11/10/2025
About Equine Stomach Ulcers â Causes, Whatâs Going on Inside, Treatments & Prevention
Ulcers and chronic stomach inflammation are quite common in modern horses. Top performance horses are just as affected as those used for pleasure or trail riding. In most cases, the culprits are incorrect feeding and/or stress.
But where do ulcers come from and what can be done to prevent them?
Statistics show that about 90% of all racehorses and approximately 60% of other horsesâwhether foals, trail-riding, or competition horsesâsuffer from stomach ulcers.
The stomach is only a small part of the digestive tract but plays a crucial role: this is where stomach acid is added to prepare the feed for further digestion in the intestines. This function has not changed in the evolution of the domesticated horse compared to its wild ancestors.
The equine stomach consists of two parts, lined with two different types of tissueâone glandular and one non-glandular. Most ulcers occur at the junction of these two parts. The relatively small stomach is designed to digest small amounts of feed continuously, 24/7. The glands produce acid constantly to help break down foodâan ideal system for a wild animal grazing up to 18 hours a day with little stress.
However, domesticated horses face a very different life. Instead of constant access to fibrous grass, theyâre often given high-energy grain meals. Instead of the security of a herd, many horses are stabled alone or in small paddocks, with restricted movement. The horse in the next stall may not be a companion they would have chosen, and travel for competitions or trail rides means more separation from familiar environments.
All of these are stress factors and stress increases stomach acid production. The good news is that horses are generally very good at adapting to new situations. The bad news? Their stomachs are not. Thatâs why we must manage the factors that affect their digestive healthâor risk ulcers developing.
Chewing = Protection
Thereâs an old saying: âWell chewed is half digested.â Bullseye!
A horse produces 5â10 litres of gastric juice per 100 kg of body weight every 24 hours. That means a 600 kg horse can produce 30â60 litres of stomach acid per day! Most of this is hydrochloric acid, which is highly corrosive.
Saliva, produced during chewing, contains bicarbonate, which acts as a buffer to neutralise acid. The more a horse chews, the more saliva it producesâand the more protection it has. No chewing means little saliva, and the acid starts damaging the stomach lining.
Thatâs why roughage should always be available. Feed passage through the stomach takes 1â5 hours, so a horse without access to hay or grass for more than 4 hours is left with an unprotected stomach lining.
Unlike humans or dogs, horses produce stomach acid continuouslyâwhether they are eating or not. After the feed is pre-digested in the non-glandular part of the stomach, it enters the glandular part, where acid kills microbes and prepares it for further digestion.
Letâs look at chewing statistics:
* Eating 1 kg of hard feed: ~10 minutes, ~700 chewing motions, ~900 ml saliva
* Eating 1 kg of hay: ~40 minutes, ~2,800 chewing motions, ~6.3 litres of saliva
Thatâs a huge difference! Hard feed drastically reduces acid-buffering saliva. High levels of starch and molasses further increase acid production.
Feeding Matters
Historically, a meal for a heavy horse might have included 400 g corn/barley + 500 g oats per 100 kg body weight. Modern recommendations have reduced that to 400 g oats and 250 g corn/barley.
For a 500 kg horse, the maximum per meal would be:
2 kg oats
1.25 kg corn/barley
Todayâs performance horses are often fed far more than thatâespecially racehorses, who typically receive a small pre-training meal, a moderate lunch, and a large evening feed. This feeding pattern explains the high incidence of ulcers in this group.
Not Just Feeding â Stress Matters Too
As discussed, stress increases acid production, reduces blood circulation to the stomach lining, and impairs digestion. And itâs not just competition stress. Pleasure and trail horses can be just as affectedâoften due to their lifestyle.
Watch your horse during dinner: does it eat calmly with its head down, or does it sn**ch quick bites and constantly scan its surroundings? Anxious horses are more likely to develop ulcers because they donât chew properly, produce less saliva, and fail to buffer the acid.
(On a personal note: to our knowledge, none of our customersâ horses that were previously prone to ulcers redeveloped them after being supplemented with NervoMag đ)*
Stress can come from:
Living with incompatible horses
Ill-fitting tack
Inconsistent routines
Daily exposure to new locations and stimuli
Horses are creatures of habit. Establishing consistent routinesâwhether in feeding or trainingâcan significantly reduce stress. A structured cross-training pattern (e.g. lunge, dressage, jump, trail, repeat) gives horses a sense of predictability and reduces anxiety.
The same applies to feeding. Horses anticipate meals. If the feed is late, acid production has already ramped upâwithout the buffer of saliva, the stomach lining suffers.
âFlight or Fight?â
For horses, the answer is almost always âflight.â Their autonomic nervous system drives organ function independently of conscious thought. When stressed, blood flow is redirected from the digestive system to the muscles to aid escape.
In nature, this is short-livedâthe horse either escapes or doesn't. In modern life, ongoing stress keeps the digestive system under pressure, causing damage. Once stress subsides, acid production increases again, which can compound the damage.
Training Can Also Be a Factor
The equine stomach is designed for continuous movement and grazing, not long periods of intense exercise. During prolonged trotting or cantering, abdominal muscles compress the stomach, forcing acid upward into the unprotected non-glandular region.
The risk of damage depends on:
How much feed is in the stomach
The buffering quality of the feed
Duration and intensity of exercise
Whether breaks and walking are included
Conclusion: Training and Feeding Tips
Ensure regular, well-planned, and stress-free training sessions
Include frequent breaks with walking
Avoid long periods without feedâespecially overnight
Always feed hay before hard feed
Avoid feeds high in starch or molasses
Donât exceed safe hard feed limits
Other Causes of Equine Stomach Ulcers
Besides stress and feeding, consider:
Physical conditions:
Dental issues (have teeth checked annually by an equine dentist)
Windsucking
Feed thatâs too hot or frozen
Mechanical damage (e.g. woody hay)
Uncooked barley
Stomach parasites
Chemical conditions:
Pesticides or fertilizers
Spoiled silage
Long-term use of certain medications (e.g. NSAIDs)
Common Symptoms (Often Misinterpreted)
Weight loss
Loss of appetite
Pausing during eating
Poor digestion of stalky hay
Light colic with no clear cause
Dull coat or coat colour change
Reduced performance
Yawning or âemptyâ chewing
Teeth grinding
Increased windsucking
Depression
Social withdrawal or sudden aggression
Girthiness
Discomfort when being mounted
Difficulty walking downhill or lying down
Sudden increase or decrease in water intake
Licking metal objects
Runny manure (often linked to gut inflammation as well)
Note: These signs can also indicate other conditions, so veterinary consultation is essential.
Gastroscopy â Not Always Definitive
Gastroscopy is currently the only reliable method to diagnose ulcers. If ulcers are found, they are definitely thereâbut the absence of ulcers on a scope does not mean they wonât appear soon after.
Gastroscopy is expensive and uncomfortable for the horse, so the best approach is prevention.
Treatment of Equine Stomach Ulcers
Omeprazole, used successfully in human medicine, blocks acid production. While effective, its long-term effects in horses are not fully understood. For example, foals treated with omeprazole may be more prone to gut or lung infections.
Other medications may reduce or neutralise acid or help protect the stomach lining.
Natural approaches include:
Always feeding roughage before hard feed
Adding banana peels or slippery elm to the feed
Summary: The Pillars of a Good Feeding Protocol
Avoid long periods without feed (never more than 4 hours)
Ensure hay is available overnight
Always feed hay before hard feed
Avoid high-starch and molasses-rich feeds
Respect maximum safe levels of hard feed
On a Personal Note:
At SonoVet, we always aim for prevention first. If an issue arises, we work to address the root causeânot just mask symptoms with medication.
Most ulcers are stress-related, not just diet-related. A horse constantly scanning its environment doesnât chew properly
www.sonovettherapy.com.au
Photo by BananaStock
