Clinico-physiological and haemodynamic effects of butorphanol-midazolam and butorphanol-diazepam premedication during thiopentone-isoflurane anaesthesia in bovine

The study was conducted in 14 bovines of either sex, aged 1–12 yr and weighing 100–400 kg to evaluate and compare the clinico-physiological and haemodynamic effects of butorphanol-midazolam and butorphanol-diazepam premedication in thiopentone induced and isoflurane maintained anaesthesia in bovines. The animals were randomly divided into two groups having seven animals each. Premedication was carried out with butorphanol (0.02 mg/kg b.wt)-midazolam (0.2 mg/kg b.wt) and butorphanol (0.02 mg/kg b.wt)-diazepam (0.2 mg/kg b.wt) combination in groups I and II, respectively, followed by 5% thiopentone sodium for anaesthetic induction and isoflurane for maintenance in both groups. Clinical observations revealed excellent sedation and moderate level of muscle relaxation in group II animals as compared to group I after premedication. Butorphanol-diazepam premedication reduced 15% induction dose of thiopentone as compared to butorphanol-midazolam premedication. Thiopentone produced smooth and excitement free induction while isoflurane was found to be excellent for maintenance; and after its discontinuation, quick and uncomplicated recovery was observed in both groups. A significant reduction in respiration in group I animals was recorded while heart rate was initially increased followed by decrease in both groups. Rectal temperature showed gradual but insignificant decline in both groups. Systolic, diastolic and mean arterial pressures were also significantly reduced in both groups. It was observed that butorphanol-diazepam premedication provided better sedation, adequate muscle relaxation, reduced the induction dose of thiopentone and produced satisfactory clinical, physiological and haemodynamic stability during general anaesthesia in bovines.