Effects of nonsteroidal anti-inflammatory drugs on long-term pain in calves castrated by use of an external clamping technique following epidural anesthesia

To compare efficacy of flunixin meglumine versus carprofen in controlling pain under field conditions following castration by use of an external clamping technique in calves that received epidural anesthesia. 40 male 5- to 6-month-old calves. Calves were allocated to 4 groups: castrated only (control calves; n=8); castrated 5 minutes after epidural injection of 2% lidocaine (epidural-alone treated calves; 8), castrated after epidural anesthesia and s.c. administration of flunixin meglumine (epidural-flunixin treated calves; 12), and castrated after epidural anesthesia and s.c. administration of carprofen (epidural-carprofen-treated calves; 11 [1 calf not included]). Plasma cortisol concentration was measured before and 6, 24, and 48 hours after castration. Time of arrival at the feed trough at 24 and 48 hours was observed. Calves were observed at 24 and 48 hours for 4 pain-related behaviors. At 6 hours, control calves had significantly higher plasma cortisol concentrations, compared with baseline values and those of epidural-flunixin- and epidural-carprofen-treated calves. At 24 hours, epidural-carprofen-treated calves had significantly lower plasma cortisol concentrations, compared with control calves. At 48 hours, epidural-carprofen-treated calves had plasma cortisol concentrations that were similar to baseline values and significantly lower than epidural-flunixin- and epidural-alone-treated calves. At 24 and 48 hours, epidural-carprofen-treated calves were first to arrive at the feed trough and had fewer pain-related behaviors. s.c. administration of carprofen in combination with epidural injection of lidocaine may improve the welfare of calves castrated by use of an external clamping technique for up to 48 hours.