Imodium, or loperamide, can be prescribed for dogs in doses of 2 milligrams at a time, but should not be used for longer than two days, according to PetMD. It is more typically used at the same dosage by humans to treat diarrhea.
Loperamide can be prescribed for dogs to treat malabsorption and maldigestion that result when dogs are not able to properly extract nutrients from the food they eat, states PetMD. Loperamide is a nonaddictive, mild narcotic that works by slowing the passage of food through the dog's digestive tract by relaxing the contraction of the stomach muscles. Slowing the pace of digestion increases the absorption of nutrients and water, which helps treat diarrhea.