Understanding and Normal Gastrointestinal Function in Horses

Even when there are no obvious signs of gastrointestinal issues they can interfere with performance by affecting training, appetite and temperament.  Some issues may naturally pass if horses are turned out to pasture for an extended period of time, but they usually don’t lessen in horses that continue training.

Why do so many horses get ulcers?

Acid is normally produced 24 hours a day in the horse’s stomach as a part of the digestive process.  When too much acid is present, ulcers result. Overproduction of stomach acid has many and various causes.  If you suspect a more serious condition you should consult your veterinarian.

Factors that increase a horse’s risk for stomach ulcers include:

  • Feeding:  Infrequent grazing or reduced hay intake can lead to stomach ulcers within hours or days. 
  • Training:  Intense exercise actually increases acid production in the horse’s stomach.  Performance horses often go without feed several hours of each day during training, permitting acid buildup within the stomach causing more damage.  In addition, exercise reduces blood flow to the stomach, but the effect this has on ulcer formation is not known. 
  • Physical Stress:  Foals or adult horses that are sick, injured, hospitalized or in pain often get ulcers.  The use of certain medications can alter the delicate digestive tract creating a welcome environment for ulcers. 
  • Changes in growing foals: The stomach and entire digestive tract of young foals is still developing and is easily injured by acid and enzymes. 
  • Other Factors:  Hauling, extended time in stalls, show rings and show environments, changes in normal activity or feed all expose horses to stresses that may contribute to ulcers. 
 

How can I tell if a horse has stomach ulcers?

If a horse is in training, the chances are high that it has stomach ulcers even if symptoms seem to be absent.  Often it’s clear only in hindsight, after treatment results in improved attitude, condition or performance.  In fact, by the time obvious symptoms appear, stomach ulcers may be advanced and more difficult to treat.  So, if in doubt, suspect ulcers until proven otherwise.


  • Endoscopy: Examination of the stomach through an endoscope can confirm ulcers.
  • Medication: Any improvement after treatment with an effective anti-ulcer medicine suggests that the horse has stomach ulcers, but does not mean that the ulcers have healed.  Healing usually requires continued treatment for a period of at least a month, especially when the horse remains in training.
 

How should stomach ulcers be managed?

  • Reduce acidity to allow healing to occur
  • Reduce obvious sources of stress that cause symptoms
  • Change stable management procedures that reduce stress in the horses (i.e., provide greater access to hay and/or pasture, more turn out time)
  • Reduce difficult workouts until the stomach has healed
  • Prevent ulcer from returning by controlling stomach acid at its source 
    Ensure complete stomach healing with consistent preventative care.