Evaluation of the Effect of Extended-Term Delivery of Local Anesthetic on Mitigating the Pain Caused By Castration

Abstract The objective of this study was to evaluate the effects of the extended-term delivery of anesthesia on the physiological and behavioral signs of pain caused by band castration in 1-month-old bull calves. Forty-eight calves (37.04 ± 8.98 days of age) were homogenously assigned by age to one of three band castration protocols (n = 16/protocol); 1) regular elastrator bands (REG), 2) regular elastrator bands preceded by two 2-mL injections of lidocaine (REG+L; LIDO-2 with epinephrine, Rafter 8 Products Inc, Calgary, Canada), and 3) lidocaine elastrator bands (LBAND; Care-Ring, Chinook Contract Research Inc., Calgary, Canada). During the castration procedure, two observers scored (from 1 to 10) how much pain each animal was experiencing (visual analog score, VAS), number of body shakes and leg kicks for each calf. Calves were weighed on d -1, 0, 14, 28, 42, and 56. Hair cortisol concentration was measured on d -1, 28, and 56. Saliva cortisol concentration was measured right after castration, 60, 120, 240 minutes after castration, on d 1 and weekly thereafter until d 56. Flight speed (FS) was recorded on d -1, right after castration, 60, 120, 240 minutes after castration, d 1, and weekly thereafter until d 56. Calf behaviors in the pen indicative of pain and discomfort were recorded on d 0, 1, and weekly thereafter until d 56. The REG+L calves tended to have decreased (P = 0.09) VAS scores than REG calves. The average daily gain was greater (P < 0.01) from d 42 to 56 than from d 1 to 42, and from d 1 to 28 compared with d 28 to 42 in all treatment groups. The REG calves had decreased (P < 0.01) hair cortisol concentrations than both REG+L and LBAND calves. Saliva cortisol concentrations were greater (P < 0.01) 60 minutes after castration than any other sample time in all treatment groups. There was an interaction between treatment and time (P = 0.04), where only LBAND had a greater FS immediately after castration compared with d -1. When calves were observed in the pen there were no treatment effects (P > 0.10) but only time differences (P < 0.05) in the frequency of head turns, oral behaviors, tail flicks, and number of standing and walking bouts. The behavioral and physiological parameters assessed showed expected results on the effects of band castrating calves, while the administration of lidocaine via REG+L or LBAND did not show any pain mitigation effect compared with the standard industry banding method (REG).