Study: Ophthalmic Atropine Use May Increase Risk Of Colic Sponsored by: Atropine is a commonly used drug in horses with eye issues – specifically with equine uveitis – but a new study has found that it can affect more than just the equine eye: it can also increase a horse's risk of colic. Dr. Lena Ström and her research team investigated how the drug interacts with the horse's body and found that frequent administration of atropine may reduce intestinal action, increasing colic risk. The team suggests allowing for additional time between atropine treatments to minimize colic risk, but the frequency of medication administration must focus on the horse's comfort.