Mulesing - surgical removal of wool-bearing skin folds to prevent flystrike - is a painful and controversial practice with humane alternatives increasingly available.
Mulesing causes significant acute suffering in young lambs. The procedure is typically performed without adequate analgesia historically, though this is improving. The resulting wound is painful for days and vulnerable to secondary infection. However, untreated flystrike causes even more extreme suffering, with maggots consuming living tissue causing severe pain, toxemia, and death. The welfare debate is about which harm is greater - the acute pain of mulesing or the potential catastrophic suffering of flystrike. The real welfare solution is selective breeding for plain breech conformations that eliminate the need for either mulesing or intensive blowfly management.