Natural and synthetic corticosteroids are widely used in veterinary medicine for their anti-inflammatory properties, but are also illegally used in animal breeding as growth-promoting agents: this latter application in livestock production has been banned within the European Union due to health concerns for the consumer. In this work urine samples collected from bovines experimentally treated with dexamethasone (0.4 mg of dexamethasone 21-disodium phosphate per capita/day for 20 consecutive days) and bovines bred under strictly controlled conditions were investigated for the presence of natural and synthetic corticosteroids, using a simple multi-residue liquid chromatography-tandem mass spectrometry method, developed and validated in accordance with the criteria of the Commission Decision 2002/657/EC. The aim of this work is to investigate the effect of a low dosage and long term dexamethasone treatment on the levels of endogenous corticosteroids in cattle and to evaluate the possible presence of prednisolone residues in bovines bred under strictly controlled conditions. Our findings confirm the high and rapid rate of dexamethasone urinary excretion. Dexamethasone treatment elicited an early reduction of hydrocortisone and cortisone, suggesting the disappearance of these two hormones as an indirect indicator of corticosteroid treatment in cattle. Prednisolone residues were found (concentration interval 0.4-1.4 ngmL(-1)) in urine samples collected from control bovines especially at the slaughterhouse, together with high levels of hydrocortisone and cortisone. Further studies are necessary to find out the reason of unexplained excretion of this hormone in urine samples of untreated bovines.
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