Mulesing
Also searched as: mulesed, non-mulesed, NM wool, ceased mulesing, Mules operation, breech modification
A surgical procedure performed mainly on Australian Merino lambs that removes wrinkled, wool-bearing skin from the breech to reduce the risk of breech flystrike.
In detail
Merino sheep bred for dense fleeces often carry skin wrinkles around the breech, where urine and feces soil the wool. That moist area attracts blowflies, principally the Australian sheep blowfly Lucilia cuprina, whose larvae feed on the living sheep, a condition called flystrike or cutaneous myiasis. Mulesing removes strips of skin so that the healed, bare scar keeps the area cleaner. The procedure causes considerable pain, which has driven pain-relief products and legal mandates, breeding for plainer-bodied sheep, and buyer demand for non-mulesed wool.
The science and numbers
Australian farmer surveys covering 2003 to 2018 reported annual breech strike in about 2 to 5% of sheep nationally; 47% of respondents mulesed in both 2011 and 2018, while pain relief at mulesing of replacement ewe lambs rose from 59% to 87%. Registered options include a spray-on topical anesthetic wound formulation (Tri-Solfen, containing lidocaine, bupivacaine, adrenaline and cetrimide) and the NSAID meloxicam. One trial found the two combined reduced pain-related behavior while either alone had little effect, and another study detected pain from mulesing with behavioral measures but no benefit from analgesia. Non-surgical control relies on breeding for low breech wrinkle, crutching, timed shearing and preventive insecticides such as dicyclanil and cyromazine, whose growing use raises resistance concerns.
A practical example
A knitwear buyer is choosing between two Merino yarn lots with the same micron. The supplier's documentation shows that one lot was declared non-mulesed and the other carries no declaration. A student evaluating the lots should ask what declaration system was used, who verified it, and whether the claim follows the wool through scouring and topmaking into the yarn actually delivered.
What to distinguish
A non-mulesed claim addresses one welfare practice only; it does not describe flystrike rates, shearing, transport or overall farm welfare. Declarations of pain relief or ceased mulesing differ from never-mulesed claims. Some voluntary standards, such as the Responsible Wool Standard, prohibit mulesing on certified farms. Wool from countries where mulesing is not practiced may carry no declaration at all, so absence of a declaration is not evidence either way.
Origins and history
The procedure, also called the Mules operation after its originator, was introduced in Australia in the 1930s and spread quickly through Merino flocks as lifelong protection against breech strike. An animal-rights campaign in 2004 led global brands to boycott Australian wool, and an industry commitment to end mulesing by 2010 was rescinded for lack of alternatives. New Zealand banned the procedure in 2018. Victoria was the first Australian state to make pain relief for mulesing a legal requirement, with current regulations in operation from July 2020, and Tasmania later followed.
Related terms
Sources & further reading
- Veterinary Parasitology Regional Studies and Reports: Australian surveys on incidence and control of blowfly strike in sheep, 2003 to 2019 (Colvin et al., 2022)
- Animals: An update on Australian policy around lamb marking (Johnston et al., 2024)
- Animal: Behavioural measures reflect pain-mitigating effects of meloxicam with Tri-Solfen in mulesed Merino lambs (Inglis et al., 2019)
- Textile Exchange: Quick Guide to the Responsible Wool Standard
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.