|Newman, David - North Dakota State University|
|Larsen, Steven - National Pork Board|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/15/2013
Publication Date: 9/9/2013
Citation: Smith, D.J., Lupton, S.J., Shelver, W.L., Newman, D.J., Larsen, S. 2013. Depletion of penicillin G residues in sows after intramuscular injection. Meeting Proceedings. SafePork 2013 Proceedings Book. 2013, Pg 39-41..
Interpretive Summary: Pencillin G procaine is an antibiotic that is often used at very large doses to prevent infection in injured or sick sows that are nearing the end of their productive lives. Although the antibiotic was approved several decades ago for use hogs, it was approved for use in market hogs at modest doses, not for use in very large sows. Nevertheless, the off-label use of penicillin G procaine is allowed under the auspices of the Animal Drug Use Clarification Act as long as an adequate pre-slaughter withdrawal period is observed. This study was conducted to determine what an adequate withdrawal period is for heavy sows treated with penicillin G procaine. We learned that the proper pre-slaughter withdrawal period is greater than 40 days if kidneys are used as the tissue of interest. However, residues in skeletal muscle are completely depleted 15 days after the administration of penicillin. Therefore we are recommending that sows treated with penicillin G procaine be slaughtered 15 days after their last treatment day and that kidneys not be used for human food in treated animals.
Technical Abstract: A penicillin G procaine residue depletion study was conducted in heavy sows to estimate the pre-slaughter withdrawal periods necessary to clear penicillin from kidney and muscle. Heavy sows (n = 126) were treated with penicillin G procaine at a 5x dose (33,000 IU/kg) for 3 consecutive days by intramuscular (IM) injection using 3 separate patterns of drug administration. Treatments differed by pattern and volume of penicillin G procaine administration. Sets of 6 animals per treatment were each slaughtered with 5, 10, 15, 20, 25, 32, and 39 day withdrawal periods; skeletal muscle and kidney were collected for penicillin G analysis by LC-MS/MS. Penicillin residues in skeletal muscle averaged 23.5 +/- 10.5 ng/g at withdrawal day 5 for all treatments, but averaged 3,760 +/- 1,930 ppb in kidney. By 15 days of withdrawal, skeletal muscle penicillin G residues were quantifiable in only one of 18 (5.5%) treated hogs (3.4 ng/g) but were easily detected in kidneys of 50% of the treated hogs, with kidney residues in all hogs averaging 119 +/- 199 ng/g (mean includes 8 non-detects counted at 1/2 the limit of detection). Using an action limit of 25 ng/g and a ln-linear depletion model, the withdrawal period required for penicillin depletion in muscle was 13 days, whereas a 52-day withdrawal period was required for kidney. The FARAD recommended withdrawal period of 15 days for hogs treated with extra-label doses of penicillin is adequate for skeletal muscle, but is inadequate for kidney. Slaughter of penicillin treated hogs after a 15-day withdrawal period, with kidney discard into inedible offal would ensure the human food safety of skeletal muscle.