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Investigation into sources of contamination of cattle with phenylbutazone
  1. Terence L. Fodey, PhD,
  2. Wesley G. Smyth, HNC Chemistry,
  3. Paul Barnes, HNC Horticulture,
  4. Imelda M. Traynor, HNC Applied Biology,
  5. D. Glenn Kennedy, PhD and
  6. Steven R. H. Crooks, PhD
  1. Veterinary Sciences Division, Agri-Food and Biosciences Institute, Stoney Road, Belfast BT4 3SD, UK
  1. E-mail for Correspondence: terence.fodey{at}

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PHENYLBUTAZONE (PBZ), also known as ‘bute’, is a NSAID authorised to treat horses suffering from musculoskeletal disorders such as rheumatoid and arthritic diseases and to relieve them from the associated pain.

An assessment of PBZ by The Committee for Medicinal Products for Veterinary Use (CVMP) (European Medicines Agency 1997) found that the main health risks to the consumer were blood dyscrasias and the genotoxic/carcinogenic potential for which no thresholds could be identified and so no maximum residue limits could be established. As a consequence of this assessment, PBZ is not permitted for use in any animal destined for the food chain. The risks were reconfirmed more recently in a joint statement by the European Food Safety Authority and European Medicines Agency (2013). In addition to the EU, PBZ is banned from use in food production animals in most other countries, including the USA, Canada and Japan.

There is potential for unauthorised use of the drug in beef or dairy cattle and small numbers of cattle have tested positive for the drug over the past decade as part of the European monitoring of veterinary medicinal product residues and other substances in live animals and animal products. The most recent report from The European Food Safety Authority (2014), presenting results for all veterinary drug residues found in 2012, indicates that 0.1 per cent of the cattle tested in the UK were found to contain detectable concentrations of the drug. There is also anecdotal evidence that animals which have not been treated with the drug but have been present on a farm when another animal has been treated have also displayed levels of the drug. This study was designed to determine how and if contamination of cattle with PBZ could occur. The routes of contamination investigated were (i) from a feeding …

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  • Provenance: Not commissioned; externally peer reviewed

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