Electroimmobilization and ovine plasma cortisol concentrations: effect of current intensity, current duration and...

Whether the increases in plasma cortisol concentrations which are associated with electroimmobilization (E-IM) of conscious sheep are modified by current intensity, current duration or prior treatment with diazepam was assessed. Sheep were electroimmobilized at 30, 40 or 60 mA for one minute and at 40 mA for two or four minutes. After E-IM of one minute's duration, peak plasma cortisol concentrations occurred at 20 minutes and were 39.1 +/- 7.8 ng ml-1 at 0 mA (control), 56.7 +/- 9.6 ng ml-1 at 30 mA, 62.1 +/- 6.9 ng ml-1 at 40 mA and 78.4 +/- 3.2 ng ml-1 at 60 mA. Both the peak plasma cortisol concentrations and the integrated cortisol responses to E-Im were correlated with current intensity (P less than 0.01). The cortisol responses to E-Im at 40 mA for one, two and four minutes were not significantly different and the response to E-IM at 40 mA for one minute was not affected by the administration of diazepam (0.2 mg kg-1 intravenously) 15 minutes before E-IM. These results indicate that the cortisol response to E-IM is directly dependent on current intensity and that adrenocortical activation by E-IM may be minimised by choosing the lowest current at which effective restraint is maintained.