Surgical castration is a common management practice performed on male pigs to prevent the occurrence of boar taint. Surgical castration is known to cause physiological and behavioral changes in pigs indicative of pain-induced distress; however, it is commonly performed without pain relief. The objective of this study was to evaluate the effectiveness of carbon dioxide gas (CO(2)) anesthesia and a non-steroidal anti-inflammatory drug (NSAID) to alleviate the pain caused by castration. At 3 d of age, male pigs were either control handled (CON), castrated without pain relief (CAS), given an NSAID and then immediately castrated (CAS+NSAID), anesthetized with CO(2) and then castrated (CAS+CO2), or anesthetized with CO(2) and given an NSAID at the time of castration (CAS+BOTH). Blood samples were collected before castration, and at 30, 60, 120, and 180 min, 24 h, and 3 d after castration or handling for analysis of cortisol, C-Reactive protein (CRP), and substance-P (SP) concentrations. This study was then repeated using the same treatment groups, and the behavioral response to castration and handling were measured using a 1-min scan sampling procedure. The percentage of stress vocalizations was recorded during the administration of all treatments. Anesthesia and analgesia did not effectively reduce (P > 0.05) the cortisol response to surgical castration. Overall, CRP concentrations were greater (P < 0.05) in CAS+CO2 pigs as compared with CON pigs. Sixty minutes after castration or handling, SP concentrations were greater (P < 0.08) in pigs given CO(2) anesthesia (CO2, CAS+CO2, and CAS+BOTH) than CON, CAS, and CAS+NSAID pigs. Pigs castrated without pain relief spent more (P < 0.001) time lying without contact than all other treatments during the first 30 min after castration, but thereafter CAS+CO2 pigs spent more (P < 0.001) time lying without contact than other treatments. During the first 30 min after the treatments were applied, CAS+CO2 pigs spent more (P < 0.01) time displaying pain-like behaviors than CON, CAS, CAS+NSAID, and CAS+BOTH pigs. The percentage of stress vocalizations was greater (P < 0.05) in CAS and CAS+NSAID pigs than all other treatments. Neither CO(2) anesthesia nor a NSAID, given separately or combined, markedly reduced the pain-induced distress caused by castration in pigs. More research is needed to evaluate practical methods of on-farm pain relief for pigs.

Surgical castration of male piglets is a common management practice conducted on commercial swine farms to prevent the occurrence of boar taint and aggressive behavior. However, the procedure of surgical castration causes acute pain-induced distress, which is an animal welfare concern. The objective of this study was to evaluate the use of two topical anesthetics to alleviate the pain caused by castration in piglets as measured by physiological and behavior indices of stress. At 3 days of age, 40 weight-matched piglets were allocated to one of four treatment groups. Treatments included: (i) sham castration (CON), (ii) surgical castration (CAS), (iii) castration and short-acting local anesthetic applied topically to the castration wound (SHORT) and (iv) castration and long-acting local anesthetic applied topically to the castration wound (LONG). Blood samples were collected from piglets before and 30, 60, 120 and 180 min after castration to measure leukocyte and differential counts and cortisol concentrations. The above experiment was repeated without blood collection and behavior was recorded for 30 min before and 180 min after castration or handling. Stress vocalizations were recorded during castration and handling. All piglets were weighed before and 24 h after castration and wound healing was recorded daily for the first 14 days after castration. Leukocyte counts and differentials did not differ ( P . 0.05) among any of the treatments. Cortisol concentrations were elevated ( P , 0.06) in CAS, SHORT and LONG piglets compared with controls 30 and 60 min after castration. The percentage of stress vocalizations was greater ( P , 0.05) among castrated piglets compared with CON piglets, regardless of anesthetic treatment. Piglets that were castrated and not given a topical anesthetic spent more time ( P , 0.05) lying without contact compared with piglets castrated and given a topical anesthetic, regardless of the topical anesthetic administered. Body weight change did not differ ( P . 0.05) among treatments 24 h after castration or control handling and wound healing scores were greater ( P , 0.05) in SHORT compared with CAS and LONG piglets 9 to 14 days after castration. In this study, the use of a short-or long-acting topical anesthetic was not effective in reducing the pain-induced distress caused by castration in piglets. Further research is needed to evaluate alternative practical methods to reduce the pain caused by the on-farm castration of piglets.

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The objectives of this study were to determine i) the effect of castration, dehorning, or both on the physiology and behavior of 3-mo-old Holstein calves, and ii) the effectiveness of pain relief to alleviate the pain caused by castration and/or dehorning. Holstein calves (n = 80) were assigned randomly to 1 of 8 treatments (10 calves/treatment): i) control handling (SHAM); ii) surgical castration (CAS); iii) dehorning (DH); iv) surgical castration and dehorning (CD); v) control handling plus pain relief (ANA); vi) surgical castration plus pain relief (CAS+A); vii) dehorning plus pain relief (DH+A); or viii) surgical castration and dehorning plus pain relief (CD+A). Pain relief consisted of administering local anesthetic and a nonsteroidal anti-inflammatory drug (NSAID) immediately before castration, dehorning, or both. Sequential blood samples were collected to measure leukocyte counts and cortisol concentrations. Behavior was recorded using 5-min scan samples during the first 3 h after application of the treatments. Calves were weighed before and 24 h after treatment application. Calves dehorned spent more time head shaking (p < 0.001) and ear flicking (p < 0.05), and CD calves spent more time ear flicking (p < 0.05) and foot stamping (p < 0.01) than SHAM handled calves. Calves castrated, dehorned, or both spent less (p < 0.01) time eating compared with sham handled calves. Giving calves pain relief before castration and/or dehorning increased (p < 0.05) the time spent eating compared with CAS, DH, and CD calves. At 6 h posttreatment, neutrophil to lymphocyte ratio was greater (p < 0.01) in castrated and/or dehorned calves compared with SHAM-handled calves. Castration and/or dehorning also increased (p < 0.05) cortisol concentrations for at least 4 h after these procedures were performed; however, administering pain relief before castration and/or dehorning markedly reduced (p < 0.05) this response. Behavioral and physiological changes caused by castration, dehorning, or both are indicative of calves experiencing pain for at least 4 h after application of these procedures, and these responses were additive when performed together. Therefore, providing calves with pain relief, in the form of local anesthetic and an NSAID, can markedly reduce both the behavioral and physiological response to these procedures.

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