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Gastric Ulcers - Focus on Prevention

03/04/2012 by Amanda Warren-Smith

Equine Gastric Ulcer Syndrome (EGUS) is a condition that affects a large proportion of racing and performance horses. This article focuses on prevention and is based on much of the extensive peer reviewed research to date (2011). 

In this article Amanda Warren-Smith has reviewed the Scientific practical management  strategies of EGUS.

EGUS prevention is possible by keeping horses on pasture all day and all year, and lowering the stress caused by training, that is: keeping it correct, calm and consistent, monitoring behaviour so you can respond appropriately as soon as you notice the first signs of conflict. 
The high prevalence of gastric ulcers is a concern not only for the health of the horse, but it may also have a significant economic impact, with reduced earnings due to diminished performance and high costs associated with therapeutics and prophylactic medication.
Spontaneous healing of gastric ulcers in horses that are actively being worked is rare(1,2) indeed they are more likely to continue to worsen if the horse is kept in work(3). Treatment currently involves pharmacological suppression of gastric acid secretion and treatment must be continual whilst horses are in training to prevent recurrence(4). The oral administration of omeprazole has been shown to be effective in both treating horses with gastric ulceration and at preventing re-occurrence whilst the horses are in training, provided that daily dosing is maintained(5-9).
In the interests of the horse’s welfare, dietary and environmental modification will also help healing10, for instance, taking horses out of work for a period and turning them out to pasture has been suggested as the best dietarymanagement treatment for EGUS(11).


One study of competition horses showed that after three consecutive days of travel and competition 56% developed ulceration(14). 


Ensuring that our training follows the principles of learning theory and that we are consistent with our application of stimuli and reinforcement. Using progressive habituation to get horses used to the many different situations that they may be faced with in training gradually, rather than over-exposing them to too many things concurrently.
Benchmark relaxation: Do not progress with training until the horse shows that it is ready i.e. no conflict responses at all in earlier training sessions.
If you wish to take them out to competitions of any kind, then start slow and progress gradually to any other events. This may mean that the first few events are actually only short trips to someone else’s property so that there is not too much stress upon arrival. Then possibly progress to small outings e.g. perhaps visit the local dressage club before going to some busy Agricultural show.




Gradually habituate the horse to transportation, teach them to be calm when entering the float/truck, progress 1 step at a time, doing this as slowly as necessary.
Take them on only very short trips initially and always drive extremely carefully, make the trip as smooth as possible and do not incite stress upon reaching the destination.
Do not only subject them to travel rarely, if it is something that you would like to do with regularly then do not only train the to the float once a year or so, train this response regularly as you would any other response.


Dietary influences such as high-energy feed17, feeding grain(18), type and amount of roughage fed(19-21) and intermittent feeding(10,16); horses have evolved to graze continuously and any changes to this grazing pattern increases the risk of digestive problems including EGUS.


Keep their diet as close to what is natural for them as possible i.e. ensure adequate grazing all year round.  If this is not currently possible then perhaps you need to make some major modifications to ensure that it is possible.
If you need to supplement their dietary intake then keep it as simple as possible; start with long roughage i.e. hay and make that a 50:50 mix of Lucerne and pasture hay and this needs to be available 24 hours a day to simulate grazing.


Confinement in stables(22) even when given ad-libitum access to hay(17), possibly because the confinement itself leads to decreased time spent eating compared with horses on pasture(23)


Do not lock horses up in stables or yards but allow grazing 24 hours of the day.


Intense exercise and racing(10,16) as well as prolonged training(22).  Horses in race training have been shown to have a higher prevalence of gastric ulcers than those not in work(3,22,24,25).  It was suggested that the increase in intra-abdominal pressure during exercise causes compression of the stomach, which in turn leads to exposure of the squamous portion of the stomach to acid26. The use of simulated race training, i.e. working between 1.6–3.4 km six times per week on a track, resulted in 100% of horses developing ulcers within 2 weeks of entering training; all horses in that study were stabled(4).


Take the time it takes to get a horse ready for intense training i.e. about twice as long as is usually considered ‘normal’ so do not expect them to reach race fitness in a matter of weeks, this takes many months. 
That said, do not expect to keep them in intense work for prolonged periods.
Pay very close attention to the horses normal behaviour and any changes it may show, no matter how subtle, this could be an indication that the horse is not coping with what you are doing and therefore you do not progress but rather slow down the progress.


Administration of non-steroidal anti-inflammatory drugs (NSAIDs) e.g. bute may contribute to horses developing EGUS(27) although its effects may be worse on those with existing ulceration(28).  To date, this has been the only documented cause of gastroduodenal ulceration in foals(29).


Use medications only when necessary and under veterinary guidance.


Certain bacteria(24)


Ensure that the horse is living in clean natural conditions.
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  • 2. MacAllister CG, Sifferman RL, McClure SR, White GW, Vatistas NJ, Holste JE, Ericcson GF and Cox JL. 1999. Effects of omeprazole paste on healing of spontaneous gastric ulcers in horses and foals: a field trial. Equine Veterinary Journal Supplement. 29:77-80.

  • 3. Murray MJ, Schusser GF, Pipers FS and Gross SJ. 1996. Factors associated with gastric lesions in Thoroughbred racehorses. Equine Veterinary Journal. 28:368-374. 

  • 4. Vatistas NJ, Sifferman RL, Holste J, Cox JL, Pinalto G and Schultz KT. 1999b. Induction and maintenance of gastric ulceration in horses in simulated race training. Equine Veterinary Journal Supplement. 29:40-44. 

  • 5. Haven ML, Dave K, Burrow JA, Merritt AM, Harris D, Zhang D and Hickey GJ. 1999. Comparison of the antisecretory effects of omeprazole when administered intravenously, as acid-stable granules and as an oral paste in horses. Equine Veterinary Journal Supplement. 29:54-58.

  • 6. Johnson JH, Vatistas N, Castro L, Fischer T, Pipers FS and Maye D. 2001. Field survey of the prevalence of gastric ulcers in Thoroughbred racehorses and on response to treatment of affected horses with omeprazole paste. Equine Veterinary Education. 13:221-224.

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  • 8. McClure SR, White GW, Sifferman RL, Bernard W, Doucet MY, Vrins A, Holste JE, Fleishman C, Alva R and Cramer LG. 2005a. Efficacy of omeprazole paste for prevention of gastric ulcers in horses in race training. Journal of the American Veterinary Medical Association. 226:1681-1684.

  • 9. McClure SR, White GW, Sifferman RL, Bernard W, Hughes FE, Holste JE, Fleishman C, Alva R and Cramer LG. 2005b. Efficacy of omeprazole paste for prevention of recurrence of gastric ulcers in horses in race training. Journal of the American Veterinary Medical Association. 226:1685-1688. 

  • 10. Buchanan BR and Andrews FM. 2003. Treatment and prevention of equine gastric ulcer syndrome. Veterinary Clinics of North America-Equine Practice. 19:575-597. 

  • 12. Murray MJ. 1994a. Gastric ulcers in adult horses. Compendium on Continuing Education for the Practicing Veterinarian. 16:792-794.

  • 13. Lloyd KC. 1993. Ontogeny of gastric function vs the ‘stress syndrome’. Equine Veterinary Journal. 25:179. 

  • 14. McClure SR, Glickman LT and Glickman NW. 1999. Prevalence of gastric ulcers in show horses. Journal of the American Veterinary Medical Association. 215:1130-1133.

  • 15. Hartmann AM and Frankeny RL. 2003. A preliminary investigation into the association between competition and gastric ulcer formation in non-racing performance horses. Journal of Equine Veterinary Science. 23:560-561.

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  • 18. Murray MJ and Eichorn ES. 1996. 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. American Journal of Veterinary Research. 57:1599-1603.

  • 19. Flores RS, Byron CR and Kline KH. 2011. Effect of feed processing method on average daily gain and gastric ulcer development in weanling horses. Journal of Equine Veterinary Science. 31:124-128. 

  • 20. Smyth GB, Young DW and Hammond LS. 1989. Effects of diet and feeding on postprandial serum gastrin and insulin concentration in adult horses. Equine Veterinary Journal Supplement. 7:56-59.

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  • 24. Murray MJ. 1994b. Equine model of inducing ulceration in alimentary squamous epithelial mucosa. Digestive Diseases and Sciences. 39:2530-2535.

  • 25. Murray MJ, Grodinsky C, Anderson CW, Radue PF and Schmidt GR. 1989. Gastric ulcers in horses: a comparison of endoscopic findings in horses with and without clinical signs. Equine Veterinary Journal Supplement. 7:68-72.

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  • 29. MacAllister CG, Morgan SJ, Borne AT and Pollet RA. 1993. Comparison of adverse effects of phenylbutazone, flunixin meglumine and ketoprofen in horses. Journal of the American Veterinary Medical Association. 202:71-77.

  • 30. Becht JL and Byars TD. 1986. Gastroduodenal ulceration in foals. Equine Veterinary Journal. 18:307-312