Abstract
Forty Hereford cross calves (mean and SD of 47.9 ± 10.43 d old) were used to assess the efficacy of lidocaine administered immediately before surgical castration on physiological and behavioral indicators of pain and discomfort. Calves were assigned by age to one of two treatments: surgical castration following subcutaneous injection of 2.5 mL/100 kg body weight of meloxicam (Metacam 20 mg/mL, Boehringer Ingelhein, Burlington, ON, Canada) per kg body weight (MEX, n = 19); or the same treatment preceded 90 s before by a nerve block of the spermatic cord using 8 mL of buffered (1 mL:10 mL of 8.4% sodium bicarbonate USP, Hospira Inc., Lake Forest, IL, USA) lidocaine (4 mL per cord; 20 mg/mL, LIDO-2 with epinephrine, Rafter Products, Calgary, AB, Canada) (LID, n = 21). During the castration procedure, two observers scored how much pain each animal was experiencing (visual analog score, VAS), number of body shakes and leg kicks for each calf. Blood samples and exit scores were collected the day of castration and on d 7, and 14 to assess the neutrophil-to-lymphocyte ratio (N:L) and calf temperament, respectively. Hair samples were collected the day of castration and on d 14 to determine cortisol levels. Scrotal circumference, swelling, and healing scores were determined on d 7 and 14 to assess healing. An accelerometer (HOBO Pendant® G Data Logger, Onset, Cape Cod, MA) was placed on the left hind leg to measure lying behavior until d 6 after castration. Calves were video recorded for 1 hour after the castration procedure to observe behaviors indicative of pain and discomfort. Surveillance cameras were also used to assess the mobility of the calves when cow-calf pairs were moved from the holding pen to the pasture. The VAS, number of tail flicks and foot stamps were greater (P < 0.01) in MEX than in LID calves. During the first hour after castration, LID calves spent more time lying (P = 0.03) and less time standing (P = 0.01) than MEX calves. When moved from the holding pen, LID calves moved faster (P < 0.01) and closer to their dams (P < 0.05) than MEX calves. Hair cortisol was greater (P < 0.05) in LID than MEX calves on d 14. Results suggest that using lidocaine for local anesthesia immediately before surgical castration reduced behaviors indicative of pain and improved mobility post-castration.