The cardiorespiratory effects of diazepam-ketamine and xylazine-ketamine anesthetic combinations in sheep.

: The cardiorespiratory dynamics and anesthetic effects of intravenously administered diazepam-ketamine (0.375 mg kg-1/7.5 mg kg-1) and xylazine-ketamine (0.1 mg kg-1/7.5 mg kg-1) were investigated in six domestic sheep (Ovis aries). The depth of analgesia and sedation was evaluated and the effects of the anesthetic drug combinations on hemodynamics and pulmonary mechanics were monitored before, and up to 90 minutes after, drug administration. Diazepam-ketamine and xylazine-ketamine induced effective anesthesia for periods lasting 15 minutes and 25 minutes, respectively. Both drug combinations caused transient respiratory acidosis. However, no profound effects on respiration or pulmonary function were observed. Neither anesthetic regimen caused significant effects on heart rate or pulmonary hemodynamics, but they caused significant decreases in cardiac output. Xylazine-ketamine resulted in a significant decrease in mean systemic arterial blood pressure (Psa) with a concurrent decrease in systemic vascular resistance (SVR). Diazepam-ketamine caused a significant increase in SVR without affecting Psa. Xylazine-ketamine may be contraindicated in animals with compromised heart function because of its hypotensive effects. Otherwise, both drug combinations, in the doses used, can provide short-term anesthesia suitable for minor surgical procedures and painful experimental maneuvers.