Degree Type


Date of Award


Degree Name

Master of Science


Veterinary Diagnostic and Production Animal Medicine


Veterinary Preventive Medicine

First Advisor

Locke A. Karriker


Beta-lactam antimicrobials have historically been used as a treatment for illness in sows. In 2011 the FSIS updated its residue screening technologies, resulting in an increase of penicillin G residues in cull sows at slaughter. Little information is available concerning tissue residue depletion of procaine penicillin G or ampicillin trihydrate in sows.

Original research was performed to characterize the tissue residue depletion profiles and calculate withdrawal periods of procaine penicillin G and ampicillin trihydrate in sows using LC-MS/MS analysis. Penicillin G residues persist in kidneys, skeletal muscle, and injection sites for extended periods following treatment. The residues persist longer at higher doses, and a withdrawal period of 30 days is needed to ensure penicillin residue depletion in the kidney at 15,000 IU/lb IM SID for three consecutive days. There is no evidence for environmental transfer of penicillin G residues from treated sows to untreated sows. Ampicillin trihydrate is metabolized quickly by the sow, with residues only detected in the kidney at one day following treatment. Residues persisted at high concentrations at the injection sites for 40 days following treatment at the conclusion of the study. Injection site withdrawal times were estimated at 89 days for a 12 mg/kg IM SID dose for three consecutive days. Urine and plasma are potential ante-mortem screening matrices for penicillin G or ampicillin. Environmental samples and oral fluids are not good samples for beta-lactam residue analysis. Charm MRL™ test kits are a fairly sensitive and specific urine screening method for residue detection in urine.

Further research is needed to determine withdrawal times of ampicillin trihydrate in sows in edible tissues, and to evaluate the efficacy of alternative screening methods. Available research describes a metabolism of procaine penicillin G and ampicillin trihydrate based on absorption, which is rapid once drug enters circulation. Original research supports this, but shows an extended residue of both drugs at injection sites following treatment. This information may be applied to establish recommendations for withdrawal times on extra-label beta-lactams and used clinically as a guide for the protection of meat from violative residues entering the consumer supply.


Copyright Owner

Christine Ellen Mainquist-Whigham



File Format


File Size

104 pages