Gastric Ulcers In Horses

By Gail Sramek BApplSc Agr


We are receiving more and more inquiries from horse owners and trainers inquiring about  remedies and feeding and management techniques to reduce and resolve the incidence of  ulcers.


Horses that are in training appear to suffer more from ulcers and the severity of ulceration  increases as the training period progresses. Some studies have reported 90% of racehorses  in intensive training suffer from ulcers. 75% of actively competing 3 day event horses and 58% of show horses were shown to be suffering from EGUS, Equine Gastric ulcer Syndrome  in ulcer studies. Foals and young growing horses can also be affected by ulcers. A foal will  start to secrete gastric acid, which has a high concentration, from 2 days of age onwards. 51% of foals and 84% of yearlings that were scoped in a study showed signs of gastric ulceration and this can be a contributing cause of death in foals.


How It All Begins

EGUS, Equine Gastric Ulcer Syndrome is the term used to describe the formation of ulcers  (the breakdown of the tissue lining) throughout the terminal end of the oesophagus, the glandular and non-glandular parts of the stomach and the earlier section of the small  intestine known as the duodenum.

As the ulcer worsens there is an increase in the number of lesions and the depth of the  lesions. The ulcers are graded depending on their severity. MacAllister and his associates have devised a grading system as follows:


GradeNumber of lesionsSeverity
11-2 localised lesionsAppears superficial
23-5 localised lesionsDeeper structure involved (more than mucosal)
36-10 lesionsMultiple lesions and variable severity
4>10 lesionsSame as Grade 2 but with an active appearance
5N/ASame as Grade 4 but with active haemorrage or adherent blood clot

(Ref: MacAllister et al 1997, A Scoring System for gastric ulcers in horses. Equine Vet J 29, 430-433).


Fig 1: A severely ulcerated stomach. Ref: Risk Factors for Gastric Ulceration in Thoroughbred Racehorses RIDIC 08/061. Based on the above table we would classify this ulcer as Grade 4-5.



Horses that have ulcers or EGUS may display the following symptoms:

  • Reduced feed intake or poor appetite
  • Loss of condition
  • Rough or poor hair coat
  • Poor performance
  • Changes in behaviour and attitude – this may be either an increase in fear and  flightiness or dull and quiet.
  • Abdominal discomfort – the tightening of the girth may show signs of discomfort. Some horses may stretch more and urinate more often.



If you think your horse may have an ulcer the best way to accurately diagnose it is by  gastric endoscopy. This is generally performed by a qualified equine veterinarian. Your  vet will insert a tube with a camera and light at the end which enables him to be able to  look at the surface of the esophagus, the glandular and non-glandular areas of the  stomach and the first part of the small intestine to accurately evaluate if your horse has  ulcers and what grade they are. To keep your horse calm, a mild tranquiliser is often  given and the full procedure takes around 10-20 minutes.


Contributing Factors to Ulcers

The development of ulcers can be a combination of management practices which  contribute to the deterioration of the mucosa in the digestive tract.



The workload of a horse is one of the higher contributors to ulcers  in horses. It is thought that ‘gastric splashing’ may be a contributing factor to this. The  stomach is split up into two main sections, the glandular mucosa and the non-glandular  mucosa. Gastric splashing occurs when the stomach contracts during exercise allowing  the acid from the glandular mucosa to splash up onto the unprotected non-glandular  mucosa. The following cross section of the stomach estimates the areas in the non glandular  and glandular mucosa that are affected by gastric ulceration.


Fig 2: The horse’s stomach giving an estimated distribution of gastric ulcerations in the non-glandular and glandular mucosa.


The risk of developing ulcers can be apparent in horses in training in as little as eight  days. A study on racehorses in Australia has suggested that the prevalence of ulcers increased by 1.7 times for every week the horse was in training. This could be partly due  to the fact that the pH of the stomach becomes more acidic during work, although this  can be reduced if the horse is fed before exercising.



Horses have evolved to eat for up to 16 hours per day and their digestive tract has been designed to have access to a constant stream of feed. The horse’s stomach constantly secretes gastric juices, the liver constantly secretes bile and the pancreas Glandular mucosa Contributing Factors to Ulcers Non-glandular mucosa 64% 25% 2% 15% 2% 1% constantly secretes pancreatic juices into the duodenum (the first part of the small intestine). When feed is withheld from horses whether it is from poor feeding management or prior to racing the pH of the gastric juice drops to 2.0 or less. This can be compared to horses that were fed free choice Timothy hay that had a gastric pH of 3.1. Once the pH of the gastric juice drops the non-glandular part of the stomach is more susceptible to ulceration.



Although not always practical, training horses from the paddock can minimise the incidence of ulcers. Racehorses that have access to sometime of free grazing have a decreased incidence of ulcers. As horses chew pasture, they produce saliva which has a high bicarbonate level, buffering the strong acid environment in the stomach. When horses are put out with a buddy the incidence of ulcers is again reduced. In a study, it only took seven days for lesions to develop in horses that were stabled with free access to hay.



Horses fed a high starch diets have an increased number of microorganisms in the stomach, causing fermentation of starches, producing a more acidic environment that can lead to stomach ulceration. Keeping the starch level to less than 2g/kg bodyweight intake per day or 1g/kg bodyweight of starch per meal can help to minimise ulceration.



Ideally all horses should receive a minimum of 1% of their bodyweight in roughage (dry matter) per day. A horse should produce approximately 12 litres of saliva per day. As saliva has a high bicarbonate level and high pH it helps to buffer the acidic environment in the stomach.

Chewing stimulates the production of saliva and the amount of chewing required depends on the type of feed the horse is eating. 1kg of long stem hay can take 3000- 3500 chewing movements to consume compared to a concentrate that may require 800-1200 chewing movements to consume 1kg. Providing long stem hay available ad libitum will maximize the amount of chewing and production of saliva to reduce an acidic environment in the stomach.

The type of roughage fed can affect the degree of ulceration. If straw is the only forage fed the chance of a grade 2 or greater non-glandular gastric ulceration is increased by 4.5 times. Feeding Lucerne hay with grain may increase the pH of the stomach compared to feeding some types of grass hay (Brome Grass hay or Coastal Bermuda hay) fed without grain.



Rations that are fed in greater than 6 hourly intervals increased the possibility of the development of ulcers compared to feeding in less than 6 hourly intervals. Therefore feeding 4 meals per day to horses with ulcers and providing ad lib hay may minimise ulcer development.



Non Steroid Anti-Inflammatory Drugs (NSAID’s) have been shown to induce glandular lesions when administered to horses and an increased risk of gastric ulceration has been linked to their use. These drugs include phenylbutazone and flunixin meglumine. Horses appear to respond differently to these drugs and caution should be used when treating horses depending on the dose level and duration of the treatment. We suggest consultation with your equine veterinarian if you are using these drugs.



When transporting horses, care needs to be taken to keep feeding and watering regimes consistent. Studies have shown paddocked horses without ad lib access to water are more likely to develop ulcers and regular feeds are important to minimise an acidic environment in the stomach.



A study on endurance horses showed that horses administered electrolyte paste by dose syringe resulted in a significant increase in ulcer numbers and severity when compared to placebo administration. When the electrolytes were given in low doses in water or mixed in the feed there was not an increase in ulceration.


Prevention & Treatment of Ulcers

Prevention is better than cure and by incorporating some feeding and management regimes the incidence of ulcers can be minimised.



  • Feed 3-4 meals per day if the horse is not on pasture. Ad lib hay can be provided to make up for the short fall between feeding times.
  • Provide ad lib hay if the horse is stabled or pasture is limited. Provide a high calcium, high protein forage such as lucerne hay, although the ration should be a mix of Lucerne and grass/oaten hay or pasture. Don’t feed straw as its low calcium and protein level result in a poor buffering capacity. Ideally the ration should contain 75% roughage to keep the pH in the stomach within a normal range.
  • Feed a small feed of lucerne and hard feed prior to work to increase the pH in the stomach.
  • Reduce the amount of high starch grain in the ration.
  • Free access to paddock time on pasture – this allows the horse to constantly forage to keep gastric acid levels low.
  • If anti-inflammatory drugs need to be administered NSAID’s such as Firocoxib and Ketoprofen may be proposed as they have a smaller effect on the digestive tract compared to other anti-inflammatory drugs. Your equine veterinarian may consider using an anti-ulcer medication in conjunction with anti-inflammatory drugs to minimise the incidence of ulcers.
  • Stressful situations such as intense training and transport should be limited. Turn off the radio at the stables. Horses don’t listen to the radio in the wild.
  • Allow your horse to socialise and see other horses.
  • Use feeds that have a steam–extruded component and feeds which have been processed in such a way that eating is slower, resulting in more chewing, increased saliva production and higher saliva bicarbonate levels. i.e FORMULA 3.
  • Include protectants such as gamma oryzanol in the daily diet. SUPER AMINO 66 and ANAZOLIC contain gamma oryzanol.
  • Medical Management – If your horse is diagnosed with ulcers your equine veterinarian may suggest an equine specific form of Omeprazole fed at recommended rates. Such a Gastrogard or Ulcergard.


There are a variety of factors that can contribute to the incidence of ulcers. By providing suggested feeding and management practices the digestive environment can be improved to minimise the occurrence of ulcers helping to improve the wellbeing of horses and their performance. Contact Mitavite on 1800-025-487 or email us for more information on feeding horses with ulcers.