09/25/2026
Ulcers are a common topic, and unfortunately a common pain horses experience! Some ways to prevent them are listed out in the post. And, if you suspect your horse may have ulcers contact your vet as they can give you the most accurate plan of action to help your specific horse heal.
𝐑𝐞𝐬𝐞𝐚𝐫𝐜𝐡 𝐁𝐞𝐡𝐢𝐧𝐝 𝐄𝐪𝐮𝐢𝐧𝐞 𝐆𝐚𝐬𝐭𝐫𝐢𝐜 𝐔𝐥𝐜𝐞𝐫 𝐒𝐲𝐧𝐝𝐫𝐨𝐦𝐞 (𝐄𝐆𝐔𝐒)
I was inspired to write this post while preparing a talk I’ll be giving to University of Minnesota veterinary students next week. The presentation is largely inspired by a presentation from Dr. Ben Sykes, which I’ll 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:
𝐄𝐪𝐮𝐢𝐧𝐞 𝐬𝐪𝐮𝐚𝐦𝐨𝐮𝐬 𝐠𝐚𝐬𝐭𝐫𝐢𝐜 𝐝𝐢𝐬𝐞𝐚𝐬𝐞 (𝐄𝐒𝐆𝐃) is analogous to heartburn in humans. These ulcers occur on the upper third of the stomach due to prolonged exposure to stomach acid.
𝐄𝐪𝐮𝐢𝐧𝐞 𝐠𝐥𝐚𝐧𝐝𝐮𝐥𝐚𝐫 𝐠𝐚𝐬𝐭𝐫𝐢𝐜 𝐝𝐢𝐬𝐞𝐚𝐬𝐞 (𝐄𝐆𝐆𝐃) 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:
𝐃𝐞𝐭𝐞𝐫𝐦𝐢𝐧𝐞 𝐡𝐨𝐰 𝐦𝐮𝐜𝐡 𝐡𝐚𝐲 𝐭𝐡𝐞 𝐡𝐨𝐫𝐬𝐞 𝐢𝐬 𝐚𝐜𝐭𝐮𝐚𝐥𝐥𝐲 𝐞𝐚𝐭𝐢𝐧𝐠. Just because they have free-choice access to forage doesn’t 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:
🥕 𝐔𝐬𝐞 𝐬𝐥𝐨𝐰-𝐟𝐞𝐞𝐝 𝐡𝐚𝐲 𝐧𝐞𝐭𝐬. A study found that using a slow-feed hay net (1¼”) 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 (6”) holes (Glunk et al., 2014).
🥕 𝐅𝐞𝐞𝐝 𝟑+ 𝐦𝐞𝐚𝐥𝐬 𝐩𝐞𝐫 𝐝𝐚𝐲. 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.
🥕 𝐀𝐝𝐝 𝐮𝐩 𝐭𝐨 𝟓𝟎% 𝐬𝐭𝐫𝐚𝐰 𝐢𝐧𝐭𝐨 𝐭𝐡𝐞 𝐝𝐢𝐞𝐭. 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:
𝐔𝐬𝐞 𝐚 𝐜𝐨𝐦𝐦𝐞𝐫𝐜𝐢𝐚𝐥 𝐛𝐮𝐟𝐟𝐞𝐫. 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.
𝐔𝐭𝐢𝐥𝐢𝐳𝐞 𝐦𝐮𝐥𝐭𝐢𝐩𝐥𝐞 𝐡𝐚𝐲 𝐧𝐞𝐭𝐬 𝐢𝐧 𝐚 𝐬𝐭𝐚𝐥𝐥. 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.
𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐢𝐜𝐚𝐥𝐥𝐲 𝐞𝐱𝐞𝐫𝐜𝐢𝐬𝐞 𝐲𝐨𝐮𝐫 𝐡𝐨𝐫𝐬𝐞. 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.
𝐋𝐢𝐦𝐢𝐭 𝐰𝐨𝐫𝐤𝐢𝐧𝐠 𝐚 𝐡𝐨𝐫𝐬𝐞 𝐚𝐛𝐨𝐯𝐞 𝐭𝐡𝐞 𝐭𝐫𝐨𝐭 𝐭𝐨 𝐥𝐞𝐬𝐬 𝐭𝐡𝐚𝐧 𝟑𝟎–𝟒𝟎 𝐦𝐢𝐧𝐮𝐭𝐞𝐬. 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 30–40 minutes may help mitigate these concerns. And once again, feeding a meal or using a gastric buffer prior to exercise can help as well.
𝐅𝐞𝐞𝐝 𝐥𝐞𝐬𝐬 𝐭𝐡𝐚𝐧 𝟏 𝐠 𝐬𝐭𝐚𝐫𝐜𝐡 𝐩𝐞𝐫 𝐤𝐠 𝐛𝐨𝐝𝐲𝐰𝐞𝐢𝐠𝐡𝐭 𝐩𝐞𝐫 𝐦𝐞𝐚𝐥. 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.
𝐄𝐪𝐮𝐢𝐧𝐞 𝐆𝐥𝐚𝐧𝐝𝐮𝐥𝐚𝐫 𝐆𝐚𝐬𝐭𝐫𝐢𝐜 𝐃𝐢𝐬𝐞𝐚𝐬𝐞
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 𝐢𝐧𝐯𝐞𝐬𝐭𝐢𝐠𝐚𝐭𝐞 𝐚𝐧𝐲 𝐜𝐨𝐧𝐟𝐨𝐮𝐧𝐝𝐢𝐧𝐠 𝐟𝐚𝐜𝐭𝐨𝐫𝐬 that may be associated with pain. Some examples include saddle fit, lameness, or dental problems.
How we house our horses is also important.
𝐀𝐥𝐥𝐨𝐰 𝐡𝐨𝐫𝐬𝐞𝐬 𝐭𝐡𝐞 𝐨𝐩𝐩𝐨𝐫𝐭𝐮𝐧𝐢𝐭𝐲 𝐭𝐨 𝐚𝐜𝐭𝐢𝐯𝐞𝐥𝐲 𝐞𝐧𝐠𝐚𝐠𝐞 𝐢𝐧 𝐬𝐨𝐜𝐢𝐚𝐥 𝐛𝐞𝐡𝐚𝐯𝐢𝐨𝐫𝐬, 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).
𝐅𝐫𝐢𝐞𝐧𝐝𝐬, 𝐟𝐨𝐫𝐚𝐠𝐞, 𝐚𝐧𝐝 𝐟𝐫𝐞𝐞𝐝𝐨𝐦 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).
𝐌𝐚𝐬𝐬𝐚𝐠𝐞 𝐚𝐧𝐝 𝐜𝐥𝐚𝐬𝐬𝐢𝐜𝐚𝐥 𝐦𝐮𝐬𝐢𝐜 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 (Kędzierski et al., 2017).
𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧𝐬
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
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Jansson A, Harris P, Davey SL, Luthersson N, Ragnarsson S, Ringmark S. Straw as an alternative to grass forage in horses—effects 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.
Kędzierski 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.
