09/26/2026
๐๐๐ฌ๐๐๐ซ๐๐ก ๐๐๐ก๐ข๐ง๐ ๐๐ช๐ฎ๐ข๐ง๐ ๐๐๐ฌ๐ญ๐ซ๐ข๐ ๐๐ฅ๐๐๐ซ ๐๐ฒ๐ง๐๐ซ๐จ๐ฆ๐ (๐๐๐๐)
I was inspired to write this post while preparing a talk Iโll be giving to University of Minnesota veterinary students next week. The presentation is largely inspired by a presentation from Dr. Ben Sykes, which Iโll link in the comments for anyone interested in learning more.
Equine gastric ulcer syndrome involves sores or lesions on the lining of the stomach, often caused by irritation from stomach acid or digestive enzymes.
There are two distinct forms of ulcers that are diagnosed based on the tissue in which they are found:
๐๐ช๐ฎ๐ข๐ง๐ ๐ฌ๐ช๐ฎ๐๐ฆ๐จ๐ฎ๐ฌ ๐ ๐๐ฌ๐ญ๐ซ๐ข๐ ๐๐ข๐ฌ๐๐๐ฌ๐ (๐๐๐๐) is analogous to heartburn in humans. These ulcers occur on the upper third of the stomach due to prolonged exposure to stomach acid.
๐๐ช๐ฎ๐ข๐ง๐ ๐ ๐ฅ๐๐ง๐๐ฎ๐ฅ๐๐ซ ๐ ๐๐ฌ๐ญ๐ซ๐ข๐ ๐๐ข๐ฌ๐๐๐ฌ๐ (๐๐๐๐) is a complex, inflammatory condition involving lesions on the lower region of the stomach. This condition is associated with stress levels in the horse.
While omeprazole is the only medication approved to treat EGUS in horses, feed and management strategies exist to reduce the risk of occurrence. Here are some recommendations based on research:
๐๐๐ญ๐๐ซ๐ฆ๐ข๐ง๐ ๐ก๐จ๐ฐ ๐ฆ๐ฎ๐๐ก ๐ก๐๐ฒ ๐ญ๐ก๐ ๐ก๐จ๐ซ๐ฌ๐ ๐ข๐ฌ ๐๐๐ญ๐ฎ๐๐ฅ๐ฅ๐ฒ ๐๐๐ญ๐ข๐ง๐ . Just because they have free-choice access to forage doesnโt mean they are eating enough. Some reasons include poor-quality forage that reduces palatability, herd dynamics, stress, or miscalculations on the amount of forage provided. In an ideal situation, we can provide continuous access to forage while maintaining the horse at a healthy weight.
Unfortunately, this is not always possible, particularly for horses who need to manage their weight. Thankfully, there are a few strategies we can use to encourage frequent consumption while limiting calories or reducing intake:
๐ฅ ๐๐ฌ๐ ๐ฌ๐ฅ๐จ๐ฐ-๐๐๐๐ ๐ก๐๐ฒ ๐ง๐๐ญ๐ฌ. A study found that using a slow-feed hay net (1ยผโ) can double the amount of time it takes to consume a meal compared to horses who are fed without a hay net or from a hay net with large (6โ) holes (Glunk et al., 2014).
๐ฅ ๐
๐๐๐ ๐+ ๐ฆ๐๐๐ฅ๐ฌ ๐ฉ๐๐ซ ๐๐๐ฒ. The same study found that horses fed 2% BW divided into two meals per day finished each meal in 6.5 hours on average. This means horses had 5.5 hours of fasting between meals on average. Dividing these feedings into 3 meals can help reduce each fasting window.
๐ฅ ๐๐๐ ๐ฎ๐ฉ ๐ญ๐จ ๐๐% ๐ฌ๐ญ๐ซ๐๐ฐ ๐ข๐ง๐ญ๐จ ๐ญ๐ก๐ ๐๐ข๐๐ญ. Straw, or a lower-quality hay, can be used as a filler for the horse. These forages can provide a buffer while limiting extra calories. A study evaluating the addition of 50% wheat straw alongside grass silage found that horses fed 50% straw took longer to eat and had lower ulcer scores compared to the control group fed silage only (Jansson et al., 2021).
While these practices are useful for horses who require limited forage availability, there are also many recommendations that can benefit any horse, including:
๐๐ฌ๐ ๐ ๐๐จ๐ฆ๐ฆ๐๐ซ๐๐ข๐๐ฅ ๐๐ฎ๐๐๐๐ซ. Purina conducted research on a seaweed-derived calcium buffer (Outlast) added to a meal and found benefits for buffering the pH of the stomach (Jacobs et al., 2020). I personally recommend using these supplements prior to times when a horse might be without feed or choose to fast, such as immediately before exercising, hauling, at shows, or at night check.
๐๐ญ๐ข๐ฅ๐ข๐ณ๐ ๐ฆ๐ฎ๐ฅ๐ญ๐ข๐ฉ๐ฅ๐ ๐ก๐๐ฒ ๐ง๐๐ญ๐ฌ ๐ข๐ง ๐ ๐ฌ๐ญ๐๐ฅ๐ฅ. Horses naturally fast at night, however, we would like to reduce this fasting window to lower the risk of ulcers. A study found that dividing hay into multiple, double-netted hay nets prolonged the time spent eating overnight without sacrificing the resting period compared to when a single hay net was provided (Ellis et al., 2015). These hay nets should be placed in different locations throughout the stall to encourage movement and increase opportunities to eat.
๐๐ญ๐ซ๐๐ญ๐๐ ๐ข๐๐๐ฅ๐ฅ๐ฒ ๐๐ฑ๐๐ซ๐๐ข๐ฌ๐ ๐ฒ๐จ๐ฎ๐ซ ๐ก๐จ๐ซ๐ฌ๐. Since horses naturally fast overnight, exercising first thing in the morning can increase the risk of ulcer development. As a result, it is important to break the fast before you ride. This can be done by providing forage or a commercial buffer to reduce acid exposure to the squamous region of the stomach.
๐๐ข๐ฆ๐ข๐ญ ๐ฐ๐จ๐ซ๐ค๐ข๐ง๐ ๐ ๐ก๐จ๐ซ๐ฌ๐ ๐๐๐จ๐ฏ๐ ๐ญ๐ก๐ ๐ญ๐ซ๐จ๐ญ ๐ญ๐จ ๐ฅ๐๐ฌ๐ฌ ๐ญ๐ก๐๐ง ๐๐โ๐๐ ๐ฆ๐ข๐ง๐ฎ๐ญ๐๐ฌ. Another study found that stomach pH drops during exercise and gradually returns to baseline once exercise stops (Lorenzo-Figueras and Merritt, 2002). Since the risk of ulcers increases with prolonged exposure to stomach acid, limiting exercise above the trot to less than 30โ40 minutes may help mitigate these concerns. And once again, feeding a meal or using a gastric buffer prior to exercise can help as well.
๐
๐๐๐ ๐ฅ๐๐ฌ๐ฌ ๐ญ๐ก๐๐ง ๐ ๐ ๐ฌ๐ญ๐๐ซ๐๐ก ๐ฉ๐๐ซ ๐ค๐ ๐๐จ๐๐ฒ๐ฐ๐๐ข๐ ๐ก๐ญ ๐ฉ๐๐ซ ๐ฆ๐๐๐ฅ. The type of meal fed is important, as feeds high in starch and sugar (greater than 1 g starch/kg BW/meal) were associated with a 2.6 times increased likelihood of developing EGUS (Luthersson et al., 2009). This means the average 500 kg (1,100-lb) horse should not receive more than 500 g of starch per meal. For a textured feed with 33% starch, this means the horse should not receive more than 3.3 lbs per meal. Meanwhile, a pelleted feed that contains 10% starch does not hit this threshold until 11 lbs per meal are fed, which exceeds the maximum 5 lbs per meal limit recommended to avoid digestive overload.
๐๐ช๐ฎ๐ข๐ง๐ ๐๐ฅ๐๐ง๐๐ฎ๐ฅ๐๐ซ ๐๐๐ฌ๐ญ๐ซ๐ข๐ ๐๐ข๐ฌ๐๐๐ฌ๐
When looking at EGGD, our main focus is to reduce stress in the horse. This can be done by managing their living situation and exercise regimen.
The first step is to ๐ข๐ง๐ฏ๐๐ฌ๐ญ๐ข๐ ๐๐ญ๐ ๐๐ง๐ฒ ๐๐จ๐ง๐๐จ๐ฎ๐ง๐๐ข๐ง๐ ๐๐๐๐ญ๐จ๐ซ๐ฌ that may be associated with pain. Some examples include saddle fit, lameness, or dental problems.
How we house our horses is also important.
๐๐ฅ๐ฅ๐จ๐ฐ ๐ก๐จ๐ซ๐ฌ๐๐ฌ ๐ญ๐ก๐ ๐จ๐ฉ๐ฉ๐จ๐ซ๐ญ๐ฎ๐ง๐ข๐ญ๐ฒ ๐ญ๐จ ๐๐๐ญ๐ข๐ฏ๐๐ฅ๐ฒ ๐๐ง๐ ๐๐ ๐ ๐ข๐ง ๐ฌ๐จ๐๐ข๐๐ฅ ๐๐๐ก๐๐ฏ๐ข๐จ๐ซ๐ฌ, even when stalled. A study found that horses housed in a half stall where they could engage with another horse neck-to-neck displayed more relaxed behaviors, while those housed with a wall between them displayed more alert behaviors (Borthwick et al., 2023).
๐
๐ซ๐ข๐๐ง๐๐ฌ, ๐๐จ๐ซ๐๐ ๐, ๐๐ง๐ ๐๐ซ๐๐๐๐จ๐ฆ can also reduce stress and subsequent risks of health problems. In a survey conducted in the UK and Ireland, horses with 24-hour access to turnout with friends were less likely to exhibit gastrointestinal issues, lameness issues, handling problems, or antisocial behaviors compared to two other groups with more restrictive management systems, including stalling and isolation (Watson et al., 2026).
๐๐๐ฌ๐ฌ๐๐ ๐ ๐๐ง๐ ๐๐ฅ๐๐ฌ๐ฌ๐ข๐๐๐ฅ ๐ฆ๐ฎ๐ฌ๐ข๐ may also help lower stress in horses. One study found that massage and classical music not only improved relaxation in Arabian racehorses, but massage also improved their performance on the track (Kฤdzierski et al., 2017).
๐๐จ๐ง๐๐ฅ๐ฎ๐ฌ๐ข๐จ๐ง๐ฌ
Gastric ulcers are a common concern in horses, particularly those exposed to the management and exercise factors that increase their risk. While we cannot eliminate every risk factor, research gives us several practical tools to support gastric health.
If we are waiting to treat ulcers, we have waited too long. Rather, we need to look at the horse's entire management program and identify opportunities to reduce prolonged fasting, excessive starch intake, stomach acid exposure, and stress. Small changes in how we feed, house, exercise, and manage our horses can help reduce risk and support better overall digestive health.
Cheers,
Dr. DeBoer
Glunk ME, Hathaway PM, Weber MW, Sheaffer PC, Martinson PK. The effect of hay net design on rate of forage consumption when feeding adult horses. Journal of Equine Veterinary Science. 2014 Aug 1;34(8):986-91.
Jansson A, Harris P, Davey SL, Luthersson N, Ragnarsson S, Ringmark S. Straw as an alternative to grass forage in horsesโeffects on post-prandial metabolic profile, energy intake, behaviour and gastric ulceration. Animals. 2021 Jul 24;11(8):2197.
Ellis AD, Redgate S, Zinchenko S, Owen H, Barfoot C, Harris P. The effect of presenting forage in multi-layered haynets and at multiple sites on night time budgets of stabled horses. Applied Animal Behaviour Science. 2015 Oct 1;171:108-16.
Jacobs RD, Gordon MB, Vineyard KR, Keowen ML, Garza Jr F, Andrews FM. The effect of a seaweed-derived calcium supplement on gastric juice pH in the horse. Journal of equine veterinary science. 2020 Dec 1;95:103265.
Lorenzo-Figueras M, Merritt AM. Effects of exercise on gastric volume and pH in the proximal portion of the stomach of horses. American Journal of Veterinary Research. 2002 Nov 1;63(11):1481-7.
Luthersson N, Nielsen KH, Harris P, Parkin TD. Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark. Equine veterinary journal. 2009 Sep;41(7):625-30.
Borthwick EJ, Preshaw L, Wheeler-Launder C, Challinor C, Housby-Skeggs N, Boalch E, Brown SM, Pearson G. Stable design influences relaxation and affiliative behavior in horses during short isolation bouts. Journal of Veterinary Behavior. 2023 Nov 1;69:1-7.
Watson W, MacKay JR, Dwyer C. Friends, forage, freedom: A cluster analysis investigating horse management styles and welfare in the UK and Ireland. Animal Welfare. 2026 Jan;35:e15.
Kฤdzierski W, Janczarek I, Stachurska A, Wilk I. Massage or music meant to be relaxing, result in lowering salivary cortisol concentration in race horses. Pferdeheilkunde. 2017 Mar 1;33(2):146.
