Effect of Lidocaine and Meloxicam on Indicators of Pain and Distress after Knife Castration in Weaned Beef Calves

Castration is commonly done without the use of pain mitigation, although previous studies have shown that the combination of an analgesic and an anesthetic drug is more effective at mitigating pain than either drug on its own. The aim of this study was to assess the efficacy of the combination of a lidocaine (2% with epinephrine) ring block 30 min prior to knife castration in combination with a single dose of s.c. meloxicam (Metacam 0.5 mg/kg BW) administered immediately prior to castration. Forty-eight Angus bull calves (301.4 ± 5.8 kg BW) were randomly assigned to a 2 × 2 factorial design assessing administration of meloxicam and lidocaine: no-meloxicam and lactated ringer ring block (NM-NL; n=12), no-meloxicam and lidocaine ring block (NM-L; n=12), meloxicam and lactated ringer ring block (M-NL; n=12), and meloxicam injection and lidocaine ring block (M-L; n=12). Data was collected on d −1, immediately before castration, 30, 60, 120, 240 min and on d 1, 2, 3, 6, 14, 21, and 28 after castration. Physiological parameters consisted of salivary cortisol (SC), haptoglobin (HP) and scrotal temperature (ST). Behavioral parameters included stride length (SL) and visual analog score (VAS). A Lidocaine × Time effect (P < 0.01) was observed for SC, L calves had lower concentrations compared to NL calves 30 and 60 min after castration. In addition, M calves had lower SC concentrations (P = 0.03) compared to NM calves during the first 240 min after castration. A Meloxicam × Time effect (P = 0.05) was observed for HP with M calves having lower concentrations compared to NM calves on d 1, 2 and 3 after castration. The L calves had lower VAS scores (P = 0.01) compared to NL calves. No treatment differences were seen in SL (P > 0.3) or ST (P > 0.05). Despite the fact that there was no interaction between lidocaine and meloxicam, lidocaine was more effective at mitigating the indicators of pain at the time of and up to 1 hour after castration, while meloxicam was more effective at reducing indicators of pain 3 hours and 3 days after castration. In this study the combination of lidocaine and meloxicam was more effective in controlling pain during and up to 3 days after castration than each drug alone.