ARS | Publication request: Development and model testing of anti-mortem screening methodology to predict prescribed drug withholds in heifers

Submitted to: International Association for Food Protection Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 6, 2012
Publication Date: July 25, 2012
Citation: Salter, R., Jones, S., Goldsmith, T., Quintana, J., Rapnicki, P., Shuck, K., Wells, J., Griffin, D. 2012. Development and model testing of anti-mortem screening methodology to predict prescribed drug withholds in heifers. In: Proceedings of International Association for Food Protection, July 22-25, 2012, Providence, Rhode Island. Poster P3-13.

Technical Abstract: Introduction: A simple, cow-side test for the presence of drug residues in live animal fluids would provide useful information for tissue drug residue avoidance programs. Live animal tests have the potential to allow verification that an individual animal is free of drug residues before sale for human consumption. Purpose: Adapt the Kidney Inhibition Swab (KIS) test to detect antibiotics in live animal fluids, urine and serum. Determine the fluids’ ability to predict the withhold time of sulfadimethoxine (SDM). Materials and Methods: Feed-lot-heifers were treated with intravenously at 55mgSDM/kg. Initially 3 animals were dosed. Urine was collected daily for 5 days. Blood, spun down to serum, and saliva were collected pre, day 1 and 4 post-treatment. In the 2nd dosing 12 treated animals had urine and serum collected daily for 6 days. Samples were tested by liquid chromatography and with KIS-modification (Charm Sciences, Inc.). Results: In 1st dosing, both urine and serum samples at 24 hours were KIS positive. With day 2 and 3 urine samples 1 of 3 cows were positive. The 4th day urine samples were negative, while 2 of 3 serum samples were positive. HPLC indicated the presence of parent compound in serum and the presence of parent and metabolite in urine. Saliva sampling and testing was too variable. In the 2nd dosing experiment the urine samples were 80% KIS positive on days 1 and <5% positive on days 2, 3 and 4. Serum samples were 100% positive on days 1 and 2; 75% positive on day 3; 67% positive on day 4; 50% positive on day 5 and 30% positive on day 6. Significance: The recommended withhold time of SDM is 5 days post-treatment. Serum tests were more predictive than urine in detecting treated animals. Other drug studies are needed to determine if this relationship is unique to the drug used. Understanding incurred-drug-residue relationships between tissue, urine and serum samples are important to acting upon screening results.