Effects of azaperone and acetylpromazine on social and environmental behaviour in sheep

1 Acetylpromazine (Acp, 0.05, 0.1 and 0.5 mg/kg) and azaperone (Azp, 1.0, 1.25 and 1.5 mg/kg) were given by intramuscular injection to separate groups of seven familiar Romney ewes. Thirty minutes after injection the sheep were led into a featureless arena and spatial distribution, activity and shade preference were monitored for 20 min by overhead photography. 2 Behavioural response was complex with both stimulant and depressant effects being seen. The response trends with increasing time for all three measures were significantly different for the two drugs. In particular, Azp tended to increase animal dispersion and Acp to decrease it, in agreement with earlier predictions. 3 The dosage range for Azp was adequate for reduction of individual movement and inter-animal distance but steady state effect was not reached in the time period studied. All doses of Azp initially caused disorientation, as measured by shade preference,, but this improved as sedation deepened. 4 The highest dose of Acp (0.5 mg/kg) achieved steady state effect on individual movement within the study period. The three doses of ACp caused either no change or a slight increase in inter-animal distance. Disorientation with Acp was less and briefer than that seen with Azp.