Monitoring of illicit corticosteroid use in beef cattle by using a histological-analytical approach.

Introduction - Dexamethasone (DEX), betamethasone (BETA) and prednisolone (PREDN) are synthetic corticosteroids authorized in cattle breeding for the treatment of metabolic disorders and inflammatory diseases but they are illegally used, at lower doses as growth promoters, to improve productive performances. To safeguard the health of the consumer, the EU (Directive 2008/97 /EC) has banned this practice(1). Aim - During 2007, a surveillance plan was conducted in several slaughterhouses of the Veneto Region and 300 cattle were monitored for the presence of illicit treatments with corticosteroids. Materials and methods - Liver, thymus and urine from bladder, were collect to detect, through chemical and histological examination, the presence of corticosteroids treatment. Based on the results of the histological analyses on thymus samples, the animals were classified into 23 Suspected/Doubts and 16 Negative. Liver and urine samples were analyze for the presence of residues of corticosteroids by a multi-residue method in liquid chromatography coupled with mass spectrometry (LC-MS/MS), able to identify and quantify the presence of DEX, BETA and PREDN. Results - The confirmatory method adopted, revealed DEX presence in 11 samples of bovine liver, 10 from the group "suspect" by histological examination and only one sample from the group of negative ones. In 6 liver samples DEX concentrations were above MRL (2 ng/g) and 4 urine samples collected from the same animals revealed DEX detectable concentrations. From published data on DEX elimination rate and from liver and urine results of the monitoring plan, it can be stated that the treatment with DEX in positive animals continued until a few days before slaughtering. Conclusions - The histological examination can be used as first screening of animals illegally treated with DEX. The results obtained confirm the risk for the consumer of foodstuffs of animal origin from cattle, treated with corticosteroids until slaughtering time.