Understanding Ulcers in Horses & Insights on how to support your Horse

Understanding Ulcers in Horses & Insights on how to support your Horse

Understanding Ulcers in Horses & Insights on how to support your Horse

Stomach ulcers (also called gastric ulcers) are one of the biggest challenges you can face as a horse owner. Unfortunately, ulcers in horses are extremely common, occurring in between 50-90% of our horses.

Ulcer treatment is expensive, and some horses can’t seem to escape the vicious circle of ulcers returning once treatment finishes.

It's not easy to tell if your horse has ulcers

Most horses with gastric ulcer show very few, if any, clinical signs. Girthiness in horses is much more likely to be associated with back pain or hindgut ulcers and gut inflammation than with stomach ulcers.

Clinical signs which are commonly associated with gastric ulcers are: mild colic episodes especially associated with mealtime, dullness, attitude changes, reluctance to train, poor body condition, poor hair coat, weight loss.

It is important to get an accurate diagnosis when dealing with suspected gastric ulcers by performing a gastroscopy (stomach scope). Without a definitive diagnosis, owners are subjecting their horses to unnecessary medication and potentially prolonging further suffering if gastric ulceration is not the cause of the symptoms. 

Scoping for ulcers also enables you to make decisions about treatment - your vet can see which part of the stomach is ulcerated, which will likely influence what treatment and management changes they recommend. It’s also important to conduct follow up scopes so you can monitor how effective the medication is, and when it’s time to safely stop it.

Top tip: Always ask your vet what part of the stomach the ulcers were found in, and what treatment plan they recommend. 

What exactly are Gastric Ulcers in horses?

Gastric ulcers refers to the damage (lesions) caused to the inner lining (mucosa) of the horse's stomach. There are two different types of gastric ulcers – ‘squamous’ and ‘glandular’ – and the distinction relates to where they occur in the stomach. It’s important to differentiate between the type of gastric ulcer your horse suffers from, as they have different risk factors, causes and implications for treatment.

Squamous ulcers

Where are squamous ulcers? Squamous ulcers occur in the upper part of the stomach, where the delicate tissue – like our skin – has a limited ability to protect itself from gastric acid (stomach acid).

What are the signs of squamous ulcers? Likened to heart burn, the most common signs of squamous ulcers include difficulty maintaining weight (generally due to reduced feed intake) and changes in behaviour.

What causes squamous ulcers? The most common causes of squamous ulcers are diet and exercise related, including inadequate forage intake, large grain-based meals, and high intensity exercise. Working your horse on an empty stomach may also contribute to squamous ulcers. This happens because if the stomach is empty, stomach acid can splash up onto the delicate squamous region and cause damage to the stomach wall.

The risk factors for squamous ulcers are things we can control and manage with appropriate nutrition. 

Glandular ulcers

Where are glandular ulcers? Glandular ulcers occur in the lower part of the stomach. As the name suggests this area contains the many glands which secrete things like gastric acid and mucus in the stomach. 

What are the signs of glandular ulcers? Glandular ulcers are more commonly associated with signs of pain or discomfort such as irritability, reluctance to work, changes in personality and colic. Not all horses show these classic signs, and some show no signs at all. 

What causes glandular ulcers?

The causes of glandular ulcers seem to be more complex, and we don’t know all the risk factors yet. Based on current knowledge, risk factors include breed – with warmblood horses more commonly represented – and exercise, if horses are exercised more than 5 days per week. 

Stress is also thought to play an important role, so management to reduce stress is vital, and remembering that the causes of stress can vary between horses. Research suggests that the changes in environment and management associated with domestication may be increasing the risk of glandular ulcers.

Why do horses get ulcers?

Times spent without feed (travel, long rides, confinement without forage/hay) can lead to the horse having an empty stomach, which means acid can splash up onto the delicate squamous region and cause damage to the stomach wall.

There are four major risk factors for developing ulcers:

  • exercising on an empty stomach,
  • high grain diets,
  • stall confinement,
  • and transport stress.

"It is often impossible to reduce training and transport. I don’t feel it is the training and transport which causes ulcers, it is the stress associated with such situations.  Take the time to educate and acclimatize your horses to the experiences they will encounter in their lives.  Introduce them to training, transport, and competition slowly and incrementally so that these experiences never become stressful for the horse." - Dr Erin Roddy

How to help your horse with ulcers

Dietary and housing management are the most important factors to prevent the occurrence or reoccurrence of gastric ulcers.

Horses should be fed on a free choice basis aka round the clock access to pasture or hay if pasture is unavailable. Forage and saliva are the very best antacids (and the cheapest)

What would your horse want you to know?

Too often we assume our horses are like us. And they are in many ways. They need connection, they love their friends and they get scared of stuff just like we do. But, they are also very different in so many ways too!

One major difference is their stomach. Their stomach is designed to never be empty - and they can very happily run with food in their stomach; in fact running with a full stomach is a reason the species has survived predation.

Because horses evolved to eat for most of the day and night, their stomach produces acid constantly, which helps explain why horses are so susceptible to ulcers if they are left without food for extended periods.

"A horse’s stomach is incredibly small in comparison to other species as they are designed to eat small amounts of food continuously. And when the stomach is empty, especially before exercise, acid splashes up on to the sensitive part of the stomach damaging the lining and causing ulcers." - Dr  Erin Roddy

Top tip: When you are saddling up, give your horse some hay or lucerne to eat, especially if he has been off feed for an hour or more.

An Equine Veterinarian explains why Poseidon supplements are relevant to ulcers in horses

"The main contributing factors to gastric ulcer formation in horses is too much acid in the stomach, and stress.  Both Digestive EQ and Stress Paste are designed to coat and alkalinize (make less acidic) the stomach and entire GI tract protecting the stomach and hindgut from the acidic contents of the GI tract.

An unbalanced microbiome is one of the biggest reasons horses don’t eat well, and don’t process the food that they do eat well.

Digestive EQ, Digestive RP and Stress Paste are specifically designed to help the horses generate a healthy and diverse microbiome and to continue to support horses as they transition into this state. The more diverse and balanced the microbiome, the more the horses want to eat (especially forage and fiber) and the better they process these foods. This in turn helps owners wean horses off of the starchy and sugary feed components which predispose horses towards ulcers such as high grain and wheat biproduct based diets." - Dr Erin Roddy

    Supplements to support the horse's gastrointestinal tract 

    Digestive EQ or Digestive RP and Stress Paste all act to support and protect the GI tract and nervous system through the stressors of training and travelling. A gastrointestinal tract that is supported during both the daily stressors, and the more extreme stresses (such as travel, competition, illness, and weather extremes), is more likely to be resilient and functional - and much less likely to develop ulceration.  

    Digestive EQ may help horses who have been on ulcer medication for a long time

    Most ulcer medications prescribed by veterinarians aim to restrict hydrochloric acid production (known as proton pump inhibitors) in the horse's stomach. A reduction of hydrochloric acid secretion allows the stomach environment to somewhat neutralise and allow ulcers to heal.

    These medications only target ulcers within the stomach, therefore if you are not seeing any improvement in your horse’s symptoms which may include girthiness, loose manure, poor performance, dull coat, weight loss and colic, your horse may also have further issues in their hindgut which remain unresolved.

    Digestive EQ aims to support all levels of digestive health from the foregut to the hindgut - and although it does not treat or prevent gastric or colonic ulcerations, it may help your horse to maintain gastrointestinal health by reducing insult of gastric fluid on a healing or recently healed gut, and by providing the nutrients needed to repair the gut wall, and produce mucous for natural protection.

    Many of our customers report that they have successfully weaned their horses off long-term use of gastric ulcer treatments and scopes have remained clear since starting them on Digestive EQ.

    Remember to always seek veterinary advice when concerned about your horse’s health.

    Why is Lucerne hay a good choice to feed before riding ?

    Lucerne hay has been shown to be beneficial for horses with, or who are prone to, gastric ulcers. In addition to the buffering effect of saliva produced from chewing hay, lucerne hay is thought to provide even more buffering due to its high protein and calcium content, compared with grass hay.

    Top tip: Even just ¼ biscuit of lucerne hay prior to exercise can make a radical difference in the prevention of gastric ulcers.

    Lucerne hay is a very cheap and effective method of alkalinizing the stomach in horses.  Lucerne hay has a good protein and caloric content, is less heating than starch or grain, and contains much less sugar than many grass hays. Not only does it alkalinize and protect the stomach, because it is a long-stemmed forage it causes the horse to produce much more saliva which is also the horse’s best way of protecting the stomach from acid.  Further, the lucerne hay stays in the stomach much longer than a starch or sugar meal which means the stomach is protected for a much longer period of time.

    It is not recommended that lucerne hay is the only type of forage in the diet, as it supplies large amounts of protein and calcium. Generally, 2.5-4kg lucerne hay per day for a 500kg horse is a good amount.

    When should I use a Veterinarian Approved Gastric Ulcer Treatment?

    If you suspect your horse has gastric ulcers, call your veterinarian.

    They should be able to properly diagnose stomach ulcers via a gastroscope and determine if your horse requires treatment with a prescription medication. Digestive EQ does not treat or prevent gastric or colonic ulcerations, but it may help to maintain gastrointestinal health by reducing insult of gastric fluid on a healing or recently healed gut, provide the nutrients the gut itself needs to repair the gut wall and produce mucous so it can protect itself naturally. Many of our customers are reporting that they have successfully weaned their horses off long-term use of gastric ulcer treatments since starting them on Digestive EQ and scopes have remained clear. 

    "It is very important to use omeprazole correctly if it is to be effective.  Oral omeprazole must be given to the horse on an empty stomach 30-60 minutes prior to feeding. If the omeprazole is not dosed in this way it will not be effective at treating ulcers or preventing ulcers." - Dr Erin Roddy

    Is your horse constantly on ulcer treatment?

    A recent study in mice, published by ‘Nature’, has shown that omeprazole, the drug of choice for treating gastric ulcers in horses, may be leading to liver disease. The study (Llorente et al 2017) has found that suppressing gastric acid is allowing overgrowth of intestinal Enterococcus. In these mice, the Enterococcus bacteria were able to translocate to the liver, and there they promoted liver injury and progression of chronic liver disease.

    If your horse has ulcers then you must treat them.

    And omeprazole is the drug of choice. BUT, using omeprazole long-term as a form of ulcer prevention may not be wise. The horse’s stomach secretes acid for a reason. And like in ecology, when you take out one critical piece of any living puzzle, other issues are likely to pop up.

    Did you know that effectiveness of Omeprazole as an ulcer treatment declines after 28 days?

    At this stage, we don’t know what happens to a horse’s gut bacteria when they are placed on long term ‘preventative’ doses of omeprazole. It’s by far better to use good feeding management; keeping intervals between feeding as short as possible, feeding lots of forage, feeding at least some lucerne (alfalfa) and ALWAYS making sure a horse’s stomach is full before he is exercised, are the best preventions!

    Are there downsides to treating gastric ulcers with medication? 

    In a word, yes... Unfortunately, as we learn more about gastric ulcers and medication like Omeprazole, we are learning that there are negative side effects and safety concerns, especially with long term use (more than 60 days). 

    NB: The information below is referenced in more detail in this paper.

    Potential increased fracture risk

    In humans, Omeprazole treatment has been associated with an increased risk of fractures. Similar concerns have been raised for horses. The exact cause/s are unknown however it is suggested that the increased secretion of gastrin (a hormone which stimulates acid secretion and regulates glandular mucosal growth) and the decreased digestion and/or absorption of minerals (such as calcium and magnesium) in horses on Omeprazole treatment, lead to decreased bone mineral density.

    Decreased effectiveness with time

    Supported by studies in other species, in horses there was a 50% decrease in bioavailability (absorption and effectiveness) of oral Omeprazole after 28 days of treatment (4mg/kg BW). 

    In two separate studies, 16-20% of horses on a 28 day ‘preventative’ dose (1mg/kg BW & 2mg/kg BW) of Omeprazole, after an initial 28 day ‘treatment’ dose (4mg/kg BW), experienced development or worsening of squamous ulcers.

    The number of horses which responded to Omeprazole treatment (4mg/kg BW) halved between 60 and 90 days.  

    Hypersecretion (the acid rebound effect)

    Acid secretion is regulated by stomach pH – when the pH is above the optimal range, the horse’s body wants to secrete more acid to bring the stomach pH back down (so it’s acidic). However, Omeprazole suppresses acid secretion (to allow ulcers to heal) and pH is increased. But when the treatment stops, a negative feedback loop occurs which causes significantly increased acid production.

    Preliminary studies have shown development of squamous ulcers less than 76 hours after the last dose of Omeprazole (Sykes, B., Unpublished).

    Dangers with concurrent administration of pain medication like Bute

    Horses treated with a combination of phenylbutazone (Bute) in combination with Omeprazole had more intestinal complications, many of them severe, some resulting in death or horses having to be euthanised.

    Disruption of the gut microbiome

    In foals, Omeprazole treatment was associated with diarrhoea. Due to decreased acidity within the stomach, the potential for pathogenic bacteria to survive and disrupt hindgut microbiota may be increased. Further research in this area is needed. 


    This does not mean that you shouldn’t use medication like Omeprazole to treat your horse for gastric ulcers, but it does show just how important it is monitor for healing with follow up scoping, and to reassess the medication plan with your vet if treatment isn’t working after 28 days.

    It also shows us how vital it is to make dietary and management changes – to reduce the risk factors for squamous and glandular ulcers long term – so you can rely less heavily on medication.

    Top tip: It’s important to be aware of hypersecretion (the acid rebound effect) and to consider using a supplement such as Digestive EQ or Stress Paste during the use of medication, to support the healing and integrity of the stomach tissue.

    Watch: So you think your horse has ulcers; what next? 


    Helpful research links