The analgesic effect of preventive administration of meloxicam in calves submitted to hot-iron dehorning

Abstract

Dehorning is a zootechnical practice that causes severe pain in cattle. Although there are several studies evaluating the effects of analgesics in calf dehorning, none of them used validated pain assessment instruments. We evaluated the analgesic effectiveness of meloxicam administered before dehorning, compared to a control group, using the Unesp-Botucatu, numerical, simple descriptive, and visual analogue scales for pain assessment before and 4, 8, and 24 hours after the dehorning in 44 female calves. All calves received 0.04 mg/kg of xylazine IM 20 minutes before dehorning and local anesthetic block with 2% lidocaine with a vasoconstrictor. Calves were divided into two groups: without (GX; n = 22) or with 0.5 mg/kg of meloxicam (GXM; n = 22) administered intravenously before the procedure. Dehorning was performed through the section of the base of the horn bud, followed by thermocautery disbudding. For comparisons over time, mixed linear or generalized mixed linear model were used. The interaction between groups and study phases was used as fixed effects and each calf as a random effect. Bonferroni post hoc test was used. There was an increase in the pain scores at 4h compared to baseline in both groups (GX and GXM) for the four scales. The scores at 4h were higher in GX compared to GXM for all scales. Meloxicam reduced, but did not eliminate, behavioral expressions of pain in calves submitted to hot-iron dehorning. Therefore, it should be included in the analgesic protocol to improve welfare in calves undergoing dehorning.