# Equine Gastric Ulcer Syndrome EGUS: Gastrogard Omeprazole Treatment ## Key Takeaways - Equine Gastric Ulcer Syndrome (EGUS) is an umbrella term for Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD), differing in location, pathophysiology, and treatment response. Gastroscopy is the definitive diagnostic method for both entities. - Omeprazole, a proton pump inhibitor, is the primary medical therapy, particularly for ESGD, by irreversibly blocking gastric acid secretion. Gastrogard is the veterinary-approved oral omeprazole paste formulation. - Standard treatment for EGUS involves oral omeprazole at 4 mg/kg once daily for a minimum of 28 days, with longer durations (up to 6 weeks) often required for EGGD. Administration on an empty stomach, 30 minutes prior to feeding, maximizes absorption. - High prevalence of EGUS (up to 93% in racehorses) is linked to intensive training, intermittent feeding, high-concentrate diets, stress, and NSAID use. Recurrence is common, with even short omeprazole withholding periods impacting susceptible horses. - While omeprazole is effective, EGGD response can be variable, sometimes necessitating combination therapy with sucralfate. Emerging non-invasive salivary biomarkers (e.g., bicarbonate, urea, trace elements, calprotectin) show promise for monitoring treatment but are not yet routine diagnostics. - Management requires a multi-modal approach including dietary modifications (maximize forage, minimize grain meals), stress reduction, and potentially behavioral medicine for chronic cases. Human omeprazole formulations are not bioavailable or appropriately dosed for horses. --- Equine Gastric Ulcer Syndrome (EGUS) is one of the most common and significant diseases affecting the equine stomach, with a high prevalence in performance and racing disciplines [1][2]. This condition is an umbrella term that encompasses two distinct diseases: Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD) [2]. These entities differ in their pathophysiology, risk factors, and response to treatment, making accurate diagnosis and targeted therapy essential [3][2]. For owners and trainers, the primary medical therapy for EGUS is the administration of omeprazole, a proton pump inhibitor. The most recognized veterinary formulation is Gastrogard (oral omeprazole paste). This article provides a definitive, source-grounded overview of EGUS, with a specific focus on the use of Gastrogard (omeprazole) for treatment, supported by current scientific literature and clinical guidelines. **Owner Triage Summary:** If your horse is showing signs such as poor appetite, weight loss, decreased performance, girth aversion, or recurrent colic, EGUS should be a primary differential. While you await veterinary consultation, ensure constant access to forage, reduce grain intake, and minimize stressors. Do not administer human omeprazole formulations without veterinary guidance, as dosing and bioavailability differ significantly. **Gastroscopy is the only definitive method for diagnosing EGUS and is essential before starting treatment.** Contact your veterinarian to schedule an endoscopic examination. ## At a Glance: EGUS and Omeprazole Treatment | Feature | Equine Squamous Gastric Disease (ESGD) | Equine Glandular Gastric Disease (EGGD) | | :--- | :--- | :--- | | **Location** | Non-glandular (squamous) mucosa, proximal stomach | Glandular mucosa, distal stomach | | **Primary Cause** | Acid splash and exposure to volatile fatty acids [2] | Multi-factorial, often linked to stress, inflammation, and NSAID use [4][2] | | **Primary Treatment** | Omeprazole (Gastrogard) [5][2] | Omeprazole, often combined with sucralfate or other therapies [2][6] | | **Response to Omeprazole** | Generally excellent, with high healing rates [5][2] | Variable; often requires longer treatment and additional management [1][2] | | **Diagnosis** | Gastroscopy with visual scoring [2][7] | Gastroscopy with visual scoring [2][7] | | **Key Management** | Maximize forage intake, reduce concentrate meals, manage training schedules [2][8] | Address stress, reduce NSAID use, consider behavioral modification [4][3][2] | ## Understanding Equine Gastric Ulcer Syndrome (EGUS) EGUS is a term used since 1999 to describe gastric mucosal disease in horses [2]. However, it is now recognized that EGUS encompasses two separate conditions with different etiologies and treatment strategies: ESGD and EGGD [2]. The European College of Equine Internal Medicine (ECEIM) released a consensus statement in 2015 that formally defined these entities and highlighted the evidence gaps, particularly concerning EGGD [2]. The prevalence of EGUS is alarmingly high. Studies show that up to 93% of racehorses can be affected [1]. In a study of 395 horses in China, the overall prevalence of gastric ulcers was 78% [7]. This high prevalence underscores the importance of understanding the risk factors and implementing effective prevention and treatment protocols [7]. ### The Two Diseases: ESGD vs. EGGD **Equine Squamous Gastric Disease (ESGD)** affects the squamous mucosa, the tissue lining the upper portion of the stomach. This region has no protective mucus layer and is constantly exposed to gastric acid. ESGD is primarily caused by acid splash, which occurs when the stomach is empty or when intra-abdominal pressure increases during exercise, forcing acid into the squamous region [2]. Management focuses on reducing acid exposure by providing frequent forage and limiting fasting periods [2]. **Equine Glandular Gastric Disease (EGGD)** affects the glandular mucosa, the lower portion of the stomach that produces acid and digestive enzymes. Unlike ESGD, EGGD is not solely an acid-related disease. It is more closely associated with inflammation, immune system dysfunction, and stress [4][9][2]. The pathophysiology is complex and involves a breakdown in the mucosal barrier, often triggered by psychological stress, high-intensity training, and the use of non-steroidal anti-inflammatory drugs (NSAIDs) like flunixin meglumine [4][2]. Treatment for EGGD often requires a multi-modal approach that goes beyond simple acid suppression [3][2]. ## The Role of Omeprazole in Treating EGUS Omeprazole is a proton pump inhibitor (PPI) that works by irreversibly binding to the H+/K+-ATPase enzyme in the parietal cells of the stomach, effectively blocking the final step of acid secretion. This profound and long-lasting reduction in gastric acidity creates an environment that allows existing ulcers to heal and prevents the formation of new ones. It is the cornerstone of medical therapy for EGUS, particularly for ESGD [5][2]. ### Gastrogard: The Veterinary Formulation Gastrogard is the trade name for the oral omeprazole paste specifically formulated and approved for use in horses. The efficacy and safety of oral omeprazole in treating EGUS is well-documented in the scientific literature [5][2]. While generic omeprazole products exist, the formulation, bioavailability, and buffering system can vary. Studies have compared different formulations of oral omeprazole to assess their efficacy in treating naturally occurring ulcers in racehorses [5]. One study compared a powder paste with gastro-enteric resistant granules. Both formulations were found to be effective in treating gastric ulcers, with significant improvements in ulcer scores after 28 days of treatment [5]. However, the choice of formulation may depend on factors such as palatability, ease of administration, and cost, and should be discussed with a veterinarian [5]. The key is to use a product with proven bioavailability and efficacy, and Gastrogard has a long track record of clinical success. ### Evidence for Omeprazole Efficacy The scientific evidence supporting omeprazole's efficacy in treating ESGD is robust. A blinded, randomized clinical trial involving racehorses demonstrated significant improvements in gastric ulcer scores after 28 days of treatment with oral omeprazole [5]. The study found no significant differences in efficacy between the two tested formulations, confirming that consistent, daily administration of an effective oral omeprazole product is key to successful treatment [5]. However, the response to omeprazole is not always uniform, particularly for EGGD. A pilot study investigating changes in saliva analytes after EGUS treatment found that only 15 out of 28 horses (approximately 54%) had a successful treatment outcome after six weeks of omeprazole therapy [1]. This highlights that while omeprazole is the first-line treatment, it is not a universal cure, especially for glandular disease, and additional therapies or management changes may be necessary [1][2]. ## Gastrogard (Omeprazole) Treatment Protocols The standard recommended treatment for EGUS is oral omeprazole at a dose of 4 mg/kg once daily for at least 28 days [4][5]. The duration of treatment is critical, as it allows sufficient time for the gastric mucosa to heal. In many cases, particularly with EGGD, a longer course of treatment (up to 6 weeks or more) may be required [1][2]. ### Standard Dosing and Administration - **Dose:** 4 mg/kg of body weight, administered orally once daily [4][5]. - **Duration:** Minimum of 28 days. For EGGD, a 6-week course is often recommended [1][2]. - **Administration:** Gastrogard is typically administered as a paste directly into the horse's mouth. For best results, it should be given on an empty stomach, ideally 30 minutes before feeding, to maximize absorption and efficacy. ### The Role of "Withholding Periods" and Recurrence A significant challenge in managing EGUS is the high rate of recurrence after treatment is stopped. The concept of a "withholding period" (RWP) is common in racing jurisdictions, where medication must be withdrawn before a race. A study investigated the impact of two common RWPs for omeprazole on the recurrence of EGUS in Thoroughbred racehorses [10]. The study compared a "2-clear-days" RWP (meaning the last dose was given 2 days before the race) with a "not on race-day" RWP (meaning the horse could receive medication up until the day before the race). The results were striking. More horses were affected by ESGD after the "2-clear-days" RWP than after the "not on race-day" RWP [10]. This suggests that even a short period without omeprazole can be sufficient for ulcers to recur in susceptible horses. This finding has significant welfare implications and suggests that the timing of omeprazole withdrawal should be carefully considered in performance horses [10]. The study also explored the use of a nutraceutical supplement during the RWP and found that it reduced the prevalence of ESGD post-RWP compared to the starting point, although it did not eliminate the risk entirely [10]. ### Combination Therapy: Omeprazole and Sucralfate For more severe cases, particularly those involving EGGD, a combination of omeprazole and sucralfate is often used. Sucralfate is a cytoprotective agent that forms a protective barrier over the ulcerated mucosa and promotes healing. A study on heart rate variability in horses with EGUS treated them with a combination of omeprazole and sucralfate for 28 days [6]. While the study did not find significant changes in HRV indices, it confirmed that this combination is a standard and safe treatment protocol for ESGD [6]. ### Addressing NSAID-Induced Ulcers The use of NSAIDs, such as flunixin meglumine (FM), is common for managing pain and inflammation in horses. However, NSAIDs are a known risk factor for EGUS, particularly for glandular ulcers [4]. A study investigated the co-administration of omeprazole and FM in Mongolian horses with chronic lameness [4]. The study aimed to determine if omeprazole could mitigate the ulcerogenic effects of FM. The results suggested that the combination of FM and omeprazole was safe and did not worsen EGUS scores compared to FM alone, indicating a potential protective effect of omeprazole in horses requiring NSAID therapy [4]. This is a crucial consideration for veterinarians when developing pain management plans for horses with conditions like lameness. ## Diagnostics: Confirming EGUS and Monitoring Treatment A definitive diagnosis of EGUS can only be made via gastroscopy, which involves passing an endoscope into the horse's stomach to visually inspect the mucosa [11][2][7]. This procedure allows the veterinarian to grade the severity of lesions in both the squamous and glandular regions [2][7]. ### The Importance of Gastroscopy Gastroscopy is not only essential for diagnosis but also for monitoring the response to treatment. A follow-up gastroscopy after the treatment period is the gold standard for confirming ulcer healing and determining if further therapy is needed [1][11]. Without this, treatment decisions are often made blindly, which can lead to unnecessary medication or premature cessation of therapy. ### Emerging Non-Invasive Biomarkers Given the cost and invasiveness of gastroscopy, there is significant interest in developing non-invasive biomarkers for EGUS. Recent research has focused on analyzing saliva and serum for various analytes that may change with the presence of ulcers and their response to treatment. - **Salivary Analytes:** Studies have shown that horses with EGUS have changes in salivary levels of various biomarkers, including: - **Bicarbonate and Urea:** Horses with successful treatment showed significant increases in these analytes [1]. - **Adenosine Deaminase (ADA) and Creatine Kinase (CK):** These decreased significantly in horses with successful treatment [1]. - **Trace Elements:** Horses with EGGD had significantly lower levels of Zinc and Magnesium in their saliva, while Iron was lower in horses with both ESGD and EGGD [12]. - **Ammonia and Bicarbonate:** EGUS is associated with higher salivary ammonia and lower bicarbonate [13]. - **Immunoglobulins:** Salivary IgA was significantly increased in horses with EGUS, indicating immune system involvement [9]. - **Calprotectin:** Salivary calprotectin (S100A8-A9) showed potential as a biomarker for EGUS, as it could discriminate between healthy horses and those with the disease [14]. - **Oxytocin:** Healthy horses had higher salivary oxytocin concentrations compared to those with EGGD, suggesting a potential link between stress and disease [15]. - **Proteomic Changes:** Gel and liquid proteomics have identified numerous proteins in saliva and serum that change with EGUS and its treatment, including increases in vimentin (wound healing) and decreases in podocalyxin (tissue damage) post-treatment [16][17]. - **Fecal Occult Blood Tests (FOBTs):** A study evaluated the use of FOBTs as a predictor of EGUS. The results showed that neither clinical signs nor FOBTs had sufficient sensitivity or specificity to be used as a reliable screening tool for EGUS, reinforcing the need for gastroscopy [11]. While these biomarkers are promising, they are not yet ready for routine clinical use. They may, however, become valuable tools in the future for monitoring treatment response or screening high-risk populations, reducing the need for repeated gastroscopies [1][12][13][16][17][14]. ## Clinical Signs and Risk Factors Recognizing the clinical signs and risk factors for EGUS is critical for early intervention. ### Common Clinical Signs The clinical signs of EGUS can be vague and variable. Some horses may show no obvious signs at all, while others may exhibit severe symptoms [11][18]. Common owner-reported signs include: - **Girth aversion:** This is often considered a classic sign, with horses resenting being girthed or saddled [11]. - **Poor performance:** A decline in athletic ability or reluctance to work is a frequent complaint [11][19]. - **Weight loss and poor body condition:** This can occur despite a normal appetite [11]. - **Reduced appetite or picky eating:** Horses may be reluctant to eat grain or may eat slowly. - **Behavioral changes:** This can include dullness, aggression, or a change in temperament [3]. - **Recurrent mild colic:** Episodes of low-grade abdominal discomfort. - **Poor coat condition:** A rough, dull hair coat. It is important to note that a study using the Horse Grimace Scale (HGS) found no significant differences in pain scores between horses with and without gastric lesions [18]. This suggests that horses with EGUS may not display obvious facial pain expressions, making diagnosis based on visual assessment alone unreliable [18]. ### Key Risk Factors Several factors are known to increase the risk of EGUS: - **Intensive Training and Performance:** Racehorses and other high-performance athletes are at the highest risk [1][10][5][19]. The combination of high-concentrate diets, intermittent feeding, and the physical and psychological stress of training contributes significantly to ulcer development [2][8]. - **Intermittent Feeding:** Periods of fasting, even short ones, increase acid exposure to the squamous mucosa [2]. - **High-Concentrate Diets:** Diets high in grain and low in forage produce more volatile fatty acids, which can damage the squamous mucosa [2]. - **Stress:** Psychological stress from training, transport, social regrouping, and competition is a major risk factor, particularly for EGGD [3][2]. - **Non-Steroidal Anti-Inflammatory Drugs (NSAIDs):** Drugs like flunixin meglumine and phenylbutazone can disrupt the gastric mucosal barrier and lead to ulcer formation [4]. - **Recent Management Changes:** A study on Icelandic horses found that being in training for 4 weeks or less was a significant risk factor for ESGD compared to being in training for 5 weeks or more [8]. This suggests that the adaptation period to new training regimens is a high-risk time. - **Breed and Work Type:** While EGUS can affect any horse, studies show differences in prevalence and severity based on occupation. Horses in more intense jobs, such as group performances or pulling carts, had more severe ulcers [7]. In a study of working mules in Colombia, a significant prevalence of gastric ulcers was found, indicating that even non-racing equids are at risk [20]. ## Management and Prevention Strategies Effective management of EGUS goes beyond just administering omeprazole. A multi-modal approach is essential for successful treatment and long-term prevention. ### Dietary and Husbandry Modifications - **Maximize Forage Intake:** Horses should have access to pasture or hay almost constantly. Forage helps buffer stomach acid and reduces the risk of acid splash. The goal is to minimize the time the stomach is empty [2]. - **Reduce Concentrate Meals:** If grain is necessary, it should be fed in small, frequent meals rather than one or two large ones. This helps prevent a rapid drop in gastric pH. - **Decrease Stress:** Identifying and minimizing stressors is critical. This can involve maintaining a consistent daily routine, providing social companionship, and ensuring adequate turnout. ### The Role of Behavioral Medicine The interplay between EGUS and stress is complex. Horses with EGUS are often presented with a history of problem behaviors, some of which resolve following gastroprotectant therapy [3]. However, in some cases, problem behaviors persist even after gastroscopic resolution of the disease. These horses may have learned pain-related behaviors that continue even after the pain is gone [3]. A behavioral medicine approach, as described in a 2025 clinical commentary, can be beneficial for these chronic or refractory cases [3]. This includes: - **Management of underlying diseases:** Ensuring all medical issues are addressed. - **Environmental modification:** Reducing stressors in the horse's environment. - **Behavior modification:** Using training techniques to address learned behaviors. - **Behavior-modifying medication:** In select cases, medication may be used to help manage anxiety or stress [3]. This integrated approach recognizes that treating the stomach alone may not be sufficient for horses with chronic EGUS, especially when behavioral issues are present [3]. ### Nutraceutical Supplements The use of nutraceutical supplements for EGUS is an area of interest. A study investigated whether a nutraceutical supplement could reduce EGUS recurrence during an omeprazole withholding period [10]. The study found that the prevalence of ESGD post-RWP was lower in horses receiving the supplement than at the start of the study, suggesting a potential benefit [10]. However, more research is needed to determine the efficacy of various supplements. They should not be used as a replacement for proven therapies like omeprazole but may have a role as an adjunctive therapy [10]. ### The Danger of Unsafe Home Remedies There are many anecdotal "home remedies" for EGUS, but few have scientific backing. Some can even be harmful. It is crucial to avoid: - **Human Omeprazole:** Human formulations may not be bioavailable in horses and are not dosed appropriately. - **Antacids:** While they can provide temporary relief, they do not heal existing ulcers and require frequent dosing. - **Unproven Herbal Remedies:** Some herbs can interfere with other medications or have toxic effects. Always consult with a veterinarian before administering any medication or supplement to a horse with suspected or diagnosed EGUS. ## Prognosis and Long-Term Outlook The prognosis for EGUS, particularly ESGD, is generally good with appropriate treatment. Most horses show significant improvement or complete healing of squamous lesions after a 28-day course of omeprazole [5][2]. However, the prognosis for EGGD is more guarded, and the condition can be challenging to manage [1][2]. The key to a successful long-term outcome is a comprehensive management plan that includes: 1. **Accurate Diagnosis:** Confirming the type and severity of EGUS via gastroscopy. 2. **Appropriate Medical Therapy:** Using a proven formulation of omeprazole (like Gastrogard) at the correct dose and duration. 3. **Dietary and Environmental Changes:** Implementing long-term changes to reduce risk factors. 4. **Regular Monitoring:** Performing follow-up gastroscopy to confirm healing and adjust treatment as needed. Even with successful treatment, EGUS can recur, especially if the underlying risk factors are not addressed. A study on racehorses found that a short withholding period from omeprazole was enough to trigger recurrence [10]. Therefore, a proactive, preventative approach is essential for horses in high-risk situations. ## Limitations and When to Contact a Veterinarian This article provides a comprehensive overview of EGUS and its treatment with Gastrogard (omeprazole). However, it is educational and not a substitute for professional veterinary diagnosis and treatment. The information presented here cannot predict the specific condition of an individual horse. Breed, age, discipline, and individual health status can significantly influence the diagnosis, treatment plan, and prognosis. **You should contact your veterinarian immediately if your horse exhibits any of the following:** - **Acute, severe colic:** Signs of intense abdominal pain, such as rolling, pawing, and looking at the flank. - **Complete loss of appetite:** Refusal to eat or drink for more than 12 hours. - **Lethargy and depression:** A sudden and significant decrease in energy and responsiveness. - **Fever:** A rectal temperature above 101.5°F (38.6°C). - **Difficulty breathing** or any signs of respiratory distress. - **Weight loss** that is rapid or unexplained. These signs could indicate a more serious condition that requires immediate veterinary attention. Do not attempt to treat these symptoms at home. ## Frequently Asked Questions ### 1. What is the difference between ESGD and EGGD in horses? ESGD (Equine Squamous Gastric Disease) affects the upper, non-glandular part of the stomach and is primarily caused by acid splash. EGGD (Equine Glandular Gastric Disease) affects the lower, glandular part and is more complex, often linked to stress and inflammation [2]. ### 2. How is Gastrogard (omeprazole) administered to horses? Gastrogard is an oral paste that is administered directly into the horse's mouth. The standard dose is 4 mg/kg once daily, ideally on an empty stomach, for at least 28 days [4][5]. ### 3. How quickly does omeprazole work in horses? While omeprazole begins reducing acid secretion within hours, visible healing of ulcers typically takes weeks. A minimum 28-day course is standard, and a follow-up gastroscopy is recommended to confirm healing [5]. ### 4. Can EGUS be cured permanently? EGUS can be healed, but it can also recur, especially if the underlying risk factors (like stress, diet, or intense training) are not managed. Long-term prevention is often necessary for high-risk horses [10][2]. ### 5. Is a gastroscopy necessary to diagnose EGUS? Yes, gastroscopy is the only definitive method for diagnosing EGUS. It allows the veterinarian to visually inspect the stomach lining and grade the severity of the ulcers [11][2][7]. ### 6. Can I use human omeprazole for my horse? No. Human omeprazole formulations are not approved for horses and may have poor bioavailability. It is essential to use a veterinary-approved product like Gastrogard to ensure proper dosing and effectiveness. ### 7. What are the main risk factors for EGUS in horses? The main risk factors include intensive training, high-concentrate diets, intermittent feeding, stress, and the use of NSAIDs like flunixin meglumine [4][2][8]. ### 8. What should I do if my horse's ulcers do not heal with omeprazole? If ulcers do not heal after a course of omeprazole, it is important to consult your veterinarian. They may recommend a longer treatment course, additional therapies like sucralfate, or a more intensive investigation into underlying causes, including behavioral factors [1][3][6]. --- ## Related Clinical & Scientific Guides * [Equine Hematologic Disorders: Anemia and Coagulopathies](/knowledge/veterinary-medicine/equine-care/equine-hematologic-disorders-anemia-coagulopathies) * [Equine Lifespan: Factors Influencing Longevity in Horses](/knowledge/veterinary-medicine/equine-care/equine-lifespan-factors-influencing-longevity-in-horses) * [Miniature Horse Care Guide](/knowledge/veterinary-medicine/equine-care/miniature-horse-care)