RESUMO
The purpose of this study was to investigate the effects of perioperative administration of oral meloxicam prior to and following the application of caustic paste to disbud neonatal dairy calves. Sixty-one 3-4-d-old Holstein heifer calves were randomly assigned to one of four treatment groups of 15-16 calves. The treatment groups were: 1) M1, caustic paste disbudding and oral meloxicam (45 mg) with a placebo 24 h later; 2) M2, treatment M1 followed by a second 45-mg dose of meloxicam 24 h later instead of placebo; 3) CONTROL, treatment M1 with placebo in place of meloxicam; and 4) SHAM, sham disbudding with placebo in place of meloxicam. Infrared thermography was used to quantify eye and horn bud temperatures. Pressure algometry was used to measure Mechanical nociceptive threshold (MNT) surrounding the horn bud. Average daily gain and body weight (BW) were obtained by weighing each animal throughout the study and calculating the changes over time. Plasma was collected and analyzed for cortisol and substance P concentrations. Substance P and cortisol decreased in all animals over time, regardless of treatment. Mean plasma substance P concentration across all time points was greater (P < 0.05) in the SHAM group than M1 or M2 but not different (P > 0.05) than the CONTROL group. The MNT and ocular temperatures decreased over time across all treatments (P < 0.05). Mean BW increased over time across all treatments (P < 0.05). A significant interaction (P < 0.05) between treatment and sampling time was observed at 12 h following treatment application for both mean horn bud temperature and the ratio between horn bud and ocular temperature. Overall, the results of this study suggest that meloxicam administration at a dose of 45 mg per animal may have limited influence as the primary modulator of pain and inflammatory response in calves that have been disbudded with caustic paste at 3 d of age.
