Open-field behaviour in sheep following treatment with the neuroleptics azaperone and acetylpromazine.

The behavior of individual Romney ewes in an open field was observed after intramuscular injection of isotonic saline or two doses of azaperone (0.5, 1.0 mg/kg) or acetylpromazine (0.1, 0.25 mg/kg). Azaperone significantly reduced the distance travelled, urination, and the time spent walking. However it increased nosing of the walls and floor (investigation). Azaperone also increased the numbers of sheep seen grazing and pawing and decreased the number heart vocalizing at least once. The only effect acetylpromazine had was to reduce the number of sheep heart vocalizing. The main results were interpreted as supporting a superior reduction of emotional behaviour by azaperone. It was therefore suggested that, as with pigs, azaperone might be useful for treating stress in sheep.