An investigation of meloxicam for the relief of pain associated with dehorning of dairy calves

The objectives of this study were to investigate the duration of pain following dehorning by heat cauterization with a lidocaine local block and to assess the efficacy of meloxicam, a non-steroidal anti-inflammatory drug, for relieving that pain. Sixty Holstein heifer calves ranging in age from 6-12 weeks were tested in groups of two or four calves for a total of 17 trials. Calves were blocked by age and randomly assigned to meloxicam or placebo treatments at a dosage rate of 0.5mg/kg. A sham dehorning treatment was performed 24 hours before dehorning to establish baseline values for all pain-related variables. Three categories of pain assessment tools were used: physiological (serum cortisol, heart rate and respiratory rate), mechanical (pain sensitivity involving a withdrawal response to pressure algometry) and behavioural (behaviours quantified from digital videorecording, general activity and feed intake). Both treatment groups showed increases cortisol, heart rate, respiratory rate, pain sensitivity and pain-related behaviours in response to dehorning. When statistically significant, these responses were always lower in meloxicam treated calves. Meloxicam calves were less active for the first five hours following dehorning and ate more the day following dehorning than placebo calves. The pain response to dehorning appears to last at least 44 hours. Meloxicam appears to be effective at relieving the pain response as measured by physiological, withdrawal and behavioural responses.