Median effective dose of propofol required for induction of anaesthesia in goats.

OBJECTIVE: To determine the median effective dose (ED50) of propofol required for induction of anesthesia in goats and the frequency of myoclonic activity and apnea associated with propofol administration. DESIGN: Clinical trial. ANIMALS: 28 healthy mature goats. PROCEDURE: ED50 was determined by use of the up-and-down method. The first goat was given 4 mg of propofol/kg (1.8 mg/lb) of body weight, i.v. Dose was increased by 25% for the next goat if endotracheal intubation was not possible and decreased by 20% if it was. For each subsequent goat, dose was determined on the basis of response of the previous goat. The ED50 was calculated by use of probit analysis. Induction time, frequency and duration of apnea, frequency of myoclonus, and other adverse effects were recorded. RESULTS: ED50 was determined to be 5.1 mg/kg (2.3 mg/lb). Mean (+/- SD) induction time was 23.2 +/- 4.7 seconds. Apnea was observed in 27 of 28 goats; mean (+/- SD) duration of apnea was 72.9 +/- 38.3 seconds. dose did not correlate without duration of apnea. Myoclonic activity was observed in 16 of 28 goats; frequency of myoclonus was not associated with dose. Cyanosis, regurgitation, and signs of pain during injection were not observed. CLINICAL IMPLICATIONS: Administration of propofol at 5.1 mg/kg (2.3 mg/lb), i.v., should permit endotracheal intubation in half of unpremedicated, healthy, mature goats. Myoclonus and apnea were associated with propofol administration.