Omeprazole is the gold star treatment for equine ulcers, but what are the long term effects of omeprazole on horses? When our horses are sick, we want nothing more than to help them get better. We choose to treat with omeprazole because of its ability to heal ulcers, alleviate pain, and protect against further lesions. Like every medication, omeprazole has long term effects. As horse owners and caregivers, it is important to understand how treatment may effect the horse in the future.
Bone Density
Studies involving both humans and experimental animals show that using omeprazole for more than one year can lead to decreased bone density. Omeprazole inhibits the absorption of dietary calcium in the small intestine, thus, decreased bone density. A decrease in bone density puts the user at a higher risk for bone fractures. Although a longitudinal study has not been completed, results from studies with shorter durations show promising results for our equine partners. Calcium blood levels were found to not be significantly lower in horses who were given omeprazole for 60 days when compared to horses given a placebo. Additional studies have been completed showing that calcium levels were unchanged among numerous horses given differing dosages of omeprazole. Therefore, it can be extrapolated from current data that horses do not suffer the same effects to bone density as found in humans and experimental animals.
Food and Nutrient Absorption
Another common question is whether omeprazole will affect food and nutrient absorption, leading to imbalances and creating additional problems. The more pertinent question we should be asking is how ulcers are affecting food and nutrient absorption. Studies have found that an increase in acidity in the duodenum, elevated PH in digestive juices, and decreased activity of pancreatic enzymes are all associated with equine ulcers. These changes cause the absorption of fats to be compromised. When treated with omeprazole, horses are found to have increased lipid (fat) absorption. Therefore, treating your horse with omeprazole actually helps absorption, rather than hinder.

We all want what is best for our horses. The last thing we want is to treat one problem only to be presented with another. Fortunately, current research shows that long term effects of omeprazole on horses are limited, making it preferred choice for ulcer treatment.