The effects of medetomidine and its reversal with atipamezole on plasma glucose, cortisol and noradrenaline in cattle and sheep

In the present study, we report the effect of medetomidine followed by atip amezole on plasma glucose, cortisol and noradrenaline in calves, cows and s heep. Eight calves, eight lactating dairy cows and eight adult female sheep were included in a crossover trial. The animals were injected i.v. with me detomidine (40 mug/kg), followed 60 min later by atipamezole i.v. (200 mug/ kg) or saline. The wash-out period between experiments was 1 or 2 weeks. I n every animal, medetomidine induced a marked hyperglycaemia, which was rev ersed by atipamezole. Cortisol levels increased significantly in cows and s heep, reaching levers 4-8-fold higher than the baseline levels 25-45 min af ter injection of medetomidine, Atipamezole did not affect the cortisol leve ls, except in sheep where an increase was observed. Plasma levers of noradr enaline decreased in cows and sheep after medetomidine injection, reflectin g the inhibition of sympathetic activity by the drug. After injection of th e antagonist, there was a large increase in noradrenaline revels. In conclu sion, a high dose of medetomidine does not seem to reduce the overall endoc rine stress response in cattle and sheep, which has previously been reporte d in other species.