Equine Gastric Ulcer Syndrome


Equine gastric ulcer syndrome

In the last few years the recognition of equine gastric ulcer syndrome (EGUS) has become more commonly identified amongst the horse population with the greater accessibility of video gastroscopy.

It has been a difficult condition to identify by its clinical signs as they are not unique to EGUS and are often subtle. It is however a significant disorder affecting performance, appetite and temperament.

The incidence in racehorses has been found to be over 80% and in competition horses up to 70%. It is the most common disease of horses but still greatly under-diagnosed.


Following treatment most horses show a big improvement in performance (improved placing of horses/wins in races), better temperament (decreased bucking, more placid under saddle, less aggression), better appetite and improved condition.

Why does it happen?

Gastric ulcer syndrome in horses

The horse in its natural environment should spend up to 16 hours per day feeding in a herd, with the occasional need to move at high speed to evade predators. In this state the horse’s naturally acidic stomach contents are buffered by saliva produced in response to regular eating. With normal gentle relaxed movement, the gastric contents generally are restricted to the lower glandular part of the stomach rather than the upper part lined by stratified squamous epithelium. The glandular part of the stomach is protected by a mucous/bicarbonate protective layer, rapid cell turnover, prostaglandin and intracellular tight junctions. The upper stratified squamous epithelium lacks these defensive mechanisms but in the natural situation rarely comes into contact with the acidic stomach contents.

By domesticating the horse we have:

  1. Reduced the time that it spends eating – decreasing saliva production
  2. Regularly exercised the horse – splashes contents around the lining and reduces blood flow to the wall
  3. Reduced the amount of forage in the diet and restricted feed intake

These factors lead to EGUS.

Clinical Signs

As mentioned above the clinical signs are variable and often subtle and may well be shared with a number of other conditions. The symptoms may include one or more of the following symptoms:

  • Poor performance
  • Reduced appetite
  • Altered temperament – difficult to ride, bucking, refusing at jumps
  • Weight loss
  • Teeth grinding
  • Colic
  • Diarrhoea
  • Crib biting
  • Back pain
  • Peritonitis and death


Diagnosis of Equine Gastric Ulcer Syndrome


The only accurate method of diagnosis and monitoring of the condition is by gastroscopy. Patients should be starved for 12 hours before this procedure and their water supply should be removed 4 hours beforehand. During the examination the horse’s oesophagus, stomach and proximal duodenum are visualised and inspected. Ulceration is graded on a scale of 1 to 4 with 1 being mild thickening only to 4 being deep widespread ulcers. Bleeding does not relate to the depth or the severity of the ulcer. It is important to assess the stomach by gastroscopy, to confirm the presence of ulcers to avoid treating unnecessarily.


Below are a series of images showing common findings on gastroscopy.

Equine Gastric Ulcer Grade1


Grade 1 ulceration with thickening and roughening of the upper part of the stomach (squamous mucosa) indicated by an arrow.


Equine Gastric Ulcer Grade2


Grade 2 ulcer adjacent to the margo plicatus (arrow). It is a single circular area, discretely isolated.


Equine Gastric Ulcer Grade3


Grade 3 ulcers adjacent to the margo plicatus. Although there are multiple ulcers they are distinct from one another.


Equine Gastric Ulcer Grade4


Grade 4 ulcers. Adjacent ulcers are merging to form a large ulcerated area


Equine Gastric Ulcer Pylorus


Grade 2 ulcers around the pylorus at the exit to the stomach.


Equine Gastric Ulcer Bots


Bot larvae are a common finding in the stomachs of horses, especially in winter



The licensed veterinary medicine is Gastrogard, a proton pump inhibitor, which has proven most effective in clinical trials. Other drugs used include cimetidine and ranitidine, H2 receptor antagonists, and sucralfate, a mucosal binding agent. In addition to medication, careful assessment of diet, management and exercise regimes should be made to prevent recurrence. As medication is quite expensive it is necessary to re-examine endoscopically to ensure resolution of the ulcers.

Case Report 1

Star was a 12 year old Irish Sports Horse used for riding club dressage and hunter-trials and had been in the current ownership for the last five years. On her annual vaccination she was noticed to be quite light weight and she had not completely finished her hard feed. On questioning the owner, she reported that this was normal for Star. In addition to this she was also a wind-sucker.

As the symptoms were suggestive of gastric ulcer syndrome, the owner decided to have Star gastroscoped. When examined, Star was found to have multiple grade 2 ulcers throughout the stomach both around the margo plicatus and at the pylorus. She was started on a four week course of Gastrogard. In addition, she was given ad lib access to hay and her feeding frequency was increased to four small feeds per day.

She was gastroscoped again four weeks later. At this examination the ulcers were found to have resolved completely. The owner reported that she was now eating her hard feeds up completely and rapidly. She also commented that she had stopped bucking when being jumped which she had been doing for the last five years and the owner thought was just her normal behaviour!!! On examining her for an unrelated matter six months later she had increased in body weight significantly despite having no increase in total feed amount.

Case Report 2

A racehorse trainer who trained both Flat and National Hunt horses requested to have a number of his horses gastroscoped. He had only had two winners in the last six months and twelve horses placed. Blood samples had shown some horses had a mild anaemia and occasionally mildly elevated liver enzymes. The trainer thought that the problem was a “virus” in the yard. The assistant trainer reported that some of the horses had poor appetites especially after running in races.

On the initial visit twelve horses were gastroscoped. All of these twelve showed evidence of gastric ulcers varying from grade 2 to grade 4 (an incidence of 100%). The management of the horses was discussed resulting in increased feeding frequency and increased haylage being fed. The worst affected horses were placed on a 4 week course of gastrogard. Repeat examinations of these and other horses on the yard continued over the next 2 years. The incidence of gastric ulcers decreased over this period to the point where approximately 40% of endoscoped horses had evidence of ulcers and these were generally not worse than grade 2.

Over this period, the results from the yard’s runners improved dramatically. In the following 12 months, there were 12 winners and 27 horses placed. Although in a racing situation it is impossible to completely eliminate gastric ulcers, their management is critical to the optimum performance of racehorses.

If you would like to discuss gastric ulcer syndrome the please contact Mark or Anna at the surgery.

Scott Dunn’s Equine Clinic is part of CVS (UK) Limited, a company which owns over 300 veterinary practices in the UK. Company Registration Number 03777473. Registered Office CVS House, Owen Road, Diss, Norfolk, IP22 4ER