Sulfadimethoxine is a sulfonamide antibiotic used primarily in veterinary medicine to treat bacterial and protozoal infections in livestock and poultry, including respiratory and intestinal infections in cattle, swine, and birds, as well as coccidiosis (a protozoal disease) in poultry. It is effective against a range of gram-positive and gram-negative bacteria and certain protozoa. Commonly administered in feed, water, or injectable forms, it is used for treatment and as a preventive measure during periods of stress or disease outbreaks. It is also employed in aquaculture to manage bacterial diseases in fish. Its long-acting nature, due to a prolonged half-life, allows for less frequent dosing, making it practical for large-scale farming operations.