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Introducing sheep: the lice treatment dilemma

by Deb Maxwell, Operations Manager, ParaBoss

June 2015

Have you considered introducing sheep, but are worried about bringing in lice? Achieving a lice-free flock takes a concerted effort, so the decision to bring in new sheep should not be taken lightly. But the many options and considerations, as well as the difficulty in detecting whether lice are indeed present, make the decision on how to manage or treat those sheep quite complex.

The LiceBoss Treatment Guide makes a hard decision easy. This new and simple-to-use tool guides you through straightforward questions about your situation. It’s as close as you can get to talking to an expert.  The final report shows your questions and answers plus a set of LiceBoss recommended actions, as well as links to the associated supporting information to help you with whichever decision you ultimately choose.

The dilemma most buyers face is whether the sheep in question actually do have lice because lice are very hard, if not impossible, to find in the following situations.

  • If the sheep have recently been shorn, shearing is enough to get rid of most—but not all—lice; those that remain are hard to find.
  • If the sheep have been treated recently with a chemical to which the resident lice are largely resistant this will kill many, but again, not all lice, with the few remaining generally avoiding detection for some time.
  • If the mob’s recent treatment was applied poorly, with some sheep missing treatment or not being treated correctly, many sheep will be lice free, but those with lice might easily be missed during a mob inspection.
  • If a lousy stray has come on to your property, lice may not be evident in your flock for many months.

It may take six months or more for infestations such as these to become detectable on a thorough inspection. That means, five partings on each side of at least ten sheep looking for lice in good light. In the meantime, these sheep can transfer lice to any sheep they are mixed with.

LiceBoss has seven recommendations for managing introduced sheep, but there are a number of factors to consider first, especially when lice may be present, but have not been positively identified.

A key factor is the number of sheep purchased compared to the home flock size. Many an unsuspecting ram buyer has brought lice in when buying a small number of rams. In this situation, the most rigorous biosecurity approach is to shear and treat the rams as soon as they arrive home, and keep them isolated after treatment as per the product label. Consideration needs to be given to ensure at least seven weeks between shearing and joining to avoid any possible effects on ram fertility.

However, the ‘shear and treat’ option can be expensive for larger mobs, primarily because one and sometimes a later second premature shearing (to line up shearing times) can greatly reduce the wool value. The LiceBoss Treatment Guide therefore also considers your ability to isolate or quarantine the mob, the amount of wool growth currently on the sheep, and the impact introduction of lice to your flock would have on your business.

The LiceBoss Treatment Guide provides a robust recommendation on what actions you should take to introduce sheep so as to maintain your lice-free status. However, it also allows you to see the other less robust recommendations, so that ultimately, you can make your choice on the practices and level of risk you are prepared to undertake.

Each recommendation will also link you to the relevant information and tools on the LiceBoss web site to assist your choice of application method and product. As application is a key factor in successful treatment, you are also directed to the instructions on how to best set up and use application equipment.

Next time you are considering introducing sheep, or have found a stray in your flock, immediately think of the LiceBoss Treatment Guide. The Guide is easy to find at by choosing ‘Solve your current lice issue’ or Tools, in the main menu.