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Stomach Ulcers and Fractured Bones in Horses: What's the Link?By Kentucky Equine Research Staff · October 21, 2015

Common in horses, stomach ulcers lead to poor appetite, loss of condition, low-level colic, and behavioral and physiological changes that might affect performance. Fortunately, omeprazole is an effective medication for the treatment of ulcers in horses. Low-dose omeprazole has even been proven to protect healthy horses from developing stomach ulcers. Many horses are administered omeprazole 365 days a year, and this leads to concern about side effects.

“One concern associated with the use of omeprazole in humans and experimental animals is that long-term administration, more than one year, will decrease bone mineral density and increase fracture risk,” explained Peter Huntington, B.V.Sc., M.A.C.V.Sc., director of nutrition at Kentucky Equine Research (Australia).

Omeprazole is thought to have either a direct effect on a particular enzyme in the bone or is believed to reduce the absorption of dietary calcium in the small intestine, resulting in a negative calcium balance.

Horses are clearly not the same as humans, but could horses treated with omeprazole have a higher risk of fracture than untreated horses? On the other hand, what happens to horses with stomach ulcers that aren’t treated with omeprazole?

To help owners answer these questions and evade the double-edged sword, researchers from Iowa State University* administered 4 mg/kg body weight of compounded omeprazole paste once daily for 60 days to horses kept in small paddocks.

Compared to horses given a placebo, horses treated with omeprazole did not have significantly lower calcium blood levels and did not have any difference in bone density.

Researchers concluded that “short-term administration of omeprazole does not significantly affect serum total calcium and ionized serum calcium concentrations nor does it affect bone density…in normal horses.”

That said, there is no guarantee that longer-term administration of omeprazole, a different form of the drug (e.g., a different formulation), or use in exercising horses would yield the same results.

“In humans, one study found that increased risk of fracture was not seen until after one year of treatment. Many horses stay on omeprazole for much longer than 60 days,” said Huntington.

Other strategies to combat gastric ulcers include dietary changes and digestive supplements such as RiteTrac, developed by KER. Horse owners in Australia should look for research-proven supplements available in their area.

Another approach to the management of stomach ulcers is the use of sucralfate, either with or without omeprazole, for hard-to-heal ulcers, especially those in the squamous region of the stomach. A new sucralfate/antacid combination, Sucralox, provides advanced digestive support and is available in Asia but not yet in North America and Australia.

*Caston, S.S., D.C. Fredericks, K.D. Kersh, et al. 2015. Short-term omeprazole use does not affect serum calcium concentrations and bone density in horses. Journal of Equine Veterinary Science. 35:714-723.