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ParaBoss News - June 2021 - Feature Articles

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Fast Fact


Of mites and men

Bird mites is the common name for a number of species which feed on young birds. They are found all over the world’s warmer regions, thriving best in moist or humid conditions during spring and early summer. Bird mites live in birds’ nests, where they feed on the blood of birds, but may enter homes and feed on humans when the birds leave the nest.

Their bites can cause severe irritation, but the mites themselves cannot complete their life cycle on a human, typically dying within three weeks without a blood meal from a bird. Dealing with an infestation in homes typically involves removing birds’ nests and preventing mites from entering the building through broken or cracked roofs and eaves.

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Feature Articles

Using long-acting drenches effectively

A long-acting or ‘persistent’ worm treatment is so named because it works over a longer period of time. This helps to kill established worms and infective larvae for up to three months from the date of treatment, depending on the product. There is also a range of mid-length products which work for one to six weeks, as opposed to a typical drench which works quickly before leaving the system.
Persistent products can lead to drench resistance developing more rapidly, as the ongoing exposure more heavily favours resistant worms who survive and reproduce throughout the treatment period. As the effectiveness wears off towards the end of the treatment period, partly-resistant worms are also more likely to survive.

This can be managed by the use of a ‘primer’ drench, a short-acting effective product given at the same time as the persistent product and that contains a different active (ideally a combination). This helps to kill worms that are resistant to the persistent drench up-front. An ‘exit’ drench or ‘tail-cutter’ is similar in that it is a short-acting drench containing different actives, but is given two weeks after the long-acting treatment period to kill any larvae that survived to become breeding adults.

Find out more about using primers and tail-cutters to get the most out of your long-acting drenches via

Choosing the right method for applying a flystrike preventative

While other management strategies – such as breeding for resistance, dag management and strategically timed shearing and crutching – can greatly reduce the risk of flystrike, at certain high-risk times it may still be appropriate to apply a chemical preventative or treatment.

There are a number of options for how to apply a chemical treatment, broadly speaking including jetting, spray-on and dipping. Each has its pros and cons, for example hand jetting can give the most thorough coverage but is slow-going and the effectiveness suffers as the operator begins to tire. Automatic jetting is faster and easier but requires greater set-up and leaves even higher residues. Spray-on products are quick and convenient but are more costly. Lastly there are dips which can treat large numbers at a time but should only ever be used for emergency treatment of fly struck sheep, these require specialised equipment, are wasteful with the product and greatly increase exposure of operators to the chemicals used.

Choosing a method depends partly on the products you wish to use, and partly on the situation in which you’re using the treatment. Making that choice means understanding the advantages and disadvantages, and where each is most appropriate.

Find out more about choosing an application method for flystrike preventatives via


Treating sheep to ensure lice are eradicated

When it comes to lice treatments for sheep, much like a primary school classroom with headlice, there are no half measures – you eradicate them entirely, or you commit to their ongoing management. One sheep missed at shearing or not treated properly can be your undoing, as this enables lice to survive and continue to multiply and spread.

The May edition of ParaBoss News covered the decision on whether to treat for lice. If you’ve decided to treat at your next shearing, why not try for eradication? Lice can only be fully eradicated when treated off-shears or in short wool. Much like flystrike prevention, how you want to apply the treatment will dictate what products are available to you. Long wool treatments are definitely out of the question as complete coverage is difficult and the chemicals can easily miss the lice and therefore survive in the dense and moisture-resistant fibres. You’ll also need to consider whether your lice are resistant to the chemical group and what impact this treatment will have on the development of chemical-resistant flies.

Lastly, biosecurity will be a must going forward to ensure your sheep don’t become reinfested. This means keeping sheep away from potentially lousy strays, shearing and treating new sheep before they are added to the mob, and – if you’re conducting split-shearings – ensuring that the two groups cannot mix! You’ll want to go two full years without finding any lice on close inspection or seeing signs of rubbing before you can consider them fully eradicated, but once you’ve achieved that, the benefits of a lice-free flock speak for themselves.

Find out more about eradicating lice via

A few days of quarantine can save you from years of hassle

It’s often said among the ParaBoss team that the easiest way to end up with drench-resistant worms is to buy them from someone else. When new goats enter the herd, they’re almost certainly carrying worms from their previous property, which will naturally have a different drench resistance profile, meaning they could already be resistant to the actives you’re currently using.

Holding new goats in a yard or a suitable small paddock before releasing them onto your property offers the chance to conduct what we call a ‘quarantine drench’. The process is relatively simple — begin by drenching goats with ideally four unrelated actives, either as combinations or by drenching concurrently (i.e. up the race with one, then up the race again with the next!). Do not mix drenches unless the label says you can or you have specialist advice and remember the restrictions on using products not registered for use in goats, especially dairy goats.

Then hold the goats for around one to three days, allowing any worm eggs to pass from the gut in the quarantine yard, then release them onto a paddock likely to be contaminated with worms from your existing herd — this will dilute the population of any remaining resistant worms. Lastly, conduct a WormTest after 14 days to make sure the treatment was entirely successful.

Find out more about quarantine management for goats at


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from Animal Health Australia

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