Signs of Gastric Ulcers in Horses — and How to Prevent Them Naturally

Gastric ulcers are one of the most common and most underdiagnosed health issues in horses. Studies estimate that up to 90% of racehorses and 60% of all horses in regular work are affected — yet many owners never recognise the signs until the condition becomes serious.

This guide covers everything you need to know: how to spot the warning signs, what causes gastric ulcers, and how nutrition and supplementation can help prevent them.

What Are Equine Gastric Ulcers?

The horse's stomach is divided into two regions: the upper squamous mucosa and the lower glandular mucosa. Unlike the glandular region, which produces a protective mucus layer, the squamous mucosa has no natural protection against stomach acid — making it highly vulnerable to ulceration.

The European College of Equine Internal Medicine (ECEIM) distinguishes between two conditions:

ESGD (Equine Squamous Gastric Disease) — ulcers in the upper, unprotected part of the stomach, closely linked to management factors like diet and exercise

EGGD (Equine Glandular Gastric Disease) — ulcers in the lower, glandular region, more associated with stress and immune response

Both conditions can occur simultaneously and require different management approaches.

10 Signs Your Horse May Have Gastric Ulcers

One of the most challenging aspects of EGUS is that many horses show no obvious signs at all — or the signs are subtle enough to be mistaken for attitude or training issues. Here are the most common indicators to watch for:

1. Girthiness Resistance or discomfort when tightening the girth is one of the most reported signs. In one study, 92% of horses displaying girthiness were found to have gastric ulcers on gastroscopy.

2. Recurrent mild colic Intermittent, low-grade colic — particularly after feeding or during periods of fasting — is a classic sign of gastric discomfort.

3. Poor appetite or slow eating Horses with ulcers may eat reluctantly, leave feed, or show a preference for hay over concentrate — because roughage buffers stomach acid while concentrates can worsen irritation.

4. Weight loss and poor body condition Chronic discomfort reduces feed intake and nutrient absorption, leading to gradual weight loss that can be easily overlooked.

5. Dull coat A lack-lustre coat that doesn't respond to improved feeding is often a sign of underlying digestive issues.

6. Behavioural changes Increased sensitivity, irritability, resistance to being ridden, bucking, or rearing — especially when pressure is applied to the girth area — can all be linked to gastric pain.

7. Teeth grinding (bruxism) Grinding teeth, particularly around feeding time, is a sign of nausea or gastric discomfort.

8. Reduced performance Unexplained drops in performance, reluctance to work, or loss of focus and energy are common — and frequently attributed to training or temperament issues rather than stomach health.

9. Frequent stretching Horses may repeatedly stretch out as if trying to urinate — a sign of abdominal discomfort.

10. Loose droppings or diarrhoea Digestive upset from gastric inflammation can affect the entire gastrointestinal tract, resulting in inconsistent or loose manure.

What Causes Gastric Ulcers in Horses?

The horse's stomach produces acid continuously — unlike humans, who only produce acid in response to food. This means an empty stomach is an acidic stomach. In the wild, horses graze for up to 16 hours a day, keeping the stomach full and buffered. Modern management creates a very different picture.

Key risk factors include:

Limited forage access — stabling, restricted grazing, or long gaps between meals

High-concentrate diets — grain and sugar-rich feeds increase volatile fatty acid production, which damages the squamous mucosa

Intense exercise — physical exertion causes the stomach to compress, splashing acid onto the unprotected upper mucosa

Frequent transport — travel is a significant physiological and psychological stressor

Competition and routine changes — disruption to feeding schedules and environment elevates cortisol levels, which impairs the stomach's protective lining

NSAID use — anti-inflammatory medications (e.g., bute/phenylbutazone) reduce the protective prostaglandins in the stomach wall

Diagnosis: When to Call Your Vet

The only definitive diagnosis for gastric ulcers is gastroscopy — a camera examination of the stomach under mild sedation. If your horse shows multiple signs from the list above, particularly girthiness, recurrent colic, and behaviour changes together, a gastroscopic examination is strongly recommended.

Do not attempt to self-diagnose or self-treat without veterinary guidance. Active, severe ulcers typically require pharmacological treatment (omeprazole is the current gold standard recommended by ECEIM) before or alongside any nutritional support.

Prevention — How Nutrition and Supplementation Can Help

Once ulcers are treated, or to prevent them from developing in the first place, management and nutritional strategies are highly effective.

Management fundamentals:

Ensure constant access to forage (hay or pasture) — roughage buffers stomach acid physically

Avoid exercising on an empty stomach — feed hay 30–60 minutes before work

Reduce concentrate meals and split daily rations into at least 3 feeds

Minimise unnecessary stressors — routine, turnout, and social contact matter

Nutritional supplementation:

Several ingredients have been shown to support gastric mucosal health and are recognised by ECEIM for their role in managing EGUS:

Pectin and Lecithin — form a protective hydrophobic layer over the squamous mucosa, reducing acid damage. The combination (pectin-lecithin complex) is specifically recommended by ECEIM.

Magnesium — acts as a natural antacid, buffering excess stomach acid

Sodium bicarbonate — another effective acid buffer, commonly used in preventive formulas

Sea buckthorn (Hippophae rhamnoides) — a 2012 clinical study at Louisiana State University found significant reductions in glandular ulcer scores in supplemented horses (read study)

Live yeast (Saccharomyces cerevisiae) — supports microbiome stability and is recognised by ECEIM as a preventive agent

L-Glutamine — an amino acid essential for intestinal mucosal repair and regeneration

Aloe vera and Althaea officinalis — soothing botanicals that support the gastric mucosa

VetGen GastroBalance — Prevention Designed Around the Evidence

VetGen GastroBalance is formulated specifically for horses at risk of gastric issues — performance horses, competition horses, horses in regular transport, and those on high-concentrate diets.

The formula brings together all key ECEIM-recognised ingredients in a single daily supplement:

Pectin + Lecithin — for mucosal protection (the ECEIM-recommended combination)

Magnesium oxide + Sodium bicarbonate — dual acid buffering

Sea buckthorn (1.8g per daily dose) — above-average dosage based on clinical research

L-Glutamin — mucosal repair support

Actisaf (Saccharomyces cerevisiae) — live yeast for microbiome stability

Althaea officinalis, Matricaria recutita, Melissa officinalis — botanical soothing complex

Spirulina + Ascophyllum nodosum — micronutrient and antioxidant support

LCH-certified doping-free — independently tested and verified by the Laboratoire des Courses Hippiques, France's official equine anti-doping laboratory.

Daily dose: 30g | Available as a 30-day supply (900g)

Summary

Gastric ulcers are far more common than most horse owners realise — and the signs can be easy to miss. Girthiness, subtle behaviour changes, poor coat condition, and recurrent mild colic are all worth investigating. With the right management, forage strategy, and targeted supplementation, they are also largely preventable.

If you suspect your horse has ulcers, consult your vet first. If you're looking to protect a healthy horse from developing them, nutritional support with evidence-based ingredients is one of the most effective tools available.

References

ECEIM Consensus Statement — Equine Gastric Ulcer Syndrome in Adult Horses (Sykes et al., 2015). Journal of Veterinary Internal Medicine. https://onlinelibrary.wiley.com/doi/10.1111/jvim.13578

Huff, N.K. et al. (2012). Effect of Sea Buckthorn Berries and Pulp in a Liquid Emulsion on Gastric Ulcer Scores and Gastric Juice pH in Horses. Journal of Veterinary Internal Medicine. https://pubmed.ncbi.nlm.nih.gov/22845737/

Merck Veterinary Manual — Gastric Ulcers in Horses. https://www.merckvetmanual.com/digestive-system/gastrointestinal-ulcers-in-large-animals/gastric-ulcers-in-horses

UC Davis Center for Equine Health — Equine Gastric Ulcer Syndrome. https://ceh.vetmed.ucdavis.edu/health-topics/equine-gastric-ulcer-syndrome

Lensing et al. (2026). Update on diagnosis, nonpharmacological treatment and prevention of EGUS. Equine Veterinary Education. https://beva.onlinelibrary.wiley.com/doi/10.1111/eve.70037

This article is for informational purposes only. Always consult your veterinarian for diagnosis and treatment of gastric conditions in horses.