May 28, 2021 8 min read

What do we know about Gastric Ulcers in Horses?

Well, according to researcher and Ulcer expert, Dr Ben Sykes, there are two types of Gastric ulcer disease in horses, seen as two distinctively different diseases with different causes, they require different approaches to treatment.

The stomach is divided into two parts:

  1. The upper Squamous part, which is non-glandular, similar to the lining of the oesophagus it does not secrete stomach, acid or digestive enzymes. Ulcers in this area are referred to as Squamous Ulcers.

  2. The lower Glandular section is lined with glandular mucosa and secretes acid continuously regardless of stomach contents. It is more efficient at protecting itself against acid due to the slimy mucosa that lines this part of the stomach. Ulcers in this area are referred to as Glandular Ulcers

Gastic Ulcers In Horses

These two different types of Ulcers are independent of one another, they can occur separately and sometimes concurrently, however one does not necessarily determine the presence of the other.

Squamous Ulcers

The research shows that the Squamous ulcer disease is clearly a disease of management and environment. The prevalence of this disease increases with a high carb, low roughage diet and the risk increases again with frequent exercise of long duration.

  • Carbohydrate content of the diet - The high carb content means that there is a higher rate of starch digestion happening in the stomach which can lower the PH making it more acidic.

  • Roughage content of the diet – Diets low in roughage have a two-pronged effect, firstly there’s not as much saliva being produced as the chewing process is shorter, saliva is high in bicarbonate and buffers acid. And secondly, when the stomach is empty the acid is able to splash from the lower glandular area into the upper less protected squamous area causing lesions.

  • Exercise frequency and duration – this has been associated with the severity of squamous ulcers. In any gait above a walk, the abdominal muscles and contents put pressure onto the stomach literally squeezing the acid from the bottom area into the top squamous area. The more frequently this occurs, as well as the duration, drastically increases the risk of Squamous stomach damage and exposure to acid.

The main signs that a horse could be suffering from Squamous Ulcers include:

  • Depressed appetite, horses can go off both their grain and roughage portions

  • Decrease in body condition

  • Poor performance

Glandular Ulcers

Glandular Ulcers are quite different to Squamous ulcers and form in the lower glandular section of the stomach where acid is present all the time. The research shows that these types of ulcers can occur in a different population of horses and in fact are more common in horses considered at low to zero risk of ulcers. They do not seem to be related to environmental or management factors.

Glandular ulcers tend to be observed in horses who are suffering from stress and have also been found to be more common in Warmblood horses. It’s is unclear why at this stage, it could possibly be due to genetics or behavioural factors.

The main signs that a horse could be suffering from Glandular Ulcers include:

  • Pain behaviours

  • Irritability and a change in attitude to work

  • Personality changes

  • Has been linked to frequent colic episodes


An accurate Diagnosis of Ulcer type and severity is important as this will determine what type of intervention to put in place for treatment, recovery and long-term management.

The only reliable way to diagnose Ulcers and Ulcer location is through the use of a Gastroscopy. It will also give you a baseline for follow up checks and monitoring of treatment.

As we saw in our previous article on Ulcers, diagnosis based on observation of clinical signs is unreliable at best.

A recent study in Polish pleasure horses included over 100 horses in light non-competition work. They split the horses into two groups, one group was displaying typical ulcer symptoms, the other had no symptoms.

The interesting thing about this study is that it clearly demonstrated that the observation of symptoms is not a reliable factor in determining whether or not a horse is likely to have ulcers. This was demonstrated by the fact that 21% of the symptomatic horses did not have ulcers and 63% of non-symptomatic horses actually did have ulcers.

The study clearly showed that the only way to definitively diagnose ulcers is via a complete gastroscopic examination.


The approach to treatment will vary on the location of the Ulcers however in both types of Ulcers the main approach is to lower the acidity of the stomach.

Omeprazole as drug therapy

Omeprazole is the go-to drug therapy and is in a class of medications called proton-pump inhibitors. It works by decreasing the amount of acid made in the stomach.

According to Dr Ben Sykes and current research, considerations for Omeprazole therapy include:

  • Stomach acid needs to be supressed for over 16hrs for healing to take place

  • Squamous Ulcers will need Omeprazole treatment for around 21 days but Glandular Ulcers will need a much longer duration of treatment, between 4-6 weeks depending on the ulcer location

  • 21% of horses with Squamous ulcers do not respond to oral Omeprazole use and a follow up Gastroscope will be needed to determine response to treatment

  • Drug treatment is MUCH more effective if given on an empty stomach – this may seem counter intuitive however the research strongly supports this in the acute treatment phase

  • Omeprazole dose determines the duration of acid suppression not amount of acid suppression.

The downside to Omeprazole, is that horses, like humans on antacid drugs, can have a rebound effect. This means that when they come off the acid suppression drugs the acidity can rebound at a higher rate than before drug therapy.

The duration of this effect will be determined by the duration of treatment. If Omeprazole is only given for a short time then the stomach acid may only rebound for a few days/weeks, however if the horse has been on Omeprazole for months then the horse may suffer from much higher-than-normal amounts of acid for a longer period.

It is therefore important to potentially taper off the omeprazole and at the very least increase preventative measures in the days/weeks after drug therapy. More on this shortly.

Coating Agents and Buffers

There are some other supplement options to help horses recover from and prevent Ulcers. It’s important that you choose manufacturers that produce quality research-based products.

Herbs such as Aloe Vera can be helpful however individual response to these treatments can vary widely between horses and should be used after the initial drug treatment finishes.

A coating agent such as Sucralfate can be used. Sucralfate is a polymer of sucrose with aluminium hydroxide. It forms a protective coating on the mucosal stomach lining, particularly in ulcerated areas. In the presence of acid, it becomes a gel that adheres to epithelial cells and ulcer craters.

A horse’s saliva is high in bicarbonate which makes it a very effective buffer for stomach acid. This is relevant because a horse produces much more saliva chewing on hay as when eating grain. This is due to the horse having to chew longer on the rough forage than on grain. Forage also requires larger jaw sweeps/chews and generally takes more work and time to form into the moist bolus required for easy swallowing, this allows the moist food to be mixed with more saliva which in turn makes it a much more effective buffer.

Recovery, Management and Prevention tips

Lucerne hay is the most effective forage buffer. Along with acting as a buffer, it also forms a protective mat in the stomach and helps to stop acid splashing up onto the squamous region.

The picture below shows the upper and lower sections of the stomach, what happens to Acid when the stomach is empty in contrast with a stomach full of Lucerne hay.

Gastric Ulcers In Horses

The downside is that you don’t want to feed too much Lucerne on a regular basis as its nutritionally very dense. A better choice would be free choice low nutritional quality hay for the majority of the day, then the lucerne in the hour or two before work. Depending on the calorie needs of the horse I would recommend between ½-1 biscuit/day and defiantly time it before exercise. Choose hay over chaff as this will increase chewing time and saliva production.

Exercise as a risk factor

The prevalence of Ulcers goes up with duration and frequency of exercise. The time of day that exercise is performed is also relevant.

Horses eating patterns naturally slow down during the night-time, this means that their stomachs are emptier in the morning. Schedule exercise in the late morning or afternoon so the horse has had a good several hours of eating to fill up the stomach before exercising.

Duration of acid splash during exercise is also important, keep work sessions short and focus on quality not quantity.

Give horses 2-3 rest days per week when recovering from Ulcers.

Avoid concentrate feeds prior to work as they can make the stomach more acidic.

Water intake

Water intake drastically reduces the acidity of the stomach due to dilution, staying well hydrated also ensures adequate saliva production.

Minerals and gut health supplements

Feeding a good mineral balancer is very important for general health but also choose one that’s high in Zinc as this mineral is particularly important for wound healing.

Research has found that Zinc promotes the signalling for Epithelial (stomach lining) repair. Its important for immune function and protects the body from antioxidants and free radicals. Zinc has also been shown in other species to be effective for healing ulcerated glandular gastric mucosa.

Supplements that contain gut support in the form of pre and pro biotics can also increase the health of the gut which builds resilience to disease and helps to form a strong immune defence.

A good choice as far as a Trace mineral and Gut support combo would be our Missy’s Bucket GUT-Plus Supplement. Along with being one of the highest dosed Zinc supplements on the market, it also contains Prebiotics and Probiotics backed by sound research. 

Treatment for Stomach Ulcers in Horses

Stress and other factors

Horses that are stressed have been found to be at higher risk. Particularly for Glandular Ulcers.

Ensure your horse is kept in a social environment. Tolerance to disease is much greater in horses who are not socially isolated, ideally paddocked in a herd, horses need to be able to engage in natural social behaviour like mutual grooming etc.

Also consider the horses general handling and work routine. Does the horse get handled by different people, or ridden by different riders who expect different things from the horse? This could be considered an extreme source of stress for a competition horse.

Travel and living conditions… frequent traveling and changes in living conditions can be stressful for horses, try to provide a steady environment with a good routine and familiar handlers and riders.

Is the horse in Pain? Apart from the pain from the ulcers, other types of pain can cause stress in horses, investigate muscular skeletal pain, hoof pain and saddle induced pain as possible causes of physical and mental stress.

Is stabling a risk factor? Research done in New Zealand on racehorses has shown that keeping horses on pasture is not protective against ulcers.In the study 171 horses were assessed, both thoroughbreds and standardbreds. The prevalence and severity of ulceration did not differ between horses stabled full time, kept at pasture for some of the day or kept at pasture full time, nor did it differ with the quality of the pasture.

If clinical symptoms reoccur then its recommended to scope the horse again to determine if treatment and management is effective or not.


It’s important to be aware of Ulcers in horses, be on the lookout for the risk factors and potential signs, but also be aware that the signs may not be obvious. Ulcers are frequently over-diagnosed based on clinical signs alone.

If you’re concerned, speak to your vet about a Gastroscope and drug therapy as a first step. Adhere to good management practices and support the horse by feeding a top-quality vitamin and mineral mix, gut support and stick to research-based products when it comes to other supportive supplements.

More reading and resources:

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