Vocalization and physiological response of pigs during castration with or without a local anesthetic.

The objectives of this project were to see whether heart rate, respiration rate, blood pressure, and vocalization could be used to evaluate stress of castration in pigs. Six groups of pigs 1, 2, 4, 8, 16, and 24 d of age were used in the study, a total of 172 pigs. Half of each group of pigs received lidocaine before castration, injected subcutaneously over the testicle and infiltrated around the cord; the other half were left as controls. Pigs castrated without lidocaine had a higher heart rate (P < .02) and higher frequency of highest energy (HEF) measurements of vocalization (P < .05). Incising the scrotum and severing the spermatic cord elicited the greater heart rate response (P < .05) to castration without anesthetic, whereas HEF was lower during cutting of the cord. Both the heart rate and HEF data suggest that castration without anesthetic is of greater stress for pigs 8 d of age or older. Respiration rate was not a viable measure of stress associated with castration.