Verification of compliance with organic meat production standards by detection of permitted and nonpermitted uses of veterinary medicines (tetracycline antibiotics).

In the production of "organic" meat, one of the controlled processes is the use of veterinary drugs. Strict standards are in place as to when and how such drugs may be used. Therefore, the aim of this project was to determine whether it was possible to distinguish between a single therapeutic dose of a tetracycline (permitted under the standards) and both multiple therapeutic dosing and prophylactic dosing (not permitted). This comprised an evaluation of (i) pigs that were treated with oxytetracycline and (ii) chickens dosed with two different tetracycline antibiotics (oxytetracycline and chlortetracycline). The methodology described, using bone sectioning and examination under ultraviolet illumination (either direct observation or fluorescent microscopy), allows samples from animals that have been treated with different dosing regimes (a single therapeutic dose, two successive therapeutic doses, and long-term, low-level "prophylactic" dosing) to be assessed for compliance with organic farming regulations. Validation of the methodology by blind checks of unknown samples by a second operator has been successfully performed, and validation results are presented. The developed methodology has been shown to be applicable to a variety of species and a selection of tetracycline drugs.