, Management and Consistency in Gastric Health

One of the most important things horse owners can understand is that digestive health is rarely solved by supplements alone. Supplements cannot (and should not) claim to treat ulcers or any other medical condition, doing so is a breach of the regulations by making medicinal claims. Using quality supplements for ulcer prone horses can be beneficial in helping to maintain a healthy gastric environment and provide antioxidants to support against the oxidative stress that occurs on a day-to-day basis.

The horses that tend to maintain the healthiest digestive systems are usually those where the fundamentals are consistently managed well, not just fed a supplement in isolation.

Key principles include:

Maximise Forage Availability

Forage helps maintain normal digestive function and provides a natural buffering effect within the stomach through the production of saliva whilst chewing.

Avoiding long periods without forage is one of the simplest ways to support optimal gastric health.

Introduce Changes Gradually

The digestive system thrives on consistency.

Whether changing feed, forage, turnout or routine, gradual transitions allow the microbiome and digestive tract time to adapt.

Consider Stressors

Travel, competitions, changes in herd dynamics, box rest and seasonal management changes all place additional pressure on the digestive system.

Being proactive during these periods can often be beneficial; offer a variety of forages to tempt them to eat, split bucket feeds into multiple meals with added fibre and consider the use of calming supplements for horses who are particularly stressy.

Support the Whole Gut

Whilst gastric health receives a great deal of attention, the hindgut plays a fundamental role in digestion, nutrient absorption and overall wellbeing.

Supporting microbial diversity and maintaining a resilient hindgut environment may help horses cope better with inevitable management and environmental challenges. The microbiome requires a variety of prebiotic fibres to thrive, so adding a hindgut supplement to feed the good bacteria will support optimal production of postbiotics in the hindgut which in turn helps maintain gut lining integrity.

Focus on Consistency

Perhaps the most overlooked factor of all is consistency. The digestive system responds best to stable routines, consistent forage intake and long-term management rather than short-term fixes.

Whether your goal is maintaining gastric comfort, supporting the microbiome or managing seasonal changes, consistency is often what delivers the greatest long-term results. Quality forage should be the basis of all diets, whilst supplements can play an important supportive role to correct management.

The Bottom Line

Equine Gastric Ulcer Syndrome is common, but it is only one piece of the digestive health puzzle.

Understanding how ulcers develop, recognising the subtle signs and appreciating the difference between gastric and hindgut health can help owners make better decisions for their horses. Whilst veterinary diagnosis remains essential where significant symptoms are present, management, nutrition and consistency all play a powerful role in supporting long-term digestive wellbeing.

Because ultimately, digestive health isn't simply just about preventing problems, it is about creating an environment where the entire digestive system can function as it was designed to – with a near constant supply of diverse forage - every single day. Remember that horses in the wild consume over 40 different plant species each day so we must do our best to top up that variety that horses in modern management often lack and support overall digestive health.

 

FAQ’s

What are the signs of ulcers in horses?

The signs of gastric ulcers can vary considerably between horses and are often subtle. Common signs include reduced appetite, becoming "girthy", sensitivity during grooming, behavioural changes, poor performance, weight loss, difficulty maintaining condition and a reluctance to work. Some horses may also appear more anxious or reactive than usual. Because these signs can overlap with other health conditions, veterinary investigation is recommended if symptoms persist.

Can horses get ulcers on grass?

Yes. Whilst continuous access to grazing is generally considered beneficial for gastric health, horses living at grass can still develop ulcers. Factors such as stress, social dynamics, restricted forage intake, intensive exercise, travel, illness or pain elsewhere in the body can all contribute to ulcer development. Ulcers are rarely caused by a single factor and are often the result of multiple stressors occurring simultaneously.

What causes gastric ulcers in horses?

Gastric ulcers develop when the stomach lining is repeatedly exposed to stomach acid and the stomach's natural protective mechanisms become compromised. Common risk factors include long periods without forage, high-starch diets, intensive exercise, travel, competition, routine changes and stress. Unlike humans, horses produce stomach acid continuously, making regular access to forage particularly important for maintaining a healthy gastric environment.

What is the difference between gastric and hindgut ulcers?

Gastric ulcers occur within the stomach and fall under the diagnosis of Equine Gastric Ulcer Syndrome (EGUS). Hindgut ulcers occur further down the digestive tract, typically within the caecum or colon. Whilst both can affect a horse's comfort, behaviour and performance, they involve different parts of the digestive system and may require different management approaches. Many of the risk factors overlap, including stress, dietary changes and management practices.

Can nutrition support horses prone to ulcers?

Nutrition can play an important role in supporting digestive health and maintaining a healthy gastric environment, particularly when combined with appropriate management practices. Consistent access to forage, careful dietary management and targeted nutritional support may help horses cope with the challenges associated with training, travel and routine changes. However, nutrition should not replace veterinary diagnosis or treatment where gastric ulceration is suspected.

The Equell Team - 10th June 2026