The impact of meloxicam on postsurgical stress associated with cautery 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, 20mg/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 (0.5mg/kg). All calves were given a lidocaine cornual nerve block delivered 5mL per side 10min before dehorning. To establish baseline values, calves were sham dehorned 24h before actual dehorning. Blood samples were taken via indwelling jugular catheters at 0, 0.5, 1, 1.5, 2, 4, 6, and 24h 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 24h, and elevated respiratory rate (sham: 42.2±1.95 vs. dehorning: 45.1±2.19 respirations per minute) in both groups for 6h. A treatment × time interaction was found for cortisol, with meloxicam calves having lower serum cortisol than controls until 6h after dehorning (meloxicam: 49.7±4.37 vs. control: 63.0±6.94 nmol/L). There was no difference between the treatment groups at 24h (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.