Monthly Topic: Ulcers

In January I began a new monthly feature as a way to tie some educational posts in with my story.

January we began with The Digestive System and Fast Facts About The Equine Digestive System. In February we zoomed in even more on the GI tract and focused on the Microbiome. Feel free to click the links to go back and see what you might have missed!

This month I am going into the digestive once more. Let’s talk about the popular subject of ulcers.

If you’re in any equine Facebook group you might have someone telling you that your horse has ulcers. He’s not eating? Ulcers. Lame? Ulcers. Chewing Wood? Ulcers. Tripped during your ride last night? Ulcers.

While I joke the truth is that many horses do or will have ulcers at some point in their lives. The modern methods for horse care simply do not take into consideration the horse’s biochemistry. Modern horse care is for people…not the horses. Today I’m not here to debate equine management, I’m just here to present you research and studies I’ve been reading.

It’s been said that 80% of equine ulcers occur in the upper (proximal) half of the stomach. Remember back to January the proximal half of the stomach does not have much protection from stomach acid. Excessive exposure to stomach acid can easily break down the epithelial layers and cause upset.

Modern horse-keeping generally has most horse owners feeding a commercial feed along with hay. Some people will feed their horses 8 pounds of “grain” in one meal. The problem with feeding large amounts of concentrates and less forage is that concentrates are processed in a different manner than forage. Concentrates are digested in the stomach and small intestine; the biproducts produced are volatile fatty acids, alcohol, and lactic acid. A LOT of acids. More concentrates ALSO can impact the active microbiome.

The lower half of the stomach produces a protective mucous, bicarbonate, HCl (stomach acid) and pepsinogen (which aids in breakdown of proteins). The ulcers that manifest in the lower half are typically due to excess cortisol (stress) or NSAIDs.

What actually causes ulcers?

Some horses are naturally more prone to ulcers but for many it’s entirely the environment.

Exercise: As with humans, horses tighten their core during exercise. Exercise can increase stomach pressure and decrease stomach volume making it easier for stomach acid to contact the proximal half.

Mealtimes: Modern horse keeping usually only had horses being fed twice a day. I have seen many horses standing around waiting for their next meal for hours. Whether or not a horse is being fed the horse continues to produce stomach acid all day long; remember the visual? In one day a horse can produce 9-10 gallons of stomach acid! If a horse isn’t chewing, however, it is not producing saliva. Saliva is one of the best ways to buffer stomach acid because it contains buffering agents. The pH of a horse’s stomach is said to drop about 6 hours after feeding. Having two meals each day can leave them with a lot of time without saliva production.

Diet: Studies have shown that a diet with higher protein and calcium (alfalfa) can help increase the pH of the gut and the horses had less severe ulcers. Similarly more ulcers were found in horses on a mixed feed (commercial feed) diet versus hay.

Stress: Stresses such as transportation and stalls are said to have a stressful element that increases cortisol and stomach acid. This information can be highly varied, however, since all horses have different stress tolerances and preferences. A horse that rarely goes off property would be far more stressed than a horse that travels regularly. Length of transportation and the driver would also be important elements.

Pharmaceuticals: NSAIDS such as Bute, Equioxx, and Banamine can be damaging to the GI system, particularly to the lower half of the stomach. These drugs work to block prostaglandin. In a chain of reactions the mucosal blood flow decreases which reduces mucous production and increases acid production. Prolonged use of these drugs can be damaging so take care when administering.

Considering all of the causes that can lead to ulcers it becomes more obvious why so many horses are plagued with the condition. It really is no wonder why 90% of racehorses experience ulcers. Let’s consider them for a moment:

Racehorses are stalled most of the day with little to no access to any turnout. They are often trailered from track to track for different races. Racehorses require a lot more feed than the average horse because of their physical demands. and are often fed large meals of grains or concentrates. They have access to hay but a large part of their diet is hydrolyzable carbohydrates. These athletes have intense fitness programs. Essentially racehorses have the perfect setting to ensure ulcer formation.

That doesn’t mean your trail horse won’t get ulcers. Unfortunately ulcers cannot be ruled out just because of a relaxed environment.

In future posts I am going to share how you can prevent ulcers. I’ll also share how I handle ulcers at home as well as some other options for you to explore if you suspect trouble in your horse so stay tuned!


  • Andrews FM, Sifferman RL, Bernard W, Hughes FE, Holste JE, Daurio CP, Alva R, Cox JL. Efficacy of omeprazole paste in the treatment and prevention of gastric ulcers in horses. Equine Vet J Suppl. 1999 Apr;(29):81-6. doi: 10.1111/j.2042-3306.1999.tb05176.x. PMID: 10696301.
  • Woodward, Michelle & Huff, Nan & Garza, Frank & Keowen, Michael & Kearney, Michael & Andrews, Frank. (2014). Effect of pectin, lecithin, and antacid feed supplements (Egusin®) on gastric ulcer scores, gastric fluid pH and blood gas values in horses. BMC veterinary research. 10. S4. 10.1186/1746-6148-10-S1-S4.
  • F. M. Andrews, B. R. Buchanan, S. B. Elliot, N. A. Clariday, L. H. Edwards, Gastric ulcers in horses, Journal of Animal Science, Volume 83, Issue suppl_13, June 2005, Pages E18–E21,
  • Wolford AN, Coverdale JA, Leatherwood JL, Pinchak WE, Anderson RC, Wickersham TA. Influence of housing type on the cecal environment of horses. Transl Anim Sci. 2019 Apr 24;3(2):877-884. doi: 10.1093/tas/txz030. PMID: 32704852; PMCID: PMC7200855.

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