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Keeping Your Horse's Gut Healthy

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Did you know? Gastric ulcers are a problem to many performance horses, and affect up to 60% of show horses and 80-90% of racehorses. As the weather changes and we transition from winter into spring, staying on top of your horse's gut health is crucial. 

Gastric equine ulcers typically cause mild to moderate nonspecific symptoms such as:

  • Poor performance
  • Poor body condition
  • Poor quality haircoat
  • Teeth grinding
  • Biting at the sides
  • Mild intermittent colic and reluctance to finish a meal.
While these symptoms may appear mild, gastric ulcers are a significant source of pain and discomfort for affected horses. Certainly, people with stomach ulcers can relate!

Although people with stomach ulcers can relate to the pain and discomfort these horses feel; the causes, prevention, and treatments are a little different due to the different anatomy and physiology of the equine stomach.


  • STOMACH ACID: Horses continually produce stomach acid, even when they are not eating – up to 9 gallons of acidic fluid a day! The horse’s gastrointestinal system was designed for the horse to be grazing all day, so the saliva and forage buffer the constant stomach acid. Feeding horses two meals a day with prolonged periods on an empty stomach will allow excessive, unbuffered acid buildup that can damage the lining of the stomach.
  • STOMACH ANATOMY: Horses have two distinct portions of the stomach. The glandular portion, like the human stomach, produces the acid, but also produces the bicarbonate and mucous that protect the stomach lining. The squamous portion, which is the top portion, of the stomach does not have this protective barrier and is only protected by the saliva the horse swallows. Most ulcers are found in this area of the stomach. When a horse is very active, the stomach contents will splash around more, splashing up on the squamous portion, increasing the exposure to stomach acid. Understanding the anatomy of a horse’s stomach, we can see why the most common causes for stomach ulcers in the horse are intermittent feeding and intensive training.

To diagnose gastric equine ulcers in horses, a horse must be fasted for at least 24 hours so that a veterinarian can use a 3-meter endoscope to examine the stomach lining for ulceration.

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Once equine ulcers are diagnosed, treatment must be based on preventing the causes. The following are the basic guidelines:

  1. Allow free choice access to pasture or hay.
  2. Feed alfalfa hay instead of (or in addition to) grass hay.
  3. Reduce the amount of grain in the diet.
  4. Limit stressful situations, like stall confinement and isolation from other horses.
  5. Limit, or discontinue if possible, anti-inflammatory pain medications such as “bute.” Ask your veterinarian for safer alternatives that do not have the side effects of causing stomach ulcers.
  6. Talk to your veterinarian about medications to treat the ulcers. Medications fall into 3 basic classes. The first are antacids. Antacids in horses do not work well or for very long, so are typically not beneficial on their own. Because the horse constantly secretes stomach acid, the antacids must be given every few hours to be effective. The second class is histamine type 2 (H-2) receptor blockers. These medications partially block acid production in the stomach, but need to be given three times a day to be partially effective. The last class, and most beneficial, are the proton pump inhibitors (omeprazole). These medications, while expensive, are very effective and only need to be given once a day. Treatment should be continued for a full month, until a recheck gastric endoscopy reveals complete healing. Horses with a history of ulcers should be treated preventatively during high stress situations like trailering, racing, showing, intensive training, and stall rest. Knowing the high incidence of gastric ulcers and other medical conditions in stalled horses, most horses (except for in certain medical circumstances) should ideally be kept on pasture or with free choice access to hay.

Although it may not directly help with ulcers in horses, supplementing with a probitic supplement such as Opti-Zyme will help support an overall healthy GI tract minimizing digestive stress and the balance of bacteria and flora.

Opti-Zyme contains a source of naturally occurring viable yeast, enzymes and beneficial bacteria (probiotics) that encourage effective absorption within the equine digestive tract. 


In addition to ulcers, a horse can have in imbalanced gut for many reasons.  Formulated to enhance the digestibility of hay and grain, the addition of Opti-Zyme® to your horse's diet can help him maintain optimal body condition.  Probiotic support is also encouraged in possibly stressful situations involving the following:

  • Antibiotics
  • De-worming
  • Feed changes
  • Weather changes
  • Overall stress that may cause your horse to be susceptible to digestive upset from hauling, shows, stall rest, fever etc
  • Dehydration
Enzymes give your horse a head start when eating supplemental grain and will allow more starch to be absorbed in the small intestine (the 'safe zone' for starch absorption) which keeps it out of the hind gut where it can cause acidosis that may be a factor in founder, laminitis, and hind gut ulcers.


Although it may not directly help with ulcers in horses, supplementing with a probitic supplement such as Opti-Zyme will help support an overall healthy GI tract minimizing digestive stress.

ulcers in horsesManna Pro Opti-Zyme is:

  • Fortified with Probiotics, Viable Yeast and Enzymes
  • Formulated to enhance the digestibility of hay and grain
  • Helps maintain body condition on less feed
  • 48 day supply for one mature horse
  • Click here to download a $2 coupon and enter to win 3 free bags to get you through the spring!

 CLICK HERE to find a Manna Pro dealer near you!

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Dr. Shannon Baker DVM

Dr. Shannon Baker DVM

Dr. Shannon Baker graduated from the University of Missouri, College of Veterinary Medicine in 2002 with her DVM degree. After vet school, she completed an Equine Internship at MU. She currently owns Heartland Veterinary Services, a full service equine ambulatory practice with an emphasis in equine dentistry.


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