Equine Gastric Ulcer Syndrome

Equine Gastric Ulcer Syndrome (EGUS)

'Gastric Ulcers' is an increasingly recognised term in the equine industry but is this down to increased prevalence or simply greater awareness and understanding? According to Richard Hepburn BVSc (Hons) CertEM (IntMed) Dip ACVIM MRCVS, Specialist in Gastroenterology, neurology and intensive care at B&W Equine Vets, the problem has been around for decades but due to lack of awareness and high cost diagnostic tools in the 90's and early 2000's, testing and therefore identification of gastric ulcers was limited, until recently. Now the disease is diagnosed as frequently as 1 in 3 horses with a much higher likelihood in racehorses than sport horses1,2. In today's blog, we break down the condition into need-to-know nuggets and look at how the development of ulcers can be prevented.

What are Gastric Ulcers?

Gastric Ulcers refer to sore and inflamed areas of the equine stomach which have been exposed to stomach acid over a prolonged period3. Like us, horses produce acid to assist in the breakdown of food in the stomach, however, while we are meal secreters and produce acid only during eating, horses are continual acid secreters and therefore produce acid continually, even when they are not eating. As a result, certain triggers lead to an excess of acid in the stomach or gastrointestinal tract and cause erosion of the stomach lining4. The erosion can vary in severity and is usually quantified using a 4 point scoring system3.

Types of Ulcers

The two most common types of ulcer relate to the name of the sections in the stomach where the ulcers are found; the glandular region and the non-glandular region (squamous). In the squamous region, ulceration is created when the mucosa is exposed to acid continually over a prolonged period (Equine Squamous Gastric Disease -ESGD). This type is seen more in racehorses and believed to be caused by the typical feeding and turnout practices of a racehorse in training. In the glandular region, despite a protective lining to protect the walls from a naturally lower pH as shown in the diagram below, ulceration can develop when the lining becomes compromised and occurs more commonly in sport horses (Equine Glandular Gastric Disease).5

 A write up from the European Society of Veterinary and Comparative Nutrition Congress (ESVCN) by Sharon Smith MSc SEBC(Reg) IEng BHSAPC.
An image by Sharon Smith MSc SEBC (Reg) IEng BHSAPC in a write up from the European 
Society of Veterinary and Comparative Nutrition Congress. 

How do I know if my horse is suffering from ulcers?

Clinical signs of the syndrome are commonly recognised from the following:1-4

Colic, Poor Appetite, Changes in coat, Abdominal Pain, Diarrhoea, Discomfort when tacking up/rugging, Changes in behaviour, Weight loss, Teeth Grinding and Poor Performance. However, not every horse fits this mould as stated by Richard Hepburn in a #HorseHour podcast on ulcers. Sometimes, signs of ulcers may simply be demonstrated by unusual behaviour for your horse such as a change in pace of eating their hard feed, leaving some feed or choosing hay or hard feed over the other. 

Diagnosing Ulcers

Diagnosing ulcers is a quick and painless procedure as it can be performed in as little as five minutes and involves a small sedation to prevent the horse from being nervous or reactive when the tube is inserted. Once inserted through the nostril, air is pumped into the horse’s stomach to allow for clearer views of the stomach and for images to be taken. Upon completion, the air is then taken out and the tube removed.6

A Gastroscopy being performed at Buckingham Equine Vets

In some instances, gastroscopy has been seen as controversial because it requires the horse to fast for at least 12 hours prior to scoping to allow for an empty stomach and ulcers to be seen. This in turn, allows acid to build up for a longer than optimal period which itself, is a cause of ulcers. This can be particularly conflicting as another gastroscopy is performed after a month of treatment to ensure ulcers have healed. However, most veterinary practices try to perform scoping in the morning so that the horse’s natural fasting period is only extended by a few hours. Furthermore, although bad for gut health, 12 hour fasting will only create ulcers after several days, not after one night6.

     Suggestions for an alternative diagnostic tool for ulcers have been attempted by Hewetson et al. (2017)7 who tested blood sucrose levels. However, this did not prove accurate or specific enough. Consequently gastroscopy is currently the sole diagnostic tool.  

Treating Ulcers

There are a few options for treatment but this depends on the type of ulcer. Quite often, the vet will prescribe an acid inhibitor called omeprazole or an antacid or coating agent supplement. It is also recommended to feed 50ml of corn oil, once or twice a day which has shown to reduce acid considerably in the stomach after 6 weeks8.

There are several gastric supplements on the market to improve gut health but these will only be effective for prevention and will not cure ulcers.

Following treatment or to prevent ulcers, new management practices should be deployed. These include:

  • Managing forage provision. It has been found that horses eat predominantly between 7am and 11pm and therefore consume less forage in the night. Advice from vets state that 80% of a horse’s daily intake should be fed within the daytime and the remaining 20% overnight when the horse is resting and sleeping. Increased access to turnout also reduced the risk of ulcers.8
  • Varying forage provision – Once the daily intake has been calculated and split between day and night, the ration should be split further between several haynets or feeding areas to allow the horse to move between them to keep fuller for longer. Free access to forage and reduced time between feeding (<6 hours) have widely reduced the risk of ulcers9.
  • Feed prior to exercise – Despite old myths and teaching to never feed before riding, contemporary research suggests feeding the right forage before exercising the horse helps to soak up stomach acid, consequently preventing the ‘splash effect’ whereby acid build up moves and ‘splashes’ around the stomach as the horse exercises. In general, the horse’s stomach contains 2-4L of acid all the time so feeding chaff approximately 30 minutes before riding helps to trap the acid and protect the stomach for up 2-4 hours8.
  • Similarly, feeding and watering after a ride will also help acid management. Unlike us when we exercise and blood moves from the stomach to the muscles, the horse’s blood supply to the stomach during exercise is maintained to sustain and even speed up gastric motility. Horses without access to water were considered 2.5 more times likely to develop ulcers9.
  • Some alternatives/additions to medication such as the administration of Aloe Vera have been suggested but the efficacy is yet to be examined. For more information on Aloe Vera as a treatment, click here for the latest study.
  • Where possible, avoid situations which cause your horse to become stressed as stress in both humans and horses have shown to increase stomach acid10,11
  • Horses prone to colic are also at risk of ulcers with 83% of colic cases diagnosed with ulcers in a study by Murray et al. (1992)11. If your horse is prone to colic, perhaps look at putting some preventative measures in place.


Further Listening / Reading

 Gastric Ulcers Explained: Richard Hepburn Podcast
 Gastric Ulcers Explained: Richard Hepburn Podcast

 Trackener Life kits enable monitoring of stress and detect the early signs of health conditions such as colic and ulcers. For more information and to order one for your horse click here.
Written by Ruth Box @ruth_box6910 Email Ruth


3Murray MJ, Eichorn ES. Effects of intermittent feed deprivation, intermittent feed deprivation with ranitidine administration, and stall confinement with ad libitum access to hay on gastric ulceration in horses. Am J Vet Res 1996; 57: 1599-1603.
4Sykes BW et al. Rethinking equine gastric ulcer syndrome: Part 1 – Terminology, clinical signs and diagnosis. Equine Vet Educ 2014;26(10):543-547.
6Horse Hour (2016). [podcast] Gastric Ulcers Explained: Richard Hepburn. Available at https://www.acast.com/horsehour/gastriculcersexplained-richardhepburn [Accessed 29 Nov 2017].
9Luthersson NNielsen KHHarris PParkin TDHRisk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in DenmarkEquine Vet J 2009;41:625630.
12Murray MJGastric ulceration in horses: 91 cases (1987–1990)J Am Vet Med Assoc1992;201:117120.


  1. Super post! I don't think people always understand that a change in lifestyle is the most effective way to prevent ulcers. As someone with an ulcer-prone horse, I'm giving this post a big thumbs-up!

    I like that you mention that there are many things on the market to prevent, but not treat ulcers. This is so true, and people really do need to engage their vet if ulcers are suspected. I think many horses suffer needlessly as owners try to find either a "natural" or a "cheap" way to treat them.

    I prevent ulcers in my mare by giving her a good probiotic daily, along with a product from Omega Alpha called Gastra-FX, which coats her tummy. But when I suspect a flare up, I immediately start a round of Gastrogard. It's the only thing that truly works (although my vet and I have found that we can treat with a smaller dose than the maker recommends - we usually only dose with half a tube a day rather than a full tube and find the results to be the same as with a full tube - this is helpful as it is a very expensive medication for sure.

    Thanks again for the super post!!!

    1. Thank you for your lovely long comment and feedback Pam! Prevention is always better than cure to keep our horses happy and healthy but unfortunately sometimes things are beyond our control in the more anxious horses. I'm really glad you've found a solution and formulated a routine to help keep your mare happy and thank you for sharing what works for you. Every horse is unique and so it's great to find a system that works for them. Good luck with keeping them at bay!

  2. This was a very interesting read. I did not know anything about horse stomachs and ulcers. Thank you for this article!

    1. Hi Amy, thank you for your feedback. I'm glad it helped you!

  3. Having worked with Racehorses for years, I have seen many miracles when ulcer treatment begins. I treated behavioral issues, such as stall walking, ill temper with gastro guard, or dosing ranitadine three times a day, it is effective, just not easy. This is very informative, and did not know that horses do not need as much at night. Makes sense.

    1. Hello, thank you for sharing your experiences with ulcers. I am not surprised you have seen it a lot in the racing world, research shows it can be as high at 90% in racehorses! I'm glad you found it a worthwhile read.


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