Corid 20% Soluble Powder is an amprolium-based coccidiostat packaged as a dry, water-soluble powder for use in cattle. The powder dissolves into fresh drinking water to form a stock solution, or it can be mixed into a smaller volume of water and given as an oral drench with a dose syringe. Amprolium works by interfering with the ability of coccidia to use thiamine, limiting the parasite at an early stage of its life cycle in the small intestine. Dosing follows one of two label protocols, a shorter high-dose course for active outbreaks or a longer lower-dose course for periods of expected exposure, with the solution offered as the sole water source for the duration of the course. Treatment is intended to be applied on a group, pen, or herd basis rather than to individual animals. The pouch should be stored in a cool, dry location out of high humidity, and any mixed stock solution should be kept in a clean, closed, labeled container. A pre-slaughter withdrawal period applies, and label directions should be followed closely when treating calves.