Effect of local infusion of NSAID analgesics administered alone or in combination on the pain associated with band castration in calves.

OBJECTIVE To evaluate the analgesic efficacy of flunixin alone or in combination with diclofenac administered locally to the scrotum at the time of band castration of calves. METHODS Angus bull calves (n = 40; ≈7-9 weeks old) were allocated to four treatment groups (n = 10 per group) to examine the effects of two non-steroidal anti-inflammatory analgesics (NSAIDs) administered locally at the time of band castration: sham control; castration + flunixin; castration + flunixin + diclofenac; castration + saline. The NSAIDs and saline were administered subcutaneously into the scrotum under the band. Blood was sampled at -0.5, 0.5, 1.5, 3, 12, 24, 48 and 72 h relative to castration. Haematology parameters and plasma cortisol levels were determined in samples at all time points and plasma haptoglobin levels determined in samples collected at -0.5, 24, 48 and 72 h. Pain avoidance and postural behaviours were measured for 2 and 12 h, respectively, after castration. RESULTS Band-castrated calves exhibited significantly higher peak cortisol and higher integrated cortisol responses during the first 6 h post-castration relative to sham controls. Individual active pain avoidance behaviours observed for 1 h post-castration were not significantly different between treatment groups; however; the sum of the total behaviours was significantly increased by castration (P = 0.023). Postural changes included increased abnormal ventral lying for all castrated groups and decreased normal standing and increased combined abnormal postures for the flunixin- and saline-treated groups. Growth rates of calves were not affected by treatments during weeks 1 and 2 post-castration; however, growth rates of castrated calves were significantly lower than those of sham-treated calves in week 3 post-castration (1.41 vs 0.84, 0.75 and 0.56±0.19 kg/day for sham, flunixin-, flunixin + diclofenac- and saline-treated groups, respectively). CONCLUSIONS The administration of flunixin or flunixin + diclofenac intrascrotally at several sites at the time of banding did not improve the welfare of young Angus bull calves undergoing this method of castration when assessed by both physiological and behavioural parameters. In this study, band castration at 7-9 weeks of age had less effect compared with results for older calves reported previously. Further research is required to develop effective analgesic treatments that can be administered at the time of castration to large numbers of animals.