Equine Gastric Ulcers: Prevalence, signs and risk factors

Studies show gastric ulcers affect:

37% of untrained racehorses, rising to 93% after 2–3 months of training (Hammond et al., 1986; Murray et al., 1989, 1996; Vatistas et al., 1999; Begg & O'Sullivan, 2003).

Racehorses 93% of racehorses have stomach ulcers.

37% of pleasure horses (Murray et al., 1996).

58% of show horses (McClure et al., 1999).

50% of foals (Murray, 1999).

40% of Western performance Quarter horses (Bertone, 2000).

44% of Standardbred racehorses, rising to 87% in training (Rabuffo et al., 2002).

56.5% of horses in endurance competition, show jumping, dressage, or western performance (Hartmann & Frankey, 2003).

67% of horses competing in endurance rides (Neito et al., 2004).

66.6% of pregnant and 75.9% of nonpregnant broodmares (le Jeuine et al., 2009).

11% of rarely competed horses, predominantly used in a home environment (Chameroy et al., 2006).

48% of endurance horses during interseason, rising to 93% during the competition season (Tamzali et al., 2011).


Some possible warning signs of equine gastric ulcers are:

Behavioral changes:

  • A change in attitude — Is your horse more nervous than usual or less willing to perform? Does he seem grouchy or “out of it” for no apparent reason? Behavioral changes: nervousness, aggression, and self-mutilation, may be a clinical sign of equine gastric ulcers (McClure et al., 1999; Andrews et al., 1999; Nicol et al., 2002; McDonnell, 2008).
  • Does your horse appear to be preoccupied or unable to concentrate?
  • Is your horse less sociable than previously, or more needy?
  • Has your horse developed new or worsened barn manners?
  • Bruxism — Does your horse frequently grind his teeth, crib, or lash out in any way? (Bell et al., 2007)
    Horse cribbing A horse cribbing on a tree stump.
  • Picky eating — Is he eating as much as he normally does for the amount of work he’s accomplishing? Is he leaving any of his feed uneaten? Conversely, is your horse suddenly ravenous, seeming to demand more food? Poor appetite or ‘picky eating’ is commonly associated with equine ulcers (Murray et al., 1989; Andrews et al., 1999; Vatistas et al., 1993; Bezdeková et al., 2008).
  • Dullness — Is your horse generally lackluster and seemingly without energy?

Physical changes:

  • Decreased performance — Is your horse not as “fluid” as normal? Could his usually fine movement, speed or scope, be described as below average?
  • Weight loss — Has your horse dropped weight or has girth size changed? (Murray et al., 1989; Andrews et al., 1999; Dionne et al., 2003)
  • Colic — Is your horse showing signs of low-grade colic, a persistent mild discomfort that may cause him to turn his head toward his flank, lie down excessively, paw, or fail to finish a meal? 83% of horses with recurrent colic (Murray, 1990) and 49% with acute colic have gastric ulcers (Dukti et al., 2006).
  • A decline in body condition — Is your horse’s coat not quite as sleek and shiny as it once was? (Vatistas et al., 1999)
  • Does your horse have loose stools or constipation? Chronic diarrhea has long been associated with equine gastric ulcers (Murray et al., 1989; Andrews et al., 1999).
  • Does your horse have mild or severe anemia?
  • Does your horse stretch more often than usual to urinate?
  • Has your horse begun to lose hair, particularly facial hair?
  • Has your horse shortened its stride, particularly on the right rear? This is often one sign of a hindgut ulcer.
  • Is your foal doing poorly? 50% of foals develop gastric ulcers within the first few months of life (Murray, 1999).

However, many horses with gastric ulcers will not demonstrate any clinical signs (Andrews et al., 1999; Bell et al., 2007; Lutherson et al., 2009).


Potential causes, and risk factors:

Horse training Horses can develop gastric ulcers in as little as 8 days of intense training.

Intense exercise is perhaps the most common risk factor: horses can develop significant stomach ulceration within as little as 8 days of heavy training (Murray et al., 1996; Orsini, 2000; Lester, 2004; Chameroy et al., 2006; Jonsson & Egenvall, 2006).

Show horses with a nervous disposition are more likely to have gastric ulcers than quiet or normally behaved horses (McClure et al., 1999).

Transportation (McClure et al., 2005).

Stall confinement increases the risk of developing ulcers (Murray & Eichorn, 1996).

Confined horse Confinement increases the risk of ulcers.

Time in work, crib-biting, difficulty maintaining bodyweight, and even playing the radio in the barn have been identified as risk factors (Lester et al., 2008).

Horses trained in urban areas are 3.9 times more likely to have gastric ulcers; lack of direct contact with other horses; solid barriers instead of rails (Lester et al., 2008).

Horses without access to water in their paddock are more than 2.5 times more likely to develop gastric ulcers (Luthersson et al., 2009).

Use of electrolyte supplements increases the risk of developing gastric ulcers (Holbrook et al., 2005).

Horse drinking water Poor access to water increases the risk of equine gastric ulcers by 2.5 times.

High-grain, low-hay diets have been shown to increase the incidence of ulcers (Hammond et al., 1986), whereas free access to good quality pasture and a diet containing alfalfa hay can reduce the likelihood (Nadeau et al., 2000; Lybbert et al., 2007).

Large, high starch meals should be avoided in horses prone to gastric ulceration (Taharaguchi et al., 2004; Boswinkel et al., 2007). High starch diets empty from the stomach more slowly and are fermented, resulting in increased acid levels. High starch diets also tend to reflect a high cereal intake and more fluid gastric contents that may promote acid splashing (Argenzio, 1999; Lorenzo-Figueras & Merritt, 2002).

Horse eating hay Horses prone to gastric ulceration should avoid large, high starch diets.

Feed deprivation, i.e., more than 6 hours without food (Murray & Grady, 2002).

The use of NSAIDs (e.g., bute) have the potential to cause gastric ulcers, however this is usually related to the use of high dosages or frequent administration (Monreal et al., 2004; Reed et al., 2006).

Horses with bowel, liver, and oesophageal lesions have a higher prevalence of gastric ulcers (Sandin et al., 2000).

References ►

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  2. Argenzio, R. A. (1999) Comparative pathophysiology of non-glandular ulcer disease: A review of experimental studies. Equine Veterinary Journal Supplement 29:19–23.
  3. Begg, L. M., and O'Sullivan, C. B. (2003) The prevalence and distribution of gastric ulceration in 345 racehorses. Australian Veterinary Journal 81:199–201.
  4. Bell, R. J. W., Kingston, J. K., Mogg, T. D., and Perkins, N. R. (2007) The prevalence of gastric ulceration in racehorses in New Zealand. New Zealand Veterinary Journal 55:13–18.
  5. Bertone, J. J. (2000) Prevalence of gastric ulcers in elite, heavy use Western performance horses. Journal of Veterinary Internal Medicine 14:366.
  6. Boswinkel, A. M., Ellis, A. D., and Sloet van Oldruitenborgh-Oosterbaan, M. M. (2007) The influence of low versus high fibre haylage diets in combination with training or pasture rest on equine gastric ulceration syndrome (EGUS). Pferdehilkunde 23:123–130.
  7. Chameroy, K. A., Nadeau, J. A., Bushmich S. L. Dinger, J. E., Hoagland, T. A., and Saxton, A. M. (2006) Prevalence of non-glandular gastric ulcers in horses involved in a university riding program. Journal of Equine Veterinary Science 26:207–211.
  8. Dionne, R., Vrins, A., and Doucet, M. (2003) Gastric ulcers in Standardbred racehorses: Prevalence, lesion description, and risk factors. Journal of Veterinary Internal Medicine 17:218–222.
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  23. Monreal, L., Sabatè, Segura, D., Mayós, I., and Homedes, J. (2004) Lower gastric ulcerogenic effect of suxibuzone compared to phenylbutazone when adminisered orally to horses. Research in Veterinary Science 76:145–149.
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  32. Nicol, C. J. C., Davidson, H. P. D., Harris, P. A., Waters, A. J., and Wilson, A. D. (2002) Study of crib-biting and gastric inflammation and ulceration in young horses. Veterinary Record 151:658–662.
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  35. Reed, S. K., Messer, N. T., Tessman, R. K., and Keegan, K. G. (2006) Effects of phenylbutazone alone or in combination with flunixin meglumine on blood protein concentrations in horses. American Journal of Veterinary Research 67:398–402.
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