Pain management with flunixin meglumine at dehorning of calves.

Dehorning (DH) of calves is a common procedure on commercial dairy farms. Pain management of calves has been investigated in several studies. It is generally accepted that the use of local anesthesia before DH is essential for pain management. Postoperative inflammatory pain should be treated by using a nonsteroidal antiinflammatory drug. The objective of this controlled, randomized, and blinded clinical trial was to determine the effects of the nonsteroidal antiinflammatory drug flunixin meglumine before DH on cortisol concentrations in sera of 5- to 9-wk old calves. Furthermore, selected behavioral characteristics and heart and respiratory rate were examined to assess pain in the hours after dehorning. A total of 80 calves were allocated to 4 groups. In each of 20 replicates, 4 calves were randomly assigned to the following groups: in 3 treatment groups, calves received a local anesthetic (10 mL of procain hydrochloride) and a first treatment (i.v.) with flunixin meglumine or a placebo 20 min before hot-iron dehorning, and a second treatment with flunixin meglumine or a placebo (0.9% saline) 3 h after DH. Calves in the control (CON) group were not dehorned and did not receive any treatment. Groups received 2.2 mg of flunixin meglumine/kg followed by a placebo (FP), 2.2 mg of flunixin meglumine/kg for both treatments (FF), or a placebo for both treatments (PP). Blood samples were collected from all calves, including CON calves, 20 min before restraint in a headlock for DH, 2 min after DH, as well as 30 min and 1, 2, 4, 6, and 8 h after DH. Samples were analyzed for concentration of cortisol by enzyme immunoassay. It was found that concentration of cortisol, calculated as area under the curve, was greater in PP compared with FF and tended to be greater compared with FP. Significant differences between PP and FF were detected at 30 min and 2 h after DH. Throughout the observation period, cortisol concentrations were in both flunixin meglumine-treated groups at a similar level as in the CON group. The heart and respiratory rates showed neither difference between the CON group and the 3 dehorned groups nor between the treatment groups.