By Vet Hamish Leslie
Has your horse's behaviour recently changed? Have they become ‘girthy’ and irritable, or shown a reduction in performance? Gastric ulcers could be the problem. Equine Gastric Ulcer Syndrome (EGUS) is a common health problem affecting horses of all ages and disciplines. Understanding ulcers can make a huge difference to your horse’s comfort and performance.
A gastric ulcer is an erosion of the stomach lining, causing a painful sore. The horse’s stomach is divided into two sections separated by the margo plicatus, and disease appears differently in each. The non-glandular (squamous) upper section is unprotected and vulnerable to stomach acid. The glandular lower section produces acid and mucus to aid digestion and is normally protected, but ulcers can develop in either section in horses with EGUS.
Horses continuously produce stomach acid, even when they are not eating. Naturally, a horse grazes for up to 18 hours a day, providing a steady flow of forage. Chewing produces saliva, which helps buffer stomach acid and maintain balance.
Modern management often disrupts this balance. Long periods without forage, reduced chewing, high-grain diets, stabling, and intense or frequent exercise all increase risk. Stress from changes in routine, transport, or competition is also a known factor, particularly for glandular ulcers. Exercise itself can worsen squamous ulcers, as abdominal movement causes acid to splash onto the unprotected upper stomach.
Signs vary greatly from horse to horse. Common signs include loss of appetite or picky eating, weight loss, a dull coat, resistance to being touched around the girth, changes in behaviour or performance, tooth grinding, yawning or stretching after meals, and mild recurring colic or discomfort after eating. Some horses show several clear signs, while others may be subtle, with only a drop in performance to indicate a problem.
The only way to definitively diagnose ulcers is through gastroscopy. This quick procedure, performed under standing sedation, involves passing an endoscopic camera up the nose and into the stomach. Horses must be starved for around 12 hours beforehand to allow the stomach to empty. The camera allows the stomach lining to be examined to see if ulcers are present and how severe they are. Paragon Equine now offers this service on yard, meaning your horse does not have to travel.
Gastric ulcers are very treatable. The main treatment is a drug to reduce stomach acid, allowing the lining time to heal. The most common drug used is omeprazole, which blocks acid secretion. Depending on the type and severity of ulcers, treatment typically lasts 4–6 weeks. For glandular ulcers, sucralfate can form a protective barrier while healing takes place. A good-quality gastric supplement can also help maintain stomach health.
Once a horse has had ulcers, they are more susceptible to recurrence if appropriate changes are not made. Maximising turnout and ensuring continuous access to forage when stabled allows horses to perform their natural behaviour of eating and moving throughout the day, keeping the stomach working and saliva buffering the acid. Feeding a handful of chaff, particularly one high in calcium such as alfalfa, before exercise can form a protective layer over stomach acid and reduce splash ulcers. Minimising high-starch and high-sugar concentrate feeds is also beneficial, as these diets ferment quickly and create a more acidic environment.
For horses previously treated for gastric ulcers, low-dose preventative omeprazole may be appropriate during periods of high stress, such as travelling, competing, or changing yards, but always discuss this with your vet.
Horses now lead very different lives from their wild ancestors, but understanding their digestive needs, practising good management, reducing stress, and feeding appropriate diets can go a long way toward keeping your horse’s stomach healthy.