The causes of gastric ulceration depend on the type of ulcers i.e. squamous or gladular. The factors that contribute to squamous ulceration are better understood than those underlying glandular ulceration, in particular the dietary factors involved in squamous ulceration.

Squamous ulcers occur when the upper part of of the stomach (the squamous region) is exposed to excessive amounts of acid. In a natural environment the horse will graze for up to 16hrs a day, so acidity is reduced by forage passing through the stomach almost constantly, as well as by bicarbonate in the saliva that is produced as the horse chews.

If stabled horses have access to ad-lib hay, haylage or grass, this natural preventative process continues. But if they are fed high-concentrate diets with only limited access to forage, the acidity in the stomach can increase. Prolonged periods without forage intake, whether due to management practices or illness, leads to increased gastric acidity and a risk of sqamous ulcers. Training which includes fast work, especially on an empty stomach, increases the risk of the acid splashing around, resulting in damage the upper part of the stomach.

The causes of glandular ulcers are less well understood, although increased levels of stress and exercise may be involved. 

Research undertaken in the UK on the stomachs of slaughtered horses showed that even feral ponies living on the moors can develop gastric ulcers, although it was unclear whether they were living with them all the time or had developed them during the brief period between round-up and slaughter. The samples were all taken from animals slaughtered in mid-summer, when grazing was at its best and the predicted environmental stress at its lowest.

There are no definitive external signs that a horse is suffering from gastric ulcers, but clues suggesting a performance horse may be suffering include:

• decreased performance
• attitude change (reluctance to work/not wanting to be tacked up)
• poor body condition
• reduced appetite
• low-grade colic

But, all of these problems can have a large number of other causes. Also gastric ulcers may show now outward signs. The only accurate way to find out if ulcers are present and what grade they are, is to use an endoscope to examine the stomach (gastroscopy).

Gastroscopy is performed under sedation and sometimes using a twitch. The gastroscope is a 3 meter long flexible fibre optic camera which is passed up one of the horse’s nostrils, the horse then swallows the gastroscope which is passed down into the stomach. Once inside the stomach, the stomach is inflated with air to allow full examination and the scope is manoeuvred to examine different regions of the stomach.

The procedure is usually well-tolerated by the horse and takes around 20 minutes. Horses are ready to travel home when the sedation has begun to wear off (usually after about 30 minutes).

Please note:

• YOUR HORSE MUST BE STARVED FOR AT LEAST 16 HOURS BEFORE THE APPOINTMENT.
• WATER SHOULD BE WITHHELD FOR APPROXIMATELY 3 HOURS BEFORE THE APPOINTMENT.​
• THE EXAMINATION CANNOT BE FULLY PERFORMED IF THE HORSE HAS NOT BEEN STARVED OR IF THERE IS STILL FOOD PRESENT IN THE STOMACH

For horses inclined to eat their bedding, a muzzle should be placed. Both food and water can be made available to the horse as soon as the effects of the sedation have worn off.

There are rarely any untoward side effects of gastroscopy, although occasionally a horse may show mild colic symptoms associated with distension of the stomach by air but this usually resolves one the air is withdrawn at the completion of the procedure.

Occasionally the gastroscopy procedure may result in a small nose bleed. This is perfectly harmless and will stop within a relatively short time.

Squamous gastric ulcers are usually treated with a paste given by mouth which contains an equine-specific form of omeprazole, a medication that reduces acid production in the stomach. Other medicines are now being used in some cases. How long the horse requires treatment and the most appropriate medicine to use will depend on a range of other factors that should be discussed with your vet

Most cases of squamous ulceration respond well to treatment within 28 days. After 28 days gastroscopy is often repeated to check how the healing is progressing. If all is well then changes in dietary management, and in some cases, contiuned treatment will continue in order to reduce the risk of recurrence of the ulcers. A reduced dose of omeprazole (1/4 dose) may be used particularly during periods of stress. Feed suppliments (such as those containing aluminium hydroxide, magnesium hydroxide and calcium carbonate - think 'Rennie for your horse) are also used in some cases, but need to be given frequently. 

Cases of glandular ulceration often improve within 28 days but commonly take longer to heal than squamous ulcers. Glandular ulcers generally require different treatment from squamous ulcers. Treatments include sulcralfate (a mucosal protectant) and misoprostal (a prostaglandin analogue). Although these medicines are commonly used they are not licensed for use in horses and their use will be discussed by your vet.

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Do be of weary of sourcing potentially cheaper ulcer medications on-line.

During October & November 2024, a huge number of medications destined for the UK were seized by the Veterinary Medicines Directorate (VMD) working alongside the Government Border Force agency. These products were medications aimed at treating equine ulcers and were brought into the country illegally.

You can read an article by the British Equine Verterinary Association (BEVA) on the seizure HERE.

Any horse that has been diagnosed as having gastric ulcers, alongside horses that are high-risk of developing them, needs their management reviewed in order to reduce the likelihood of the ulcers taking hold.

The following steps are recommended:

• Allow access to high-quality forage, predominantly during the day (7am to 11pm), at a minimum daily rate of 1.5kg/100kg body weight (BWT). This should ideally be given continuously or at no more than 6hr intervals
• Create multiple forage sources in the stable to improve eating consistency and allow foraging activity
• Either hay (dry, soaked or steamed) or haylage can be used as the main forage source — there’s no difference between them in relation to ulceration
• Feed no more than 0.25kg/100kgBWT of straw. This should not be the only forage source
• Provide continuous access to fresh, clean water 24hrs a day
• Split the concentrate ration into three rather than two meals per day
• Opt for grains such as barley and oats instead of sweet feeds
• Add chaff to all meals
• Completely pelleted diets generate more stomach acid than the same diet formulated as a coarse mix
• Buy high-quality feed, but bear in mind that there is no scientific evidence to support the use of specific “gastric healthy” commercial diets, nor of one manufacturer’s feed being better than another’s
• Add a little corn oil or rapeseed oil (50-100ml per day) to help reduce the amount of stomach acid produced
• Consider using fermented probiotics and the yeast Saccharomyces cervasii, which may increase the digestibility of the horse’s diet, so improving large intestinal function
• Feed chaff before exercise — 2 litres chaff given within 30mins of exercise may trap acid and limit ulceration, and improve gastric blood supply. Use a 2-litre plastic drink bottle with the top cut off as a measure
• Remember turn out at grass is beneficial for the majority of horses

If you have any questions about any aspect of gastric  ulcers, please call BELL EQUINE on 01622 813700 and speak to one of our vets.