Behavioural and pituitary-adrenal characteristics of pigs differing by their susceptibility to the malignant hyperthermia syndrome induced by halothane anesthesia. 1. Behavioural measures.

Behavioural responses were compared in Pietrain pigs and in Large White pigs differing by their susceptibility to the malignant hyperthermia syndrome induced by halothane. Non reactive Pietran pigs (P--) displayed a higher level of locomotor activity in a new environment than either reactive Pietrain pigs (P+) or Large White pigs. Pietran pigs performed better in a latent learning proceudre (latency of approach or feeding response, after exploration of the new environment) and in a continuound P-- did not reach significance, but P+ pigs tended to be superior to P-- animals. The three groups did not differ on a measure of passive avoidance. These results suggest that Large White pigs are characterized by a lower ability to initiate active responding when confronted with aversive events. The same would be true when Pietrain positive pigs are compared with Pietrain negative pigs, although to a lesser extent.