Effects of a single injection of meloxicam on calf behavior, pain sensitivity, and feed and water intakes were examined following dehorning. Sixty Holstein heifer calves were blocked by age and randomly assigned to receive an i.m. injection of meloxicam (0.5 mg/kg) or a placebo. All calves were given a lidocaine cornual nerve block (5 mL per horn). Treatments and nerve blocks were administered 10 min before cautery dehorning. Continuous sampling of behavior was performed during five 1-h intervals using video recordings, and total daily activity was monitored using an accelerometer. A pain sensitivity test was administered with a pressure algometer, and feed and water intakes were recorded daily. Calves were sham-dehorned 24 h before actual dehorning to establish baseline values, and all variables were assessed at the same times following dehorning and sham dehorning for up to 48 h post-dehorning. Meloxicam-treated calves displayed less ear flicking during the 44 h following dehorning (increases of 4.29+/-1.10 and 1.31+/-0.66 ear flicks/h in the first 24 h, and increases of 3.27+/-0.89 and 0.55+/-0.50 ear flicks/h during the second 24 h, for control and meloxicam calves, respectively) and less head shaking during the first 9 h following dehorning (increase of 2.53+/-0.54 and 0.85+/-0.46 headshakes/h over baseline for control and meloxicam, respectively). Meloxicam-treated calves were less active than controls during the first 5 h following dehorning (activity 34.1+/-3.2 and 30.6+/-2.6 for control and meloxicam, respectively) and displayed less sensitivity to pressure algometry 4 h after dehorning (pressure tolerance of 1.62+/-0.13 kg of force and 2.13+/-0.15 kg of force for control and meloxicam calves, respectively). Changes in behavior suggest that meloxicam was effective for reducing post-surgical pain and distress associated with calf dehorning.

The objectives were to determine the duration of the stress response associated with cautery dehorning and to assess the effectiveness of the nonsteroidal anti-inflammatory drug meloxicam (Metacam, 20 mg/mL solution for injection) for reducing that response. Sixty Holstein heifer calves were blocked by age and randomly assigned to receive an i.m. injection of meloxicam or a placebo (0.5 mg/kg). All calves were given a lidocaine cornual nerve block delivered 5 mL per side 10 min before dehorning. To establish baseline values, calves were sham dehorned 24 h before actual dehorning. Blood samples were taken via indwelling jugular catheters at 0, 0.5, 1, 1.5, 2, 4, 6, and 24 h after the procedure. Heart and respiratory rates were also taken at these times. Data were analyzed using PROC MIXED in SAS. Analysis of covariance was employed to assess the difference between sham and dehorning at each time period. Dehorning was associated with elevated serum cortisol (d -1: 33.9 +/- 1.26; d 0: 46.2 +/- 2.33 nmol/L) and heart rate (d -1: 108 +/- 1.8; d 0: 109.4 +/- 2.4 beats per minute) in both groups for 24 h, and elevated respiratory rate (sham: 42.2 +/- 1.95 vs. dehorning: 45.1 +/- 2.19 respirations per minute) in both groups for 6 h. A treatment x time interaction was found for cortisol, with meloxicam calves having lower serum cortisol than controls until 6 h after dehorning (meloxicam: 49.7 +/- 4.37 vs. control: 63.0 +/- 6.94 nmol/L). There was no difference between the treatment groups at 24 h (meloxicam: 35.2 +/- 2.74 and control: 34.8 +/- 3.64 nmol/L of cortisol). Overall, the changes in heart rates (increase meloxicam: 3.74 +/- 0.96 vs. control: 4.70 +/- 1.87) and respiratory rates (increase meloxicam: 2 +/- 0.1 vs. control: 4 +/- 0.2) were greater in the control group compared with the meloxicam group. These results indicate that meloxicam reduced the physiological stress response to dehorning.