Impact of topical anaesthesia on pain alleviation and wound healing in lambs after mulesing

OBJECTIVE: To investigate the impact of using the topical anaesthetic preparation Tri-Solfen on pain alleviation and wound healing in lambs undergoing mulesing. DESIGN: Three separate trials, placebo controlled and/or randomised, were carried out over a 5 month period on three mobs of between 60 and 263 merino lambs undergoing routine mulesing. PROCEDURE: Wound pain was assessed using 10 and 75 g calibrated Von-Frey monofilaments to determine sensitivity to light touch and pain stimulation over a 4 to 8 h period. Pain-related behaviour was documented by trained, blinded observers using a numerical rating scale. Wound healing rates were determined using scaled digital photography and image analysis software to calculate contraction in wound surface area 2 and 4 weeks after mulesing. RESULTS: There was rapid (3 min) and prolonged (up to 8 h) wound analgesia as shown by pain response scores (P < or = 0.01), with absent or significantly diminished primary and secondary hyperalgesia (P < or = 0.01) and significant reduction in pain-related behaviour (P < 0.001) in treated versus untreated lambs. In addition there was improved wound healing in the treated lambs (P < or = 0.05). CONCLUSION: Tri-Solfen effects rapid and prolonged wound analgesia, reduction in pain-related behaviour and improved wound healing in lambs undergoing routine mulesing, providing effective alleviation of pain associated with routine mulesing in sheep.