Gastric ulcers in horses can arise when the lining of a horse’s stomach begins to become eroded due to prolonged exposure to stomach acid.¹ There are several conditions which give rise to this; though most of these are lifestyle-related, the repeated use of nonselective NSAIDs in horses for pain management also contributes to this problem.

Also called equine gastric ulcer syndrome (EGUS), gastric ulcers in the horse are most closely associated with athletic horses, horses under inordinate stress and horses with comorbidities (other illness). “Prevalence in unmedicated racehorses in active training is at least 90%, whereas that in non-racing performance disciplines exceeds 60%. Neonatal foals are at significant risk for development of perforating peptic ulcers until they are several weeks old, because their gastric mucosa is not developed to full thickness at birth. Although spontaneous healing of peptic ulcer lesions has been noted, if the horse is maintained in the circumstances inciting EGUS, the lesions are unlikely to heal without medical intervention.”²

Horses and Gastric Ulcers

Since horses are natural grazers, they typically eat throughout the day. Thus, they have evolved to secrete stomach acid all day long. This can be problematic due to the periodic feeding regimen of nearly all horses that work or perform for a living. 

A horse’s stomach is made up of two parts representing upper and lower segments. The lower portion is glandular; it secretes stomach acid and has a protective coating to keep it from being damaged by acid.  “Ulcers do occur in the glandular portion of the stomach, but this is less common.  The top portion of the stomach is designed for mixing of the contents of the stomach and does not have as much protection from the acid. This is the most common place to find gastric ulcers.”¹ Additionally, the high-grain diets that many horses are fed produce volatile fatty acids that can contribute to the development of ulcers.

Stall confinement can exacerbate the risks for EGUS in horses. This aspect of horse husbandry causes stress, because horses are social animals that are unused to solitary living in their natural setting. When horses are fed two times a day (as so many are), the stomach lining is subjected to a prolonged period without feed to neutralize stomach acid.^1,2

NOTE: Cimetidine is a CLASS 5 DRUG under the Association of Racing Commissioners International (ARCI) Uniform Classification Guidelines for Foreign Substances (UCGFS).

Where to buy Cimetidine

Cimetidine is available in the U.S. through pharmaceutical manufacturers and through veterinary custom compounding companies. 

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

¹aaep.org.

²Merck Veterinary Manual.