Horses evolved to ingest a high-fibre, low-starch ration on an almost continual basis. Foraging behaviour is important to the maintenance of a healthy digestive tract, as the chewing process produces large amounts of saliva which helps to buffer the acid that is produced in the horse's stomach.

The way in which we keep and manage our horses often means that they are unable to exhibit this normal foraging behaviour and are exposed to high stress levels such as during training or travelling, as well as being fed rations that may have high-cereal and starch levels with less than optimal forage.

These feeding and management practices have been associated with a high prevalence of Equine Gastric Ulcer Syndrome (EGUS). EGUS is a term that is used to describe ulcers in the terminal oesophagus, non-glandular and glandular regions of the stomach and the proximal duodenum. All ages and breeds of horses and ponies are susceptible to EGUS although it was thought to more commonly affect Thoroughbred racehorses. With the advancement of research and an increased ability to be able to study other classes of horses, EGUS has significant prevalence in other classifications of competition/leisure horses e.g. show horses, eventers, dressage and endurance horses. The common factor amongst these horses is that they are more likely to have reduced turnout, receive a lower forage intake and are exposed to higher stress levels due to more frequent travel and competition and are therefore also more likely to have irregular feeding patterns.

However, it is also becoming more apparent that EGUS can also affect leisure horses and we are certainly now dealingwith far more ‘leisure’ cases via our feed helpline. It has also been seen that all ages and breeds of horses and ponies aresusceptible to EGUS.

Stomach Graphic Ulcers have been identified throughout the stomach and the mostcommonly affected area is the non-glandular squamous mucosaalong the margo plicatus. Lesions that occur in the squamous areaof the stomach are usually a result of prolonged exposure, or‘splash’, from hydrochloric acid, to a poorly protected area of the stomach.

Prevalence of glandular mucosal lesions is certainly increasing asexpertise in the use of the endoscope rises and the lower part ofthe stomach is investigated more thoroughly. Glandular lesions arethought to result from impaired mucosal defence mechanismsrather than a primary peptic or acid injury. This is supported by theobservation that feed deprivation models used to create squamousinjury do not produce glandular lesions.

Glandular lesions can be successfully induced in horses using  excessive administration of non-steroidal anti-inflammatory drugs and there is  increasing evidence of a bacterial component to glandular ulcer development.


It has been suggested that EGUS should be divided into 2 distinct types

1. Primary squamous ulceration – resulting from an increase in acid exposure

2. Primary glandular ulceration – resulting from a failure of the mucosal defences


Pasture Turnout 

  • In general, grazing horses appear to have a reduced prevalence of EGUS. Horses that are allowed to be horseswill trickle feed and freely exhibit their natural feeding behaviour, therefore chewing frequently allowing for thecopious production of saliva to buffer the continual acid production in the stomach.

Forage Feeding 

  • When fed hay and pasture, horses produced 400 - 480 grams of saliva per 100 grams of dry matter consumed,whereas when a concentrate feed was fed, horses produced half as much saliva, therefore significantly reducingthe buffering capacity.
  • Alfalfa increases the buffering potential due to its higher calcium concentration.
  • If straw is fed as the sole forage source, an increase in gastric lesions has been observed possibly due to lowprotein and calcium content, and the coarse nature of the straw may increase gastric irritation.

Starch Intake 

  • Cereal and starch intake has been associated with an increased risk of EGUS in horses. Exceeding 2g/Kgbodyweight (BW) of starch intake per day was associated with a two fold increase in the likelihood of EGUS andfeeding more than 1g/Kg BW of starch per meal was associated with a 2.6 fold increase in the likelihood of EGUS.


  • Horses evolved to trickle feed and therefore almost continuously eat and chew and produce continual butvarying amounts of gastric acid. Chewing produces saliva, an important buffer of stomach acid. Withholdingfeed, even if for a short time, causes a rapid drop in gastric pH.
  • Gastric ulceration can be induced by alternating 24-hour periods of feed deprivation and ad-libitum access tohay for a total of 96 hours of feed deprivation. Feed deprivation reduces the amount of saliva production andfeed ‘matting’ to protect the squamous mucosa.


  • Workload has been suggested to be one of the most important risk factors for EGUS. It is suggested thatcontraction of the stomach during exercise allows acid from the glandular mucosa to reflux up into thenon-glandular region of the stomach resulting in acid injury to a relatively unprotected mucosal lining. Lessmarked injury has been seen in horses that have been fed prior to exercise.

Age, Breed, Gender

  • Some studies have shown an increase of EGUS in younger horses, aged 2 - 6 years, although this was confinedto racehorses, while other studies have shown that the risk increases as age increases. A study in leisure horsesshowed no association between age, breed and gender.

Other Risk Factors

  • Water deprivation
  • Electrolyte administration
  • Administration of NSAIDS
  • Reflux of bile acids
  • Bacterial contamination


The clinical signs of EGUS can vary from horse to horse and can also be a reflection on that individual horse’s temperament. Some horses will show more outwardly obvious signs with mild ulceration while others may show limited signs even in the presence of substantial ulceration. Personal observation has shown that horses with glandular lesions tend to have less tolerance than non-glandular ulcers.

Typical signs include:

  • Poor appetite or change in eating behaviour
  • Weight loss or failure to thrive
  • Irritability and general changes in temperament
  • Reduced performance
  • Abdominal discomfort to girthing or grooming
  • Recurrent mild colic


The only reliable method of diagnosis is by use of an endoscope. For this procedure to be carried out successfully feed needs to be withheld for 12 hours to allow for sufficient gastric emptying. A scoring system is used to score the lesions according to the number of lesions and their severity.

Medical Treatment 

Your vet is the best person to discuss treatment protocols with, but generally the treatment involves the use ofmedications such as Omeprazole and coating or binding agents to help protect the stomach lining.


  1. Horses should ideally be allowed ad-lib access to long forage or fed at least no less than 1.0 Kg/ 100 Kg BW
  2. Good doers or horses that are resting or in light work may benefit from a reduced DE content forage source or alow-calorie forage replacer. Straw can be used to dilute the hay or haylage ration but should not exceed morethan 25% of the forage ration.
  3. Restrict cereal and starch intake and ideally feed less than 2 g/Kg BW starch per day and less than 1g / Kg BW permeal. Feeds such as Re-Leve®, Super Fibre Cubes, Shape-Up™ and Competition-Fit Balancer are all suitable feedsfor the management of horses with EGUS.


Re Leve EGUS small


RE-LEVE® is a cereal-free, high-energy, high calorie mix designed for horses that react to a cerealbased diet. It is suitable for horses at every level and can be used to provide additional calories forweight gain or for additional energy for horses in harder levels of work. Soya hulls, alfalfa pellets andbeet pulp supply ‘super-fibres’ and oil as the energy sources, ensuring starch levels are kept to aminimum.


Super Fibre CUBES render


SUPER FIBRE CUBES are a high fibre feed formulated to be cereal-free and low starch and sugar. ‘Superfibres’ such as soya hulls and beet pilp provide sources of readily digestible fibre and the addition ofsoya oil supports optimal skin and coat condition. Super Fibre Cubes are also a great way to increasethe fibre content of any horses diet and can be fed sprinkled through hay or in a treat ball to stimulatenatural foraging behaviours.


Shape Up small


SHAPE-UP™ is a cereal-free, low starch, high fibre mix designed to provide a balanced diet at low intake levels, making it ideal for good-doers in work that are prone to metabolic disorders. For horses suffering with, or prone to, gastric ulcers Shape-Up™ contains an Acid-Buf that has been shown to restore and maintain correct pH in thestomach and hindgut environments.


Competition Fit Balancer Render HighRes


 COMPETITION-FIT BALANCER contains the optimum inclusion of a live yeast as well as Acid Buf, amarine derived buffering agent which through feeding trials has been proven to help support anoptimum pH in both the stomach and hindgut environment, as well as supporting the healingprocess of both squamous and glandular ulcers. The use of a live yeast has also been shown to helpsupport feed and forage digestibility, as well as maintaining a stable hindgut microflora populationduring times of stress. Competition-Fit Balancer is flavoured with spearmint and natural mint herbto keep tempting the appetites of fussy eaters.


4. Consider adding some alfalfa chaff to your horse's feed to increase the buffering potential of the ration. 100-200 grams/ 100 Kg BW is suitable

5. If your horse requires more calories in the ration to support body condition consider 'topping up' the ration withEQUI-JEWEL®, a high fat, rice bran supplement which boosts the calorie content of the ration without excessive cereal intake and without increasing the meal size

Equi Jewel WebsiteEQUI-JEWEL® is pelleted, high oil, stabilised rice bran supplement designed to increase the energy density of the whole diet, thereby decreasing the reliance on cereals in the diet.  EQUI-JEWEL® is also an ideal product to improve topline and condition on your horse. The essential fatty acids contained in EQUI-JEWEL® are necessary for healthy coat and skin condition. In addition to improved condition, research has proven its superiority in optimising performance. EQUI-JEWEL® is fortified with the correct level of Vitamin E and ensures optimum calcium to phosphorus ratio

6. When adding additional liquid oil to the ration, make sure that you check the antioxidant status ofthe ration e.g. Vitamin E.

7. Provide as much pasture turnout as is practically possible

8. Provide constant access to water

9. Look at ways of helping to reduce stress levels.RiteTrac SmallBucket small

10.Consider using antacid supplements such as KERx RiteTrac™ to help protect the digestive systemfrom gastric lesions. RiteTrac™ is a proprietary blend of ingredients with fast acting antacids,buffers and coating agents to help optimise pH in the stomach, as well as the inclusion of ahindgut buffer to aid digestion. Available as a powder in 3kg and 6kg tubs, RiteTrac can be simplyadded to feed at a rate of 120g/day – 60g in the morning and 60g in the evening.


A combination of preventative and therapeuatic treatments may be needed to prevent or manage gastric ulcers. 

For a personlised feeding plan for your horse complete our free online Feed Advice Form and a member of our nutritional team will compile a detailed report for you, or alternatively, you can speak to one of our qualified nutritionists for some immediate advice on 01622 718 487