Omeprazole and Calcium Digestibility: What Horse Owners Should Know

Omeprazole, the only FDA-approved drug for healing gastric ulcers in horses, may cause reduced calcium digestibility, according to a recent study conducted at Kentucky Equine Research. What does this finding mean to horse owners who rely on the medication to keep their horses healthy?

Gastric Ulcers in Horses and Omeprazole

Researchers estimate 40-90% of horses have gastric ulcers, with those engaged in certain athletic disciplines, such as racing, at higher risk. Excessive gastric acid production ranks as a primary trigger for the development of ulcers. Omeprazole prevents gastric acid secretion in horses, thus rendering it an effective treatment for ulcers.

Omeprazole and other drugs known as proton pump inhibitors are used to treat acid-related conditions in humans. When given to humans, reduced gastric acid production is associated with a decline in the digestibility of several nutrients, including protein, fat, calcium, iron, and vitamin B12.

In horses, however, the effect of omeprazole on nutrient digestibility was unknown.

A study was therefore designed to determine the effect of short-term administration of omeprazole on the digestibility of several nutrients.

Researchers found that omeprazole did not affect the digestibility of dry matter, crude protein, fat, acid detergent fiber, neutral detergent fiber, starch, or water-soluble carbohydrates. Omeprazole did not change the digestibility of any mineral except calcium. Calcium digestibility decreased by as much as 20% in horses given omeprazole.

Adding Perspective for Horse Owners

Because of its efficacy in healing gastric ulcers, omeprazole is commonly prescribed to horses. When given at the recommended dose of 4 mg/kg, omeprazole is intended to be used for 28 days. What should horse owners do to ensure optimal calcium digestibility when treating their horses with omeprazole?

First, take a close look at the horse’s total diet. If horses are being fed a fortified feed at the rate recommended by the manufacturer and good-quality hay or pasture, especially if there is alfalfa or clover in the mix, the amount of calcium consumed is likely adequate and no change in the diet is necessary.

If, on the flip side, a fortified feed is not fed or is blended with a cereal grain, such as oats, and a grass hay is offered, adjustments to the diet may be necessary to ensure optimal calcium status. A horse on this diet might need an additional 10 g, or one-third ounce, of calcium per day.

How can horse owners supply additional calcium?

An easy way to add calcium is through the addition of good-quality alfalfa hay. As little as two pounds of alfalfa (as long-stem hay, cubes, or pellets) will provide 15 g of calcium.

Alternatively, calcium can be supplied through the use of a research-proven supplement, such as Triacton from Kentucky Equine Research. With 12% highly digestible calcium, the recommended serving of Triacton will meet any calcium shortfall created by omeprazole. In addition to supplying calcium, the benefits of Triacton are threefold: increases bone density, provides a stomach buffer, and minimizes the acidity of the hindgut.

Unsure if your horse is receiving optimal nutrition? Load your horse’s diet into MicroSteed and have a look for yourself, or communicate one-on-one with a Kentucky Equine Research nutrition advisor.