Horse Gastric Ulcer Syndrome | Animal Welfare Hub

Equine gastric ulcer syndrome (EGUS) affects the majority of performance horses and a significant proportion of leisure horses — chronic gastric pain is one of the most underdiagnosed welfare problems in equine medicine.

Key Facts

Equine gastric ulcer syndrome affects an estimated 60–90% of racehorses, 40–60% of sport horses, and 11–67% of leisure horses
Horses evolved to graze continuously — their stomachs produce acid constantly, unlike humans whose acid production is meal-triggered
Restricted forage access, high-starch diets, intense exercise, and stress are the primary risk factors
Signs include poor body condition, reduced performance, behavioural changes (girthiness, reluctance to work), teeth grinding, and recurrent colic
Diagnosis requires gastroscopy — direct visualisation of the stomach lining under sedation
Omeprazole (Gastroguard/Ulcergard) is the primary treatment, typically for 28 days with dietary and management changes
Prevention centres on unlimited forage access, reduced concentrate feeding, regular turnout, and minimising transport and competition stress

Welfare Considerations

Gastric ulcers cause chronic, persistent abdominal discomfort — a gnawing pain that affects horses throughout their working and resting lives. The subtlety of the signs means many horses perform their jobs in pain for months or years before diagnosis. The behavioural changes associated with EGUS — girthiness, back soreness, reluctance to canter — are frequently misinterpreted as training problems or naughtiness, leading to increased pressure on already uncomfortable horses. The welfare ideal is prevention through management that respects equine digestive physiology: unlimited forage access is the single most important protective factor and the most consistently neglected in competition horse management.

What You Can Do

Provide unlimited access to forage (hay, haylage, or pasture) for all horses — this is the single most important preventive measure
Reduce high-starch concentrate feeds, particularly before exercise, and feed little and often
Ensure horses have forage available when travelling and at competitions — empty stomachs increase ulcer risk during stress
If your horse shows girthiness, poor performance, or behavioural changes, discuss gastroscopy with your vet
Complete the full omeprazole treatment course and address management factors to prevent recurrence
Support research into EGUS management and prevention at equine veterinary schools
Advocate for EGUS prevention to be included in horse welfare codes of practice and competition horse management standards