Social distancing for sheep

The importance of quarantining when restocking

A lot of sheep have arrived at properties that have historically only been a self-replacing enterprise.

A lot of sheep have arrived at properties that have historically only been a self-replacing enterprise.


You can't turn back the clock after drench resistant worms or lice spread in your flock.


Turning back the clock after drench resistant worms or lice spread through a flock for sheep producers is not an option.

And after many farmers were forced to de-stock due to the drought, a lot of sheep have now been introduced to properties that have historically only been a self-replacing enterprise.

Unfortunately it's often not just sheep that are introduced to enterprises, worms and lice can also make their way inside presenting some significant future costs to producers not to mention devaluing a wool clip.

Executive Officer of ParaBoss, Dr Deb Maxwell, suggests to always assume the sheep carry both worms and lice that are resistant to various chemical groups.

"You need a well-planned stock introduction policy that is just as well implemented," Dr Maxwell said.

"For worms, the costs would be due to drench resistance. Your property will already have some drench resistance worms, but the type and level of resistance could differ in incoming sheep."

She said on entry to the property quarantine drench the sheep with a combination of at least four unrelated drench actives.

Dr Maxwell also suggested including a liver fluke treatment if sheep have come from a high rainfall area or irrigation areas in eastern states.

"Quarantine the sheep for up to three days after treatment using yards or small secure paddocks," she said.

"Use a small secure paddock and hold them for one to three days with food and water to allow any still viable worm eggs to pass fro the gut into this contained place.

"If feed is green, one day, or of feed is dry or low quality, three days."

After quarantine, Dr Maxwell said to release the sheep onto a paddock most heavily contaminated with worm larvae due to grazing by existing sheep as this dilutes any possible worm eggs that get through the quarantine process.

Worm egg test the imported sheep 14-days after drenching to check that there are no worm eggs present.

When it comes to lice, the greatest risk when introducing sheep into an enterprise is they spread to lice-free sheep already present.

"Always assume sheep purchased or returning from agistment are lousy, regardless of their treatment history," she said.

"And while the lowest risk of introducing lice is to shear and treat immediately on arrival, this will incur a significant cost from discounts for premature shorn wool."

Dr Maxwell said eradication of lice on the first treatment fails in more than one-third of attempts.

"Lengthy isolation of the brought in sheep and strict attention to detail is critical," she said.

"Isolate brought in sheep and choose from three options according to wool length.

"Less than six-weeks wool treat immediately with product and method to suit time off shears.

"Greater than 10 months wool I suggest shear and treat as soon as possible and between six-weeks and 10 months wool, isolate securely and treat as soon as feasible."

She said if lice need suppressing with a long-wool treatment it will not eradicate lice and suggested using LiceBoss long wool tool to assess the cost effectiveness.

"After that, continue isolation ideally at least for another year after treatment to confirm eradication," Dr Maxwell said.

"Keep in mind some properties can take three years to achieve complete eradication."

She warned split shearing increased the the chance of failure with shearing and treatment of both the new and existing mobs at the same time essential if they are to be boxed together before eradication is confirmed.

For more information go to and search for 'stock introduction and quarantine policies' and and search for 'quarantine drenching'.


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