Ulcers in Horses

Ulcers in horses (also known as Equine ulcers) are a common ailment experienced by horses of all types. These can cause the horse serious discomfort and lead to a host of health issues, especially if bleeding occurs.

In this article, I will be going over what causes ulcers in horses, simple measures you can take to help prevent ulcers, and common horse ulcer symptoms and treatments.

What Causes Equine Ulcers?

While we do have a good idea of what contributes to ulcers in horses, it is definitely not a complete picture.

Right now, most researchers agree that the major cause of stomach ulcers in horses is periods of fasting or intermittent feeding. Horses, unlike humans, need to graze as their stomach constantly produces stomach acid. If horses fast for extended periods of time, the pH in their stomach decreases. This is especially the case of daytime and evening fasts; nocturnal fasting does not seem to have as strong of a negative effect on a horse’s stomach (1).

If you do not know, the lower the pH of a solution is, the more acidic it is. If a horse goes without food for long periods of time, the pH of its stomach can drop to harmfully low levels. Researchers of equine ulcers are able to regularly induce them by intermittent fasting protocols (2). As a result, a horse should always have access to food during the day and evening hours.

This is interesting as stomach ulcer symptoms in humans are generally caused by H pylori bacteria. In horses, this is not the case, as most studies are unable to find H pylori or even any Helicobacter types of bacteria colonizing the stomachs of horses (3,4). Occasionally an H-pylori relative turns up in horses but this is rare, especially compared to humans where almost all ulcers are concurrent with H pylori infection.

However, we cannot rule out the possibility that bacteria contribute to ulcers in horses. One study reported that a particular bacterium known as E. fergusonii may be associated with gastric ulcers in horses (4). This is an interesting development and one that requires more research in the future.

Ulcers in horses tend to be chronic and come and go frequently, even with treatment, over the course of a horse’s lifetime. If further research unveils a specific bacteria which may be causing these ulcers, then the efficacy of equine ulcer treatment should increase as well.

Symptoms, Diagnosis and Treatment of Equine Ulcers

As a horse cannot speak, the symptoms of horse ulcers are hard to identify. Generally, the most common symptom is colic (abdominal pain), along with loss of appetite, weight loss, and sluggishness. However, some horses will have no symptoms at all.

Equine ulcers are diagnosed by a veterinarian performing an endoscopy. This is a fairly inexpensive procedure and involves navigating a camera into the horses stomach (via the mouth) to check for ulceration. The horse is sedated for this process. Endoscopy is fairly inexpensive and most vets will be able to perform this procedure; do not assume your horse has an ulcer and begin treatment and instead let a veterinarian examine your animal.

Equine ulcers are usually treated with proton-pump inhibitors, much like humans. Humans receive these in pill-form whereas horses typically receive injections. Proton-pump inhibitors reduce the secretion of stomach acid and promote ulcer healing.

As research advances, hopefully we will get a clearer insight into what other factors can influence the formation of ulcers in horses. These advances will be key in developing new treatments for combating the prevalence of equine ulcers.


1. Husted L, Sanchez LC, Baptiste KE, Olsen SN. Effect of a feed/fast protocol on pH in the proximal equine stomach. Equine Vet J. 2009 Sep;41(7):658-62.

2. Morrissey NK, Bellenger CR, Ryan MT, Baird AW. Cyclooxygenase-2 mRNA expression in equine nonglandular and glandular gastric mucosal biopsy specimens obtained before and after induction of gastric ulceration via intermittent feed deprivation. Am J Vet Res. 2010 Nov;71(11):1312-20.

3. Martineau H, Thompson H, Taylor D. Pathology of gastritis and gastric ulceration in the horse. Part 1: range of lesions present in 21 mature individuals. Equine Vet J. 2009 Sep;41(7):638-44.

4. Husted L, Jensen TK, Olsen SN, Mølbak L. Examination of equine glandular stomach lesions for bacteria, including Helicobacter spp by fluorescence in situ hybridisation. BMC Microbiol. 2010 Mar 19;10:84.

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