Gastric Ulcers? Consider Antioxidant Support for Your Horse

Researchers found horses with EGUS are under greater oxidative stress and concluded they might benefit from additional antioxidant therapy.

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Gastric Ulcers? Consider Antioxidant Support for Your Horse
Researchers concluded that horses with EGUS might benefit from additional antioxidant therapy. Common antioxidants in the equine diet include vitamin E, selenium, and vitamin C. | Photo: The Horse Staff

Q. My horse was recently scoped and diagnosed with gastric ulcers and is being treated for them. I have him on a gastric support supplement in hopes it will help reduce the risk of the ulcers recurring once the prescribed medication ends. Other than making the management changes that are often recommended for horses with a history of ulcers, is there anything else I could be doing to help him recover?

A. Gastric ulcers are a common and sometimes persistent issue in horses. While they most often occur in performance horses, they also affect horses at pasture, those not being worked, and those displaying no clinical signs. Several supplements on the market have shown promise under research conditions in reducing the number and severity of gastric ulcers. Using one of these products long-term might help reduce the risk of ulcer recurrence. As you state, management changes are often necessary and hopefully will minimize or remove stressors that might have been triggering ulcer development.

Researchers recently investigated specific and nonspecific biomarkers that could be used to diagnose equine gastric ulcer syndrome (EGUS), according to a study published in the January 2020 edition of the Journal of Equine Veterinary Science. Their goals were to find markers that could be assessed in blood samples that would indicate whether a horse did or did not have ulcers. This premise was based on human research that showed doctors could use serum pepsinogen and gastrin as diagnostic markers for the indirect assessment of gastritis. However, in this equine study, serum pepsinogen and gastrin showed no significant changes in horses with EGUS versus those that were healthy.

When the researchers looked at other potential markers, they found some interesting things. Proinflammatory cytokines, which are major contributors to tissue damage, were elevated in horses with EGUS. They also found horses with EGUS had significantly lower levels of nitric oxide (NO). NO is considered to be a gastroprotective compound because it controls the release of hydrochloric acid and works as an antioxidant against tissue-damaging free radicals.

While the researchers didn’t find any clear markers useful for diagnostic purposes, they did show horses with EGUS are under greater oxidative stress. They concluded that horses with EGUS might benefit from additional antioxidant therapy. Common antioxidants in the equine diet include vitamin E, selenium, and vitamin C.

Vitamin E is often low in horses without access to good-quality, fresh pasture most of the day. Dietary selenium might also be low depending on your geographic location and what additional sources you provide. Horses manufacture their own vitamin C, but in some instances they benefit from additional supplementation.

Based on this research you might wish to evaluate your horse’s antioxidant status and see whether you can offer additional support during the healing process. I recommend you work with your veterinarian to assess your horse’s vitamin E and selenium status via bloodwork, and then supplement as necessary based on the results. A qualified nutritionist can help you to assess the overall diet to make sure your horse’s needs are being met. If you decide to supplement vitamin C, look for the ester-C form, as it’s a little gentler on the stomach. Keep in mind that supplementing vitamin C might result in the horse producing less of his own, and if you stop supplementing in the future, you will need to do so slowly to allow endogenous levels to reestablish.


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Written by:

Clair Thunes, PhD, is an equine nutritionist who owns Clarity Equine Nutrition, based in Gilbert, Arizona. She works as a consultant with owners/trainers and veterinarians across the United States and globally to take the guesswork out of feeding horses and provides services to select companies. As a nutritionist she works with all equids, from WEG competitors to Miniature donkeys and everything in between. Born in England, she earned her undergraduate degree at Edinburgh University, in Scotland, and her master’s and doctorate in nutrition at the University of California, Davis. Growing up, she competed in a wide array of disciplines and was an active member of the U.K. Pony Club. Today, she serves as the district commissioner for the Salt River Pony Club.

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