Local and General Anesthetic Effects on Behavior and Performance of Two- and Seven-Week-Old Castrated and Uncastrated Piglets

Abstract

Four experiments were conducted to examine the effects of general and local anesthetics given prior to castration on piglet behavior and weight gain. The first experiment showed that use of general anesthesia by xylazine, ketamine hydrochloride and glyceryl guaiacolate for 2-wk-old piglets resulted in the death of 28% of the piglets and, for those that survived, suppressed nursing behavior. In the second experiment, using 2-wk-old piglets, local anesthesia by lidocaine hydrochloride prevented the slight (30 min) castration-induced nursing behavior suppression. In the third and fourth studies, using 7-wk-old pigs, local or general anesthetic did not overcome castration-induced changes in behavior. Castration affected behavior of 7-wk-old pigs for 6 to 8 h. None of the treatments in any of the studies influenced weight gain. We conclude that castration is painful for 2-wk-old and 7-wk-old pigs. The 2-wk-old pig seems behaviorally less affected by castration than does the 7-wk-old pig. Local anesthetic prevented pain-induced behavior changes for 2-wk-old, but not for 7-wk-old, pigs. At present, the FDA does not permit use of these anesthetics in meat-producing animals.

Physiology and behavior of pigs before and after castration: effects of two topical anesthetics

“…Local anesthetic administered either using a needle and syringe (McGlone and Hellman, 1988) or topically as in this study appeared to reduce abnormal lying behaviors in piglets as compared with piglets castrated without anesthesia. Nursing behavior was reduced in pigs after castration by 8.6% (McGlone and Hellman, 1988). In this study, there was no difference in nursing behavior among castration treatments.…”

“…Taylor et al (2001) found that piglets spent less time lying after castration compared with control piglets, but they did not differentiate between lying with and without contact. McGlone and Hellman (1988) observed that piglets castrated without anesthesia spent more time lying away from the heat lamp than control piglets. Local anesthetic administered either using a needle and syringe (McGlone and Hellman, 1988) or topically as in this study appeared to reduce abnormal lying behaviors in piglets as compared with piglets castrated without anesthesia.…”

“…McGlone and Hellman (1988) observed that piglets castrated without anesthesia spent more time lying away from the heat lamp than control piglets. Local anesthetic administered either using a needle and syringe (McGlone and Hellman, 1988) or topically as in this study appeared to reduce abnormal lying behaviors in piglets as compared with piglets castrated without anesthesia. Nursing behavior was reduced in pigs after castration by 8.6% (McGlone and Hellman, 1988).…”

“…Until a practical alternative to surgical castration is developed, there is a need to develop practical on-farm pain relief for piglets during castration. Local anesthesia has been used as a method to reduce the physiological and behavioral response to surgical castration in piglets (McGlone and Hellman, 1988;White et al, 1995;Leidig et al, 2009) and other species (Fisher et al, 1996;Dinniss et al, 1997;Molony et al, 1997;Stafford et al, 2002). However, it is impractical to use an injectable local anesthetic as a pain relief on the farm due to the increased time and stress caused by the need to repeatedly handle animals, once to administer the local anesthetic and the second time to castrate the animal.…”

“…A local anesthetic given before castration has been shown to reduce and even eliminate the cortisol response to castration in several species, including lambs (Dinniss et al, 1997;Molony et al, 1997) and calves (Fisher et al, 1996;Stafford et al, 2002). Local anesthetic was also shown to prevent the reduction in nursing and lying (without contact) behaviors in piglets in response to castration (McGlone and Hellman, 1988), and piglets given a local anesthetic before castration vocalized less during castration than those not given an anesthetic (White et al, 1995;Leidig et al, 2009). However, the disadvantages to using a local anesthetic include the time and stress caused by needing to repeatedly handle piglets; once to administer the local anesthetic and the second time to castrate the animal.…”