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Equine Gastric Ulcers: Causes, Symptoms, and Prevention

Updated: Oct 27, 2023

Sport horse develops gastric ulcers

The first thing that comes to mind whenever horse digestive problems are concerned is colic. However, one of the most common conditions affecting nearly all horses globally is gastric ulcers. According to a study by the American Veterinary Medical Association (AVMA), 58% of show horses are diagnosed with gastric ulcers. Racehorses, performance, endurance, and even pleasure horses are affected by gastric ulcers. Using revolutionary diagnostic tools, it is now possible to diagnose equine gastric ulcers with precision. However, gastric ulcers are one of the most common ailments affecting high-performance horses at an alarming rate.

Why are horses prone to ulcers?

Horses are prone to developing gastric ulcers due to several factors related to their unique anatomy, physiology, and management practices. Understanding the equine digestive system is crucial for elaborating on why horses are susceptible to gastric ulcers.

horses graze to help neutralize acid in the stomach preventing ulcers
  • Continuous Grazing in the Wild: In their natural habitat, horses graze continuously throughout the day. This constant intake of hay or grass provides a steady flow of fiber into the stomach, which helps to buffer and neutralize the acidic secretions. This natural feeding pattern ensures that the stomach lining remains relatively protected from the corrosive effects of stomach acid.

  • High-Concentrate Diets: Domesticated horses are often fed diets that include high-concentrate grains, such as oats or corn. These grains can be more quickly digested and absorbed in the small intestine, leading to a reduction in the amount of fiber in the stomach. Without a continuous source of fiber to buffer the stomach acid, the acidic environment becomes more pronounced and can lead to ulcer formation. This is especially true when horses are fed large, infrequent meals of concentrates.

  • Stress: Horses are sensitive animals, and stress can significantly contribute to the development of gastric ulcers. Stressors such as intense training, transportation, changes in environment, or social interactions with other horses can elevate the production of stress hormones. These hormones can, in turn, increase gastric acid secretion and decrease blood flow to the stomach lining, making it more vulnerable to ulceration.

  • Limited Feeding Time: Some horses are subjected to feeding schedules with long intervals between meals. This practice can leave the stomach empty for extended periods, allowing the gastric acid to come into contact with the unprotected stomach lining, leading to ulcer development. Horses have evolved to graze for most of the day, so long gaps between meals can be detrimental to their digestive health.

  • Foal Vulnerability: Gastric ulcers can affect horses of all ages, including foals. Even young horses can develop ulcers, and their vulnerability is attributed to factors like stress, weaning, and dietary changes. Foals often face changes in their living environment and feed, which can disrupt their natural feeding patterns and increase the risk of ulcers.

In summary, gastric ulcers in horses are primarily caused by the erosion of the stomach's inner lining due to prolonged exposure to stomach acids. Horses are naturally grazers, and their digestive system is adapted to continuous foraging, which helps protect the stomach lining from the corrosive effects of acid. However, modern feeding practices, high-concentrate diets, stress, and limited feeding times can disrupt this natural balance and make horses more prone to developing gastric ulcers. Understanding these factors is essential for preventing and managing equine gastric ulcers.

Equine digestive system anatomy
Photo credit: SmartPak

Anatomy of the Equine Digestive System

The equine digestive system is divided into foregut and hindgut. The foregut consists of the mouth, esophagus, stomach, and small intestine. The small intestine makes its way to the hindgut which includes the caecum, colon, and rectum. A major portion of the horse feed is fermented in the hindgut with the help of bacteria, yeast, and protozoa.

equine stomach has non-glandular and glandular regions
Photo credit: SmartPak

Interestingly, horse’s stomach is further divided into two parts: the lower part is glandular that comprises two-third of the stomach where the acid is secreted. It has a thick protective mucosal covering that acts as a barrier for sensitive stomach tissues. Ulcers can be found here but they aren’t common. The upper part or non-glandular part, where the mixing of the stomach’s contents takes place, is more prone to acids due to its thin protective lining. It is the region where ulcers mostly occur.

Other than gastric ulcers another type is colonic ulcers. Colonic ulcers remain undiagnosed due to their vague signs, unavailability of sufficient diagnostic tools, and limited usage. It is vital to differentially diagnose colonic ulcers because medications for gastric ulcers do not work for colonic ulcers.

Causes of Ulcers in Horses

Equine gastric ulcer is a frequently occurring health condition faced by many horse owners, breeders, and caretakers and a variety of factors can play part in ulcer development. Following are some of the significant causes of gastric ulcers in horses:


Primary Cause: Stress is the leading cause of gastric ulcers in horses. Horses are highly sensitive animals, and various stressors can negatively impact their gastrointestinal health. When horses experience stress, they are less likely to eat and may alter their natural feeding patterns, leading to prolonged periods of an empty stomach.

Training Stress: According to equine medicine researcher Frank Andrews, one of the primary sources of stress leading to gastric ulcers is intensive training. The stress associated with training can trigger chemical changes in the horse's body, including increased cortisol levels in the blood. Elevated cortisol levels are akin to increased serum gastrin, which, in turn, stimulates the production of hydrochloric acid in the stomach, creating a more acidic environment conducive to ulcer formation.

Other Stressors: Apart from training stress, horses can face various other stressors, such as transport stress (during long journeys), stall confinement (restricting natural movement), and social or environmental changes. All of these stressors can contribute to the development of gastric ulcers.

exercising horses on lunge line

High Exercise

Common in Athletic Horses: Horses involved in athletic activities like racing, endurance riding, and show competitions are at a higher risk of developing gastric ulcers. The physical demands of these activities can be intense and often involve rigorous training and competition schedules.

Acid Production: Exercise can lead to increased acid production in the stomach due to several factors. Horses that are involved in high-intensity exercise tend to graze less, which can result in reduced buffering of stomach acid. Additionally, the physical exertion of exercise can decrease blood flow to the gastrointestinal tract, further disrupting the natural protection mechanisms of the stomach lining.

Acid Exposure: During exercise, the motion and jostling of the horse's stomach can cause acid to splash and expose the upper, more vulnerable portion of the stomach to the acidic environment. This can lead to the erosion of the stomach lining and the development of ulcers in the upper region of the stomach.

Low Grazing

Continuous Acid Production: A horse's stomach continuously produces gastric acid, even when the horse is not eating. This acid production is essential for the digestion of food and can amount to several gallons of acidic fluid per day. This means that the horse's stomach is constantly exposed to acid, which is buffered during normal grazing and feeding.

Natural Buffering: When a horse grazes on grass or forage, it not only ingests food but also generates saliva, which has a buffering effect on stomach acid. Additionally, the fiber content in the feed provides a physical barrier that helps protect the stomach lining from the corrosive effects of acid.

Boarding Situations: In many boarding situations, horses are often fed two or three times a day with extended gaps between meals. During these periods without feed, the horse's stomach remains empty, allowing the acid to come into contact with the stomach lining. This lack of continuous buffering and the presence of acid can make the stomach more vulnerable to ulcer formation.

High Grain Diet

Excess Grain: High-grain diets can contribute to the development of gastric ulcers in horses. Grains, such as oats and corn, are easily digestible and can produce an excess of fatty acids. These fatty acids can lower the pH in the stomach, making it more acidic, and potentially leading to ulcer formation.

Reduced Fiber: In diets with high grain content, there is often a reduction in the amount of fiber. As mentioned earlier, fiber is crucial for buffering stomach acid and protecting the stomach lining. With a decreased fiber intake, the natural protective mechanisms are compromised, leaving the stomach more susceptible to ulcers.


Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): Chronic administration of certain NSAIDs, such as Ketoprofen, Banamine, and Phenylbutazone, can negatively affect the stomach lining. These drugs are commonly used to manage pain and inflammation in horses. They work by inhibiting enzymes that produce inflammatory substances. However, one side effect is that they can reduce the production of the protective mucosal layer in the stomach, leaving the stomach more prone to ulcers.

NSAID Use: When horses are treated with NSAIDs over an extended period, it can lead to a reduction in the stomach's ability to protect itself from the corrosive effects of acid. As a result, the stomach lining becomes more vulnerable to ulceration.

Signs and Symptoms of Equine Ulcers

Signs and symptoms of equine ulcers can vary in severity, and while many horses may not exhibit overt clinical signs, there are both subtle and more serious indicators to watch for:

ulcers in equine stomach can cause pain
Photo credit: SmartPak

Subtle Signs

  • Loss in Appetite and Feed Intake: Horses with gastric ulcers may eat less and show a reduced interest in their feed. They may pick at their food and leave it largely untouched.

  • Dull Attitude and Lethargy: Horses that are experiencing discomfort due to ulcers can appear lethargic and have a general lack of enthusiasm. Their demeanor may be less lively than usual.

  • Resistance to Training and Workout: Ulcer-afflicted horses may exhibit resistance or discomfort during training sessions or physical activity. They might be unwilling to perform tasks they normally do without hesitation.

  • Weight Loss and Anemia: Chronic gastric ulcers can lead to weight loss and, in severe cases, even anemia. The reduced appetite and impaired nutrient absorption contribute to these conditions.

  • Low-Grade Colic: Some horses may experience intermittent bouts of mild colic, which can be a sign of gastrointestinal discomfort caused by ulcers.

  • Preference for Hay: Horses with ulcers may favor hay over grain or other concentrates. The longer chewing time required for hay can help produce saliva, which provides a natural buffer for stomach acid.

  • Cribbing and Wind Sucking: These are stereotypic behaviors observed in horses under stress or discomfort. Cribbing and wind-sucking can be a response to the discomfort caused by ulcers.

  • Excess Salivation: Increased salivation may occur as a response to gastric discomfort, as the horse tries to alleviate irritation in the stomach.

  • Diarrhea: Ulcers can disrupt normal digestion and lead to gastrointestinal issues, including diarrhea.

Serious Signs

  • Abdominal Pain: Horses with severe gastric ulcers may exhibit more obvious signs of abdominal pain, which can manifest as restlessness, pawing, or rolling. This is a more pronounced sign of significant discomfort.

  • Grinding of Teeth (Bruxism): Some horses will grind their teeth, a condition known as bruxism, when experiencing pain or discomfort, including that caused by gastric ulcers.

  • Recumbency: In extreme cases, especially among young horses, some may lie on their backs as a way to find relief from severe gastric ulcers. This position can alleviate some of the pain and discomfort they are experiencing.

  • Refusal to Eat: Horses with severe ulcers might walk away from their feed when it reaches their stomach, as the act of swallowing can be painful for them.

It's essential for horse owners and caretakers to be vigilant for these signs, especially in situations where horses are subjected to stress, high-intensity exercise, or other risk factors for ulcers. Prompt diagnosis and appropriate treatment can help alleviate the discomfort and improve the horse's overall well-being. Consulting with a veterinarian for a thorough evaluation and diagnosis is crucial if there is suspicion of equine gastric ulcers.

Why do ulcers remain undiagnosed?

The undiagnosed nature of equine ulcers is a common issue, and several reasons contribute to this phenomenon:

  • Subtle Symptoms: One of the primary reasons ulcers remain undiagnosed is that the symptoms are often subtle and can be mistaken for other common equine health issues. Horses are prey animals, and they tend to hide their discomfort. As a result, owners may not notice the signs of gastric ulcers until they become more pronounced.

  • Non-Verbal Communication: Horses cannot verbally communicate their discomfort, so they cannot directly convey their pain or distress to their owners. They rely on body language and behavior changes, which can be misinterpreted or overlooked.

  • Masking as Other Conditions: The symptoms of equine ulcers, such as changes in appetite, mild colic, and lethargy, can mimic other conditions like parasitism or colic. This similarity in symptoms can lead to misdiagnosis or delayed diagnosis.

  • Lack of Awareness: Some horse owners may not be fully aware of the prevalence and subtlety of gastric ulcers in horses. This lack of awareness can result in ulcers not being considered as a potential issue when a horse displays symptoms of discomfort.

  • Stress and Lifestyle Factors: Many horses are exposed to stressors, such as high-intensity exercise, changes in routine, and transport, which can increase the risk of ulcers. These stressors can contribute to the development of ulcers, and if not recognized, the underlying issue remains undiagnosed.

  • Preventative Measures: Some horse owners may take preventative measures, such as providing access to forage and managing feeding schedules, to reduce the risk of ulcers. While these measures are beneficial, they can also mask the symptoms of ulcers, making them less apparent.

To diagnose equine gastric ulcers, a veterinary procedure known as gastroscopy is used. Gastroscopy involves the use of an endoscope, a thin, flexible tube with a camera at the end, which is inserted into the horse's stomach. This procedure allows for direct visualization of the stomach lining. Gastroscopy is considered the most reliable method for diagnosing ulcers as it provides a clear view of any lesions or abnormalities on the stomach's surface. It is a relatively simple and minimally invasive procedure, and the results are typically conclusive.

In summary, equine ulcers often remain undiagnosed due to their subtle symptoms, the inability of horses to communicate their discomfort, the potential for misdiagnosis, and a lack of awareness. Gastroscopy, a diagnostic procedure conducted by a veterinarian, is the most effective way to definitively diagnose gastric ulcers and ensure appropriate treatment.

Prognosis for Gastric Ulcers

The prognosis for gastric ulcers in horses is generally favorable, and with proper diagnosis and treatment, most horses can recover fully. Here's an elaboration on the prognosis for equine gastric ulcers:

vet checking for gut sounds in a horse with stomach ulcers
  • Treatment Options: Equine gastric ulcers can be effectively treated with the help of medications and management changes. The most common treatment involves the use of medications called proton pump inhibitors (PPIs) or histamine receptor antagonists. These drugs reduce the production of stomach acid, which allows the ulcers to heal. Treatment duration may vary depending on the severity of the ulcers, but many horses start to show improvement within a few days of beginning treatment.

  • Management Techniques: In addition to medication, making changes in the horse's management practices can significantly contribute to the healing process and reduce the risk of recurrence. Simple management techniques, such as increasing access to forage, reducing stress, and maintaining a consistent feeding schedule, can help prevent the reoccurrence of ulcers.

  • Healing Time: The time it takes for a horse to heal from gastric ulcers can vary depending on several factors, including the severity of the ulcers, the horse's overall health, and the effectiveness of the treatment. In many cases, horses start to show improvement within a few weeks, and most can heal within a month of appropriate treatment.

  • Monitoring and Follow-up: After the initial treatment, it's essential to continue monitoring the horse's condition and work closely with a veterinarian to ensure that the ulcers are healing as expected. Follow-up gastroscopy examinations may be necessary to confirm that the ulcers have resolved completely.

  • Prevention: Equine gastric ulcers can be prevented through proper management practices. This includes providing continuous access to forage, minimizing stress, maintaining a consistent routine, and ensuring a balanced diet. Prevention is often more effective and cost-efficient than treating ulcers once they have developed.

  • Individual Variability: It's important to note that the prognosis can vary from one horse to another. Some horses may have a more severe form of ulcers or other underlying health issues that can influence their response to treatment. The overall health of the horse and the owner's commitment to implementing management changes also play a role in the prognosis.

In summary, the prognosis for equine gastric ulcers is generally positive, with most horses responding well to treatment and management changes. The key to successful management is early diagnosis, appropriate treatment, and a focus on prevention to minimize the risk of ulcers recurring in the future. Collaborating with a veterinarian and following their guidance is crucial for achieving the best possible outcome for a horse with gastric ulcers.

How to Prevent Gastric Ulcers in Equines

Horse owners can utilize the following management techniques to prevent gastric ulcers:

  • Avoid or control the use of anti-inflammatory drugs. Use only medications approved by the FDA if there is no other option except administration, use safer medications like firocoxib, that too under the vet’s recommendations

  • Limit stressful situations like frequent transportation and intense training sessions.

  • If you choose to stall them, make sure they see and socialize with other horses and also have access to grazing.

  • Balance their grain and concentrates intake and provide them with sufficient hay. Whatever you choose to add or deduct from their diet, always ask for your veterinarian’s recommendations.

  • Don’t keep the animal off-feed for an extended duration and feed them frequently or provide sufficient grazing time.

  • Ensure round-the-clock access to clean water.

  • Provide hay nets while traveling transportation for competitions and shows.

  • Avoid horse training and workout with an empty stomach.

Holistic Approach to Preventing Ulcers

preventing equine ulcers with red light therapy and photopuncture

Holistic approach to preventing ulcers in horses involves considering the overall well-being of the horse and addressing not only the physical aspects but also the emotional and mental factors that can contribute to a horse's health. Here's an elaboration on holistic methods for preventing ulcers in horses:


Acupressure is a holistic therapy that involves applying pressure to specific points on the horse's body, known as acupoints. These points are believed to be connected to various organs and systems, and stimulating them can help promote balance and overall well-being.

Acupressure can be used to alleviate stress and anxiety in horses, which are known risk factors for the development of gastric ulcers. By reducing stress, acupressure may indirectly contribute to ulcer prevention.

You can learn acupressure from a Nationally Certified Animal Acupressure Practitioner. We teach hands on clinics in the southeast US. Check out our events page for upcoming events!


Photopuncture is a non-invasive holistic therapy that uses light to stimulate acupoints. Light therapy is believed to influence energy flow in the body and promote healing and balance.

Similar to acupressure, photopuncture can be used to address stress and anxiety in horses, which can help prevent ulcers by reducing emotional and mental stressors.

Holistic Practitioners

  • Holistic practitioners, such as veterinarians or therapists, take a comprehensive approach to horse care. They view the horse as a whole being, considering not only physical symptoms but also emotional and mental well-being.

  • Holistic practitioners gather extensive information about the horse's history, behavior, and physical condition. They may assess the horse's coat, hooves, eyes, and other physical characteristics to identify imbalances or potential health issues.

  • They consider how different parts of the horse's body feel, whether they are warm or cool to the touch, which can provide insights into circulation and energy flow.

  • Even the horse's scent and overall demeanor can be evaluated as indicators of their health and well-being.

Holistic approaches can complement traditional veterinary care and may help identify early signs of stress or imbalance that could lead to ulcer development. By addressing these factors, horse owners can create a more supportive and balanced environment for their horses, potentially reducing the risk of ulcers.

It's important to note that holistic practices should be used in conjunction with conventional veterinary care, and any treatment or therapy should be performed by qualified and experienced practitioners. Collaborating with a holistic practitioner as part of the horse's healthcare team can provide a more comprehensive approach to ulcer prevention and overall equine well-being.

healthy horse is on a good diet to prevent ulcers

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