Efficacy of precisely injected single local bolus of lignocaine for alleviation of behavioural responses to pain during tail docking and castration of lambs with rubber rings

Abstract

Delivery of local anaesthetic at the time of castration and tail docking (marking) could improve welfare outcomes in lambs. This study examined pain responses in lambs marked using rubber rings, with or without local anaesthetic precision injected using the Numnuts® instrument. On each of two commercial farms, 150 prime lambs aged 4 to 10 weeks, balanced for sex, were randomly allocated to 3 treatments: handled in a lambing cradle (Sham), handled and marked with rubber rings (Ring) or handled and marked with rubber rings and treated with 30 mg lignocaine using the Numnuts® instrument (NNLA). Time to mother up (one trial site only), acute pain related behaviours at 5, 20, 35 and 50 min, and postures at 10 min intervals from 60 to 180 min were recorded. NNLA lambs tended to mother up more quickly than Ring lambs (P = 0.09), and more slowly (P = 0.07) than Sham lambs. Acute pain behaviours were significantly more frequent in Ring and NNLA than Sham (P < 0.001) from 5 to 50 min. NNLA was significantly lower than Ring at 5 min (P < 0.001) and 20 min (P = 0.001). Ring and NNLA did not differ at 35 or 50 min. Abnormal postures were higher in Ring and NNLA than Sham at 60, 70, 80, 90 and 150 min (P < 0.048). Ring and NNLA did not differ at any time point between 60 and 180 min. Delivery of lignocaine with the Numnuts® instrument improved welfare outcome of lambs during the acute pain response caused by castration and tail docking with rubber rings.

Keywords: Analgesia; Behaviour; Ischemia; Local anaesthetic; Numnuts; Sheep.