Gastric ulcers, also called stomach ulcers, are a painful and common condition in many horses.

The American Association of Equine Practitioners (AAEP) estimates nearly 90% of all race horses, or horses involved in similar heavy training and competition, suffer from gastric ulcers. They further estimate nearly 60% of all horses of all ages also suffer from gastric ulcers. Simply put, a gastric ulcer is a painful lesion (sore) that occurs in the stomach of a horse.

The reason ulcers are so common is generally because of how horses are typically fed, which is usually two large meals per day. A horse’s digestive tract is designed to process small meals that they would naturally eat all day. The stomach of the horse is rather small, holding only up to about 3 gallons (12 liters) of feed at any given time. The stomach is also divided into two portions:

  • Lower glandular region, making up the lower 2/3 of the stomach. Here is where the stomach secretes hydrochloric acid (HCL) and pepsin to begin digestion of fats and proteins. It also produces mucus and bicarbonate, which offers some protection from HCL. 
  • Upper non-glandular region makes up the upper 1/3 of the stomach, has no secretory function and thus, does not have any protection against the acid produced in the stomach.

Under natural conditions, forage would be consumed by the horse, mixed in the stomach with HCL and pepsin, and quickly passed into the small intestine. Feed normally stays in the horse’s stomach for as little as 30 to 45 minutes. Because horses are usually only fed two times per day, they typically go for long periods without any feed passing within the stomach. Yet, HCL is still being secreted. With an empty stomach for long periods of time, the stomach acids can and do erode the stomach lining. This leads to the ulceration we see today.

There are usually other contributing factors to the causes of gastric ulcers. One is exercise. When a horse trains or exercises without any feed in its stomach, the gastric juices splash up into the upper portion of the stomach, thus exposing the non-glandular region to HCL. Stress can also be a contributing factor by reducing the amount of mucus produced in the stomach. Mucus acts as a buffer against acid. Stress inducing scenarios, such as stalled horses who receive little to no social interaction or even transport stress, are often cited as contributing factors to gastric ulcers. Finally, similar to stress, the use of non-steroidal anti-inflammatory medications like phenylbutazone (Bute) also act to reduce mucus production and, thus, leave horses prone to gastric ulcers.

Subtle signs that your horse may be suffering from gastric ulcers include:

  • Poor appetite
  • Poor body condition
  • Poor hair coat
  • Lethargic or irritable
  • Decreased performance

If you suspect your horse is suffering from gastric ulcers, it is critical you discuss this with your equine veterinarian. The only way to diagnose gastric ulcers is through an endoscope exam. This is a relatively simple procedure that is not very invasive. It consists of the veterinarian guiding a gastric endoscope down the horse’s esophagus and into the stomach. Here, the veterinarian can view the stomach lining of the horse to evaluate it for any ulceration. Gastric ulcers most often appear in the upper non-glandular portion of the horse’s stomach and while the lower glandular region can develop ulcers, they are much less common.

There are medications approved within the United States for the treatment of gastric ulcers, but they can be quite expensive. It is best to discuss these options with your veterinarian. However, prevention is the best medicine for gastric ulcers. Here are some preventive steps you can take:

  • Allow horses to graze on pasture, which provides them with small meals throughout the day. If pasture is not available, then provide free-choice hay. If hay quantity is limited, you can also consider using hay nets to extend hay feeding times and can learn more by reading our Hay Nets: Are They Good or Bad article. 
  • Feed your horse more frequently. You can learn more by reading our Feeding Your Horse Often article.
  • Reduce stress on your animal. For stalled horses, try to arrange times where your horse can socialize with other horses. Be mindful of transport times and intensity of exercise.
  • Be cautious of the use of non-steroidal anti-inflammatory medications.

Finally, feeding a lower NSC (non-structural carbohydrate) feed can reduce ulcer risk. Tribute® prides itself on developing high quality equine feeds based on the latest research. You can learn more about our research in developing feeds for horses prone to gastric ulcers by reading our Low NSC for the Performance Horse article.

If you are concerned about what you are feeding your horse and their risk for gastric ulcers, please reach out to us directly so we can assist in developing and personalizing a feeding plan for your animal.

Chris J. Mortensen, Ph.D.