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

Abstract

In the present study, we report the effect of medetomidine followed by atipamezole on plasma glucose, cortisol and noradrenaline in calves, cows and sheep. Eight calves, eight lactating dairy cows and eight adult female sheep were included in a crossover trial. The animals were injected i.v. with medetomidine (40 microg/kg), followed 60 min later by atipamezole i.v. (200 microg/kg) or saline. The wash-out period between experiments was 1 or 2 weeks. In every animal, medetomidine induced a marked hyperglycaemia, which was reversed by atipamezole. Cortisol levels increased significantly in cows and sheep, reaching levels 4-8-fold higher than the baseline levels 25-45 min after injection of medetomidine. Atipamezole did not affect the cortisol levels, except in sheep where an increase was observed. Plasma levels of noradrenaline decreased in cows and sheep after medetomidine injection, reflecting the inhibition of sympathetic activity by the drug. After injection of the antagonist, there was a large increase in noradrenaline levels. In conclusion, a high dose of medetomidine does not seem to reduce the overall endocrine stress response in cattle and sheep, which has previously been reported in other species.

A Double-Blinded, Randomized Comparison of Medetomidine-Tiletamine-Zolazepam and Dexmedetomidine-Tiletamine-Zolazepam Anesthesia in Free-Ranging Brown Bears (Ursus Arctos)

“…On the other hand, it is well documented that the use of alpha-2 adrenoceptor agonists increases plasma glucose concentrations through insulin release inhibition [26, 48]. The role of alpha-2 adrenoceptor agonists on cortisol concentrations is controversial, and varies among species [26, 27, 48–53]. Additionally, these studies suggest that the drug effect might be age and dose-dependent.…”

“…Medetomidine has been shown to cause greater increases in serum glucose concentration than D [25]. Although the effects of alpha-2 adrenoceptor agonists on cortisol concentrations are controversial [26, 27], we hypothesized that serum concentrations of cortisol, as an indicator of stress, would be less with DTZ.…”

Organochlorines Affect the Steroid Hormone Cortisol in Free-Ranging Polar Bears (Ursus maritimus) at Svalbard, Norway

“…Various studies in different species have reported baseline plasma cortisol levels below 50 ng/ml (Van Lier et al, 1998;Cleary et al, 2000;Dobson & Smith, 2000;Ranheim et al, 2000;Suzuki et al, 2002). Data quantifying baseline plasma cortisol levels of freeranging polar bears are limited.…”

Pituitary Pars Intermedia Dysfunction (Equine Cushing's Disease) in an Onager (Equus hemionus onager)

“…However, it was determined later that although a 2 -agonists such as detomidine and medetomidine cause stimulation of the hypothalamicadrenocortical axis in dogs, cattle, sheep, and other species; in horses, detomidine directly reduces sympatho-adrenal activity and cortisol secretion is unaffected. 1,13,21,22 Thus, its use should have no effect on results of a positive dexamethasone suppression test in domestic horses. In view of the confirmed diagnosis of PPID in Case 1, the authors have concluded that there is sufficient similarity in the hypothalamic-adrenocortical axis of onagers and domestic horses to assume that the dexamethasone suppression test was a reliable diagnostic test for PPID in this case.…”

“…Other differential diagnoses for hyperglycemia included stress, use of a 2 -adrenoreceptor agonists in the anesthetic premedication and diabetes mellitus. 22 The suspicion of PPID drew attention to additional clinical signs present in the onager. These included a bulging of the supra-orbital fat pads and a thick curly hair coat, particularly over the neck region (Fig.…”