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Caring for horses with stomach ulcers

Do you own or know someone who cares for a horse suffering from stomach ulcers? Caring for a horse with a stomach ulcer brings many challenges and managing them encompasses a range of considerations. Treating them is definitely not a ‘one size fits all’ approach but rather a multi-factorial one. Prevention is always better than cure and this article will discuss how to care for horses with stomach ulcers and the challenges often faced along the way.  

What are stomach ulcers and what causes them? 

Stomach ulcers in horses are usually part of something more complex, often referred to as equine gastric ulcer syndrome (EGUS). EGUS is a nasty condition where the stomach lining contains painful ulcerative and erosive lesions. A horse’s stomach naturally secretes acid to aid the digestion of food, even if their stomach is empty. This acid is then neutralised and buffered by saliva swallowed when your horse eats. When there is a disruption or change to the normal stomach acid composition it can lead to ulcer formation. 

EGUS can be split into two categories: equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD). To keep it simple, the major difference between these categories is the location of the ulcers within the stomach, either in the squamous part or the glandular part.  

The prevalence of gastric ulcers in racehorses has been reported in 60-90%, with actively working racehorses being higher risk (Stefanyk and Slivinska, 2018). EGUS doesn’t only occur in adult horses, but in young foals too! This leads us onto discuss the risk factors of EGUS and what actually causes them. 

When we think about the underlying causes of EGUS, we need to think about husbandry, feeding, stress factors, medications, training level, and transport as these can all be triggers for stomach ulcer development. Of particular importance is leaving a horse without any food for prolonged times, as the horse is a natural “trickle feeder”, but there are many other factors. Unfortunately, EGUS is a complicated condition with many causative factors, and each affected individual may be experiencing more than one cause. Horses experience greater levels of stress at times of sudden changes in routine, and therefore we see more cases of EGUS at this time of the year as the more intense winter months are upon us! 

What are the clinical signs?  

There can be variable non-specific clinical signs in a horse with stomach ulcers, with some being more common than others. The most common clinical signs include the following (this list is not exhaustive): 

  • Weight loss and poorer overall body condition 
  • Poor appetite or ‘picky’ eating 
  • Behavioural changes – in horses with stomach ulcers they can appear more ‘grouchy’ than usual or ‘aggressive.’ They may also display grouchy behaviours when riders are mounting them or fastening/tightening up the girth, as this applies direct pressure to the front of their abdomen where the stomach is located.  
  • Poor performance (usually when ridden) – poor performance can include reluctance to go forward, bucking and unwilling to maintain canter. 
  • Colic (often recurring) or signs of abdominal pain 
  • Diarrhoea 

Please contact your Veterinarian if you recognise any of the above clinical signs in your horse. 

How are gastric ulcers diagnosed? 

Diagnosing equine stomach ulcers is usually a straightforward process and the best way to obtain a diagnosis is to perform a gastroscopy under sedation. Your Vet will insert a camera up your horse’s nose, and down via the oesophagus into the stomach to visualise the diseased gastric mucosa. To obtain the most accurate diagnosis, it is important to starve your horse prior to this procedure so that your Vet can obtain a clearer view of the whole stomach and it is not obscured by food material: your vet will advise you on how long for. Your Vet will grade the ulcers and the grade given is dependent on the severity, location, appearance and distribution. Your Vet will also take a thorough history and will perform a full general clinical examination to assess their overall health.  

How do we treat them? 

In order to achieve better treatment success the primary cause for EGUS would ideally be identified. But, this is not always a possibility. As well as management and husbandry changes your Vet will likely prescribe some medication.  

Medications for EGUS aims to suppress the gastric acid secretion and this is usually achieved with the active ingredient omeprazole which is a proton-pump inhibitor. Cleverly, this stops the pump in the stomach wall from producing acid.  

The equine forms of these medications come in an easy to administer syringe or in gastro-protectant granules, and the majority of horses will tolerate administration of one or both forms. Often treatment duration is around 4 weeks and your Vet will provide guidance on dosing instructions. 

These are all prescription-only medicines, but we stock all three major brands and can dispatch them to you on receipt of your vet’s prescription. 

In addition, there are products that aim to support a healthy stomach, such as Protexin Acid Ease. This is a palatable powder supplement containing a blend of probiotics, prebiotics, antacids including calcium and magnesium carbonates), kaolin, fibre and amino acids. These together act to buffer excess stomach acid and support the gut lining.  

Other management considerations 

Aside from medication, there are management changes which can positively support a horse with EGUS and here are just a couple of examples.  

As mentioned earlier, saliva acts as a buffer for stomach acid. If horses are starved for long periods of time, then their stomach acid does not get buffered and therefore remains very acidic. Therefore, increasing their forage intake and feeding frequency can be extremely beneficial. Forage, including hay, grass, fibre, and chaff, should always be the most important component of any horse’s diet.  

Additionally, if your horse is at risk of EGUS, it is sometimes advisable to also reduce the starch and sugar content of their hard feed which is achieved by removing the cereal part of their diet. Speak to your Vet or equine nutritionist for more guidance on this. 

Also, horses with EGUS or at-risk horses should be turned out to pasture as much as possible and stress related factors should be kept to a minimum. 


Gastric ulcers are debilitating, and they can negatively affect their health and wellbeing. Please seek Veterinary advice if you are concerned that your horse may have a gastric ulcer. We know that prevention is always better than cure so we must aim to manage and care for ‘at-risk’ horses appropriately and sensibly to try to avoid recurrence.   


Stefanyk, O. Slivinska, L. 2018. Equine gastric ulcer syndrome (EGUS). Prevalence, aetiology, diagnostic. Scientific messenger of LNU of Veterinary Medicine and Biotechnologies. 20: 83.