#09-256

Complete

Date Full Report Received

06/26/2012

Date Abstract Report Received

06/26/2012

Investigation

Institution:
Primary Investigator:

The objective of this project was to determine whether pigs exposed to water medications can result in stomach tissue levels that exceed safety levels and thus affect export of pork products to countries with safe levels significantly different and set at concentration levels lower than in the US. Commercial sulfamethazine and tetracycline mediations were given to weanling and slaughter weight pigs to determine whether the pig contained the drug at specific withdrawal times for these two drugs. Data from these studies suggest that in spite of the known low bioavailability of these drugs that drug residue levels can persist in several pork tissues as well as stomach tissues for many days beyond the US label withdrawal time for the drug. This is the first report of stomach tissue as the target tissue for tetracycline. These findings are critically important for US export of pork products where the tolerance levels in foreign countries are significantly lower than those in the US. This report provides recommendations based on our experimental findings that will assist swine veterinarians and pork producers in planning treatment protocols and extending withdrawal times for tetracycline and sulfamethazine when used as water additives at the approved label dose.