Word of the Day - Mulesing

Mulesing is the surgical removal of strips of wool-bearing wrinkle skin from around the tail (basically the asshole) of a sheep. Mulesing is common practice in Australia, where it is expected to be phased out by 2010. It is performed as a way to prevent *flystrike on farms where risk of flystrike is considered high. Current veterinary opinion considers the practice to be a necessary compromise in providing for the general welfare of sheep in areas of Australia.

History

Mulesing is named after Mr J.W.H. Mules. Mules discovered that, after being struck many times, one of his sheep was losing the wrinkles round her hind end due to close crutching when his hand slipped with the shears, removing skin. After performing this procedure on his other sheep, Mules noticed that it prevented the occurrence of flystrike. The procedure was refined and experimented with and demonstrated to reduce flystrike. It was approved for use in Australia in the 1930s. This practice therefore greatly assists in the prevention of flystrike in the Australian environment. In Australia, it is thought that the fly primarily responsible for flystrike, Lucilia cuprina, was introduced from South Africa in the nineteenth centry.

Originally, mulesing was carried out on sheep after they were weaned because it was considered 'too rough' for lambs. However, lambs appear to cope with the procedure better than older sheep as the actual area of skin fold removed on young lambs is quite small, and they are protected for an extra year as well. The discomfort period for young lambs (>2 months) seems to be for approximately two weeks by which time healing is almost complete. Current codes of practice ban mulesing for sheep over 12 months of age.

Method

While the lamb is under restraint (typically in a marking cradle), the wrinkled skin in the animal's breech (rump area) is cut away from the perianal region down to the top of the hindlimbs. Originally, the procedure was typically performed with modified wool-trimming shears, however there are now similar shears designed specifically for mulesing. In addition, a portion of the tail is removed and the remaining stump is skinned. The cuts are executed to avoid affecting underlying muscle tissue.

The New South Wales Department of Primary Industries states in the Standard Operating Procedures that, "While the operation causes some pain, no pre or post operative pain relief measures are used". Antiseptics are often applied, but anaesthesia and painkillers are not required during or after the procedure. Products have been approved for pain relief during the procedure, including Tri-Solfen - however the use of pain relief is not currently required by Australian industry practices. The registration makes the product available for use by both veterinarians, and sheep industry employees such as mulesing contractors and graziers.

The non-wooled skin which is around the anus (and vulva in ewes) is pulled tight as the cut heals and results in a smooth area that does not get fouled by excreta or urine.

Lambs are normally mulesed a few weeks after birth. The operation takes one to two minutes. Standard practice is to do this operation simultaneously with other procedures such as ear marking, tail docking, and vaccination. Because it is a skin snip, there is little blood loss from the cut other than a minor oozing on the edges of the cut skin. Lambs rarely die or become ill after mulesing.

Mulesed lambs should be released onto clean pasture. The ewes and suckling lambs should receive minimal disturbance until all wounds are completely healed (about 4 weeks). Observation should be carried out from a distance.

Mulesing should be completed well before the flystrike season or else chemical protection should be provided to reduce risk to the lambs and ewes.

Lambs that are slaughtered soon after weaning generally do not need mulesing as they can be protected by chemical treatment for the short time they are at risk.

*Myiasis is an animal or human disease caused by parasitic dipterous fly larvae feeding on the host's necrotic or living tissue. Colloquialisms for Myiasis include "fly-strike" and "fly-blown".