McMeekan C M, Mellor D J, Stafford K J, Bruce R A, Ward R N, Gregory N G
Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
Aust Vet J. 1998 Apr;76(4):281-5. doi: 10.1111/j.1751-0813.1998.tb10160.x.
To determine the effect of a long-acting local anaesthetic on the plasma cortisol response in calves dehorned using a scoop.
A physiological study with controls.
Seventy female calves, 3 to 4 months old, were divided into seven groups and dehorned by scoop with or without a long acting local anaesthetic (bupivacaine) which provides local anaesthesia for 3 to 4 h. In some treatment groups the local anaesthetic was given a second time, after 4 h, to give 8 h of anaesthesia. Blood samples were taken before and for 9 h after treatment and plasma cortisol concentrations were measured.
Scoop dehorning caused a marked rise in plasma cortisol concentration, which returned to pre-dehorning values after 7 h. The cortisol concentrations of calves given bupivacaine were similar to those of control animals for 4 h after dehorning, but then a significant and protracted rise occurred, with concentrations returning to pretreatment values at about 9 h after dehorning. In calves given a second treatment of bupivacaine 4 h after dehorning, the plasma cortisol concentration remained similar to control values for 8 h after dehorning but then increased sharply.
During its period of activity long-acting local anaesthetic prevented the rise usually seen after scoop dehorning in plasma cortisol concentrations; by inference it also alleviated the pain-induced distress caused by this procedure. However, when its effects had worn off the plasma cortisol values rose sharply indicating that animals still experienced pain-induced distress despite local anaesthetic being administered.
确定长效局部麻醉剂对使用铲子去角犊牛血浆皮质醇反应的影响。
一项设有对照的生理学研究。
将70头3至4月龄的雌性犊牛分为7组，使用或不使用长效局部麻醉剂（布比卡因，可提供3至4小时的局部麻醉）通过铲子去角。在一些治疗组中，4小时后再次给予局部麻醉剂，以提供8小时的麻醉。在治疗前及治疗后9小时采集血样，测定血浆皮质醇浓度。
用铲子去角导致血浆皮质醇浓度显著升高，7小时后恢复到去角前的值。去角后4小时内，给予布比卡因的犊牛的皮质醇浓度与对照动物相似，但随后出现显著且持续的升高，去角后约9小时浓度恢复到治疗前的值。在去角后4小时接受第二次布比卡因治疗的犊牛中，去角后8小时血浆皮质醇浓度仍与对照值相似，但随后急剧升高。
在其作用期间，长效局部麻醉剂可防止通常在使用铲子去角后出现的血浆皮质醇浓度升高；由此推断，它也减轻了该操作引起的疼痛性应激。然而，当它的作用消失后，血浆皮质醇值急剧上升，表明尽管使用了局部麻醉剂，动物仍经历疼痛性应激。
