Last program I talked about gastric ulcers in exercising horses and mentioned that horses are more susceptible than humans because a portion of their stomach is unprotected. Part of the horse’s stomach is nonglandular and is less protected than the glandular portion. Also, Dr. Mike Davis from Oklahoma State indicates that with exercise, the pressure increases in the stomach and stomach acid contacts the nonprotected portion. Food can help buffer the acid somewhat, so it is a good idea to have some hay or pasture available for your horse at all times, even just prior to exercise. The stress of exercise also causes an increase in the hormone cortisol and cortisol decreases the stomach’s protection from acid.
As far as treatment, the most effective drug is omeprazole, which is sold under the trade name GastroGard. Omeprazole is acid sensitive and the form used must prevent it from being destroyed by stomach acid. GastroGard has been shown to be absorbed but is expensive. Because of this, many people have tried to use compounded omeprazole. However, compounded omeprazole is not effective because it is destroyed by the stomach acid. GastroGard should be given on an empty stomach and is effective when given only once a day. Human products such as ranitidine and famotidine are effective in horses but must be given three times daily. There are many products marketed in the horse magazines for preventing ulcers. Unfortunately, they only work if given every 1 to 2 hours because they only work while they are actually in the stomach. Most of the claims of these products being effective by dosing only two to three times daily are not supported by scientific studies.
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