Tissue concentrations of sulfamethazine and tetracycline hydrochloride of swine (Sus scrofa domestica) as it relates to withdrawal methods for international export.

The use of water medications is a common practice in the US swine industry to treat and prevent infections in swine herds with minimal labor and without risk of needle breakage. There are concerns that FDA-approved withdrawal times (WDT) may be inadequate for several water medications when exporting pork products to countries where MRLs (maximum residue limits) are lower than US tolerance levels. In this study, withdrawal intervals (WDI) were estimated for pigs when dosed with tetracycline and sulfamethazine in water.