Preventing New Lice Infestations in Sheep

Nearly all new infestations begin from contact with infested sheep. Major sources of lice are:

• infested sheep that stray onto a property
• sheep that stray from the property, come into contact with lousy sheep, and later return to the mob
• purchased sheep and sheep brought in from other properties (including sheep returning from agistment)

However, infestations can also result from sheep missed at muster and therefore left untreated in the previous year or from sheep not effectively treated after their previous shearing. Split shearings and treating ewes with lambs at foot or pregnant ewes due to lamb within 6 weeks of treatment are other causes of continuing infestations.

A well-designed lice biosecurity plan that prevents contact with infested sheep is critical to keeping a property lice-free.

Stock-proof fences are essential for good biosecurity. Without them, straying sheep can bring lice onto the property and isolation/quarantine of introduced sheep becomes impossible.

The LiceBoss page Sheep lice—biosecurity can prevent introduction provides guidelines for developing an effective lice biosecurity program.