Sulphadimidine (or sulfamethazine) is a widely used, water-soluble sulfonamide antibiotic in veterinary medicine, active against gram-positive and gram-negative bacteria (e.g., Salmonella
Pasteurella
E. coli
. It treats respiratory, gastro-intestinal, and coccidiosis infections in animals
. Acting by inhibiting bacterial folic acid synthesis, it is often given as an injection