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Antibiotic Use and Gastric Ulcers in Horses

Antibiotic Use and Gastric Ulcers in Horses

Hoyt Cheramie, DVM, MS, Dipl. ACVS

Horses on antibiotics might experience feeding as well as increased stress, which are associated with gastric ulcer development. Do you need to be concerned about your horse developing gastric ulcers from being on a course of antibiotics? What, if anything, can you do to combat the development of ulcers?



The judicial use of systemic antibiotic administration is often a critical component of successfully treating bacterial infections in horses. Along with the substantial benefits however, there are also potential adverse effects of antibiotic therapy. Diarrhea/colitis are likely the most common of these side effects, but kidney, liver, and neurologic effects, along with several other rare reactions, may be encountered. Conversely, there is no published evidence that administration of antibiotics in horses is associated with development of equine gastric ulcer syndrome (EGUS) in either form, equine squamous gastric disease, or equine glandular gastric disease. When administering antibiotics to horses, always follow your veterinarians’ instructions to minimise the risk of adverse effects.

Combating the development of ulcers is closely tied to two things—managing how we feed our horses and alleviating stress in our horses’ lives.

In their natural state horses graze the majority of the day, producing large amounts of saliva and taking in enough grass to help protect the upper, acid-sensitive portion of the stomach from acid. Because a horse’s stomach produces acidic gastric fluid continuously, and in quantities of up to 16 gallons per day, the salivary buffering and physical protection is important to maintaining a healthy digestive system. When we practice episodic feeding with “dried” roughage and/or concentrated feeds, we interrupt the natural ability of the horse to buffer acid in the upper portion of the stomach. Providing access to grazing, hay in slow feeder nets or bins, and feeding small concentrate meals throughout the day are recommendations to decrease ulcer development risks.

Another way to help prevent ulcers is to reduce stress as much as possible. Even what we might consider small things, such as storms, changes in feeding times, moving to a different pasture, or changing a turnout buddy, can also lead to stress, which can lead to the development of ulcers.

Sticking to a routine as much as possible with our horses’ work, training, feeding, and turnout schedules can help. Horse owners can also download Relax Trax, a music soundtrack developed by an animal sound behaviorist specifically for horses.

It’s available for free here. Consult your veterinarian if you think an approved gastric ulcer prevention could be beneficial to your horse’s circumstance.