EGUS in Horses: Understanding and Managing Equine Gastric Ulcer Syndrome

Understanding Equine Gastric Ulcer Syndrome (EGUS): Causes, Symptoms, and Long-Term Support

Equine Gastric Ulcer Syndrome, commonly referred to as EGUS, is a widespread condition that affects horses of all disciplines and backgrounds. Characterized by lesions or erosions in the stomach lining, EGUS can cause significant discomfort and performance issues. Understanding its causes, identifying symptoms early, and adopting a comprehensive support strategy are key to managing this condition—especially in performance horses who live under high-stress conditions.

What Is EGUS?

EGUS encompasses a range of ulcerative conditions in the horse’s stomach. The equine stomach is divided into two distinct regions: the non-glandular (squamous) and the glandular mucosa. Ulcers can occur in either or both sections, although they are more common in the squamous region, which lacks the protective secretions found in the glandular part.

The cause is primarily an imbalance between aggressive factors (like gastric acid) and the protective mechanisms of the stomach lining. Horses secrete stomach acid continuously—even when they are not eating—which makes them particularly vulnerable to mucosal injury if management practices aren’t optimal.

Who Is at Risk?

Although any horse can develop gastric ulcers, some are at significantly higher risk:

• Racehorses and sport horses: Studies show that between 53% and 93% of racehorses have some degree of gastric ulceration.
• Horses in intense training: Exercise increases intra-abdominal pressure, pushing acid into the squamous region.
• Horses with limited turnout or forage access: Constant access to roughage helps buffer stomach acid. Without it, acid builds up and damages the stomach lining.
• Horses exposed to stress: Transport, competition, social changes, and changes in routine can all affect gastric health.

Common Symptoms of EGUS

The signs of EGUS can range from subtle to obvious. In many cases, owners may notice only behavioral changes or reduced performance. Common symptoms include:

• Decreased appetite or picky eating
• Weight loss or failure to gain weight
• Mild, recurring colic signs
• Irritability or behavioral changes
• Poor coat condition
• Discomfort when saddled or ridden
• Repeated yawning or teeth grinding
• Soft or inconsistent manure

These signs often overlap with other conditions, so proper diagnosis is essential.

Diagnosis: How Are Ulcers Confirmed?

The most reliable method for diagnosing gastric ulcers in horses is gastroscopy. This procedure involves passing a flexible endoscope through the horse’s nostril, down the esophagus, and into the stomach. The stomach lining is then visually inspected for signs of lesions, erosions, or inflammation.

Gastroscopy requires the horse to be fasted for at least 12 hours to ensure a clear view. While other diagnostic tools like bloodwork or fecal testing may be used to rule out other issues, only gastroscopy can confirm EGUS.

Why Do Ulcers Develop? The Multifactorial Nature of EGUS

There is no single cause of EGUS. Instead, multiple factors often interact:

Feeding Practices

• Long periods without forage reduce saliva production, which is essential for buffering stomach acid.
• Diets high in concentrates and low in fiber increase acid production.

Physical and Psychological Stress

• Exercise and competition heighten acid production and reduce gastric blood flow.
• Changes in environment, herd structure, or management routines elevate stress levels.

Medication Use

• Non-steroidal anti-inflammatory drugs (NSAIDs) can reduce protective mucus production.

Illness and Parasites

• Systemic illness or heavy parasite load can compromise mucosal integrity.

Housing Conditions

• Stall-bound horses have a higher risk due to reduced movement and feeding frequency.

Treatment: Pharmaceutical and Beyond

The cornerstone of ulcer treatment is omeprazole, a proton pump inhibitor that reduces acid secretion. In severe cases, additional medications like sucralfate may be used to coat the stomach lining and aid healing.

However, medication alone is not enough. A holistic approach is critical:

• Dietary Changes: Feed smaller, more frequent meals. Increase fiber and reduce starch.
• Management: Increase turnout and reduce unnecessary stressors.
• Monitoring: Recheck via gastroscopy after treatment to confirm healing.

After the Ulcers Heal: Long-Term Maintenance

Once ulcers have resolved, it’s essential to prevent recurrence, especially in horses that remain in high-stress environments. This is where long-term strategies—including the use of dietary supplements—come into play.

The Role of Hyaluronic Acid in Gastric Support

One of the most promising natural compounds in gastric support is hyaluronic acid (HA). Traditionally known for its role in joint health and skincare, HA is now being explored for its gastrointestinal benefits, particularly in maintaining and repairing the mucosal barrier.

In the stomach, hyaluronic acid can:

• Form a mucoadhesive film that protects the mucosa from acid damage
• Help retain moisture and support tissue elasticity
• Potentially modulate immune responses that are involved in mucosal healing

These effects make HA a suitable candidate for ongoing support—especially in horses that cannot live on pasture or must continue training and traveling.

Gelled HA: Why Formulation Matters

Not all HA supplements are equal. Gelled or matrix-bound forms of HA, especially those combined with alginates (plant-based polysaccharides), have shown improved adhesion to the gastric lining and longer retention time.

This extended contact time may:

• Offer a prolonged buffering effect
• Support better recovery post-treatment
• Enhance mucosal hydration and protection even during acid surges

EGUS and Real-Life Constraints: Why Prevention Matters

While pasture turnout and 24/7 grazing are ideal, they’re not realistic for many sport horses. Competition schedules, training requirements, and transportation needs introduce unavoidable stressors.

In these cases, prevention is key. Regular use of targeted supplements—like gelled hyaluronic acid—can serve as a protective buffer for horses that remain at risk.

Owners and trainers should work proactively:

• Administer HA before and after known stressors (e.g. competitions, travel)
• Maintain a high-forage diet with frequent access to hay
• Monitor behavior and appetite closely

Final Thoughts

Equine gastric ulcers are a complex but manageable condition. Early identification, correct treatment, and sustained prevention strategies make a significant difference in a horse’s well-being and performance.

Hyaluronic acid—especially in advanced formulations—offers a promising avenue for non-pharmaceutical, long-term support. As our understanding of EGUS grows, incorporating such ingredients into daily care regimens could be the key to maintaining gastric health in horses that face modern demands.

As always, any supplementation or management changes should be discussed with a qualified veterinarian. EGUS may be common, but with the right approach, it doesn’t have to be chronic.