A field survey on the presence of prednisolone and prednisone in urine samples from untreated cows

Prednisolone is a synthetic glucocorticoid widely employed in bovine clinical practice that may also be used illegally as a growth promoter. Recent in vitro and in vivo studies lend support to the hypothesis that prednisolone could be synthesised from cortisol in untreated cattle subjected to stressful events. To verify such a hypothesis, a field survey was conducted on urine samples collected from 131 guaranteed untreated cows and analysed for the presence of prednisolone and prednisone – in some instances also for cortisol and cortisone – with a validated LC/MS-MS method. None of the examined samples exhibited either prednisolone levels higher than the CCα limit (around 0.70 µg l−1) or prednisone, being therefore officially compliant for both analytes. Trace amounts of prednisolone, approximately estimated in the range 0.1–0.3 µg l−1 were found in only seven samples from cows also showing urinary cortisol and cortisone levels higher than those detected in negative specimens, as the result of a probable stress condition.