Horses constantly produce hydrochloric acid, but only produce saliva containing buffering bicarbonate of soda while chewing. Therefor, insufficient feed intake, particularly of fibre that requires more chewing than concentrate feeds, may result in ulcers.

* Stress as a result of training and competition, transportation, stable confinement, changes in the environment e.g. change of home or loss of a companion, chronic disease and boredom.
* A high concentrate diet with low-roughage intake.

The management of performance horses often entails stabling for long periods with discreet meals of concentrates, which typically have a high sugar/soluble carbohydrate content. When digested this results in increased levels of acid in the stomach. This together with the intervals between feeds both at home or while travelling or at competitions increases the acidity in the stomach, which does not have the buffering effect of saliva that the constantly grazing animal produces.

* Withholding feed during competitions (see above).
* Continuous acid secretions by the stomach and the lack of buffering of the acid by grass and/or hay (see above).
* Performance e.g. working at speed: Intense exercise increases acid production in the horse's stomach and exercise reduces blood flow to the stomach.

Another performance related cause suggested by Dr. A. M. Merritt, a researcher in equine gastrointestinal problems, is that the high incidence of gastric mucosal ulcers in horses in training, is a mechanical phenomenon caused by an increased exposure of that region of the stomach to acidic gastric contents during exercise. The theory is that the increase in intra-abdominal pressure during exercise pushes gastric contents up into the squamous-lined proximal region of the stomach exposing the mucosa to acid.

The horse does not fill its stomach, and under normal conditions spends most of the day standing or walking about grazing, so this region of the stomach would not be exposed to the acidic content.

* Ulcers caused by toxicity from non-steroidal anti-inflammatory drugs such as Bute™ and Banamine™: It is common practice to give racehorses frequent doses of NSAIDs both for injury and prophylactically. NSAIDs block the release of prostaglandin, which protects the glandular lining of the stomach from the hydrochloric acid and pepsin, which it secretes.

Most frequently cited is poor performance.

Show jumpers exhibit a change in jumping style e.g. hitting jumps, twisting or jumping left or right over a fence.

Dressage horses were found to resist work and difficult to train.

Other signs include colic, inappetance, and loss of weight, behavioural abnormalities, and apparent back pain.

Foals may exhibit tooth grinding, excessive salivation, a potbelly appearance (worms may be another cause), interrupted nursing, lying on the back, rough coat, and poor growth rate.

Usually the horse is referred to the vet on physical signs and the diagnosis is confirmed by gastric endoscopy.

The treatment of stomach ulcers involves a combination of changes of management, the most important being the feed regime. A reduction of stress and possibly medical therapy may also be advised.

Turnout in grass pasture together with altering the feeding regime is the fastest method to allow the ulcers to heal. If concentrates are to be fed, they should be fed in small amounts at frequent intervals (4/day) with as little grain concentrates that produce acid as possible. Steam extruded feeds and sugar beet shreds (an intermediate feed), may be fed which increases chewing time and saliva production. However high fibre content feeds are the most appropriate feedstuffs with at least 1% of bodyweight or 50-70% of the total feed intake as hay or forage being offered.

Horses chew most efficiently with the head lowered and the throat extended, and therefor feed bins and hay placed near or at ground level are most effective.

Antacids (aluminium and magnesium hydroxide) reduce the acidity of the stomach for a short period but must be frequently administered to be effective.

Antacids are of benefit in alleviating the clinical signs of poor appetite and mild colic, but they are relatively ineffective in healing gastric ulcers.

Histamine-receptor antagonists: Cimetidine (Tagamet) and ranitidine (Xantac) are commonly used in the horse and are considered effective in the prevention and treatment of ulcers. They reduce gastric acid production and induced acid production by competitively inhibiting histamine at the H2 receptors of the parietal cells.

Omeprazole (Gastroguard, Pepsid) is the most potent anti-ulcer medication currently available. As a proton pump inhibitor, it inhibits gastric acid secretion by interfering with hydrogen ions in the final stage of acid secretion.

Sucralfate (Carafate) After ingestion, sucralfate reacts with hydrochloric acid in the stomach to form a paste-like complex that binds to the pertinacious exudates that are generally found at ulcer sites. This insoluble complex forms a barrier at the site and prevents the ulcer from further damage caused by pepsin, acid and bile.

Without drug administration, a 4-month period at pasture will usually resolve ulcers.

Herbs that have effectively been used in the treatment of ulcers in horses include; Comfrey leaf, Marshmallow Root, Liquorice, Meadowsweet and Slippery Elm. These all have mucilaginous properties, which provide a mucous protective layer in the stomach.

Aloe Vera and algae and kelp also share these properties.

Manage horses in a species appropriate way i.e. maximum turnout/access to pasture and grazing. If stabled for periods, multiple small concentrate feeds and at least the minimum suggested forage or fibre should be fed.

Reduce stress by ensuring that horses have companions or buddies. Consider carefully before selling on or changing the horse's home. Provide comfortable, species appropriate stables, shelters and travelling arrangements.

Avoid use of anti-inflammatories e.g. Bute.

Ulcers may heal if horses are turned out to pasture for an extended period of time, but they usually don't heal in horses that continue in training, and will re-occur if changes to the management of the horse are not made.