Use of local anaesthesia for pain management during husbandry procedures in Australian sheep flocks

Abstract

Mulesing (removal of breech skin for blowfly strike control), castration, tail-docking and ear-knotching are routine husbandry procedures conducted on many millions of lambs annually in Australia, causing considerable pain and suffering. However, establishing an effective alternative to mulesing is proving to be a difficult and prolonged process. This is particularly so for producers of high-quality fine wool from Merino sheep that have been selected over many generations for skin wrinkle to increase yields, increasing their susceptibility to flystrike by Lucilia cuprina. In late 2005, a spray-on product formulation containing two topical analgesia agents (lignocaine and bupivacaine) for pain relief at mulesing has become commercially available. Increasingly, fine-wool growers have been choosing to continue surgical mulesing, but adopting pain alleviation at surgical mulesing to reduce suffering. This product has led to the development of the “Better Choices” program, in an effort to meet international concerns that mulesing without pain relief was cruel. Studies have been conducted on the use of these products for decrease of pain induced by surgical mulesing, castration and tail-docking. A technique has been developed to measure pain through assessment of wound sensitivity using Von-Frey Hair stimulation, measuring local involuntary reflexes and central cognition. These responses were graded using a numerical rating scale. Behavioural responses to pain were analysed by video. A novel technique was developed to assess the rate of wound healing by digital photography and computerized surface area measurement. Also, a method of application was developed at castration, which enabled analgesia of the remaining scrotal contents, with impressive results compared to other methods of castration such as the use of rubber rings. Findings from a series of field and pen trials indicate that the immediate application of spray-on topical anaesthesia to mulesing, castration and tail-docking wounds, significantly reduced the pain experienced post-procedure and improved the rate of wound healing. Increasing adoption by producers of pain relief for lambs during surgical routine husbandry procedures offers a new welfare-conscious paradigm for the Australian wool industry. This development has potential application to several species undergoing many livestock procedures throughout the world and offers a simple part solution to address the increasingly important and emerging global issue of welfare conscious agriculture.