INTRODUCTION To get more insight into the relationship between stress and the possible ‘endogenous’ synthesis of prednisolone claimed by some authors (1), the effects of truck transportation and the subsequent slaughtering was assessed in untreated cows by measuring the concentrations of cortisol and cortisone in urines as well as in liver and adrenals from the slaughtered animals. All samples were also analyzed for the presence of prednisone and prednisolone. MATERIALS AND METHODS The study was conducted in 15 untreated cows at the end of their productive cycles reared in different farms. Urines were first collected in living animals at the farm; after some days, animals were transported by truck to the abattoir, slaughtered after a short wait, and further subjected to a second urine sampling directly from the bladder. Specimens of liver and adrenals were also collected. Prednisolone and prednisone were measured essentially as described (2), while cortisol and cortisone were determined with a validated HPLC-MS/MS method. RESULTS Cortisol and cortisone concentrations ranging from non-detectable to less than 3.5 ng ml)1 were found in all but one urine sample collected at farm and none of the specimens contained measurable amounts of prednisone or prednisolone. Truck transportation and slaughtering induced a sharp rise in urinary cortisol and cortisone; only in samples displaying the highest concentrations of both compounds (above 48 ng ml)1) the presence of low prednisolone concentrations (0.60 and 0.57 ng ml)1, respectively) could be detected. One liver sample was found to contain measurable amounts of cortisol. Adrenal specimens exhibited variable levels of either cortisone and cortisol or, in one cow only, prednisone and prednisolone (3.4 and 4.2 ng ml)1, respectively), in that case, the corresponding urines proved negative for both compounds. In line with the results of a previous study on three artificially stressed cows (1), our findings confirm that stressful events such as truck transportation followed by slaughtering cause the urinary levels of cortisol and cortisone to rise up to several fold as compared to those recorded in samples collected at farm. However, only in two out of 15 tested cows such an increase was paralleled by the appearance of trace amounts of prednisolone in the same matrix. The adrenal origin of this glucocorticoid is supported by the recovery of both prednisone and prednisolone in the adrenal gland of a cow. CONCLUSION Data from this study confirm the overall very limited incidence of false urinary non compliances for prednisolone in the cow and support the use of the urinary prednisolone to cortisol or cortisone ratio to discriminate between the pharmacological use or abuse of the drug and its possible link to stressful events.
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