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New South Wales worms, flies and lice update - December 2020

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






Central West LLS

Condobolin: Hanna Thomas, DV (

Recent WormTests for the Condobolin region has shown high worm burdens. With one test conducted on bought-in sheep resulting in 23,000 eggs per gram. This emphasises the importance of drenching all introductions (including rams) onto your property or doing a 'quarantine' drench. With a quarantine drench it is recommended to use a combination of no less than four unrelated drench actives, with at least one being the newest drench actives (monepantel e.g. Zolvix™ or derquantel e.g. Startect™). Make sure not to mix different drenches unless it is stated on the label. Mixing drenches generally involves up the race with one product then up the race again with the next.

Coonabarabran: Kate Atkinson, DV (

Flystrike continues to have a large impact in the district, with reports of reduced longevity of product efficacy, particularly with dicyclanil (such as Clik™). The Department of Primary Iindustries are currently offering discounted flystrike insecticide resistance testing which can help in decisions around managing flystrike issues along with strategic management.

Drench resistance testing for worms is also still being offered and conducted in region. This provides invaluable information as to the effectiveness of drenches, and for the management of worms in your flock. It should especially be considered for flocks experiencing resistance issues.

Coonamble: Jillian Kelly, DV (

Barber’s pole worm burdens are high on some farms, especially those who do not do worm testing and who drenched routinely through the drought without checking drench efficacy. I have seen clinical cases and deaths from barber’s pole worm on a farm near Gulargambone in recent weeks. Producers are reminded to conduct a WormTest, and ask their local district vet for any relevant anthelmintic resistance data they may have, to help make the best drenching decision. Many producers are seeing flystruck sheep despite application of dicyclanil or cyromazine products. If this is the case it is an absolute must that they treat struck sheep appropriately, as these struck sheep will be harbouring chemical resistant maggots. Producers need to shear the struck area completely leaving a wide margin of at least 5 cm, exploring all tracks where the struck area runs. They need to apply a suitable flystrike dressing product. They then need to take the wool and maggots they have removed from the sheep and double bag it in black plastic and leave it to heat up in the sun, destroying the maggots entirely. While the Coonamble area has turned dry again and is waiting for the promised La Niña rains, producers are urged to consider non-chemical means of flystrike prevention this year, such as an extra crutching or shearing.

Forbes: Nik Cronin, DV (

Harvest continues in our local area, with intermittent rain events being one of the factors drawing things out. Remember these summer storms provide excellent conditions for barber's pole worm infestations to cause problems, so monitoring your stock both by observation in the paddock and conducting WormTests is important. Barber's pole worms are blood feeders, so they cause anaemia, which results in lethargy, weakness and potentially even death. Out in the paddock you may notice sheep lagging behind when being pushed, possibly going down, and there may be a number affected with 'bottle jaw'. This appears as a soft, fluid-type swelling of the skin seen under the jaw, and develops because of low protein in the body — as well as red bloods cells, the worms also remove protein from the blood. Female barber’s pole worms can lay a huge number of eggs; up to 10,000 per day, and when there is adequate moisture and warmth they readily develop to the infective larvae state. With summer storms, like we are currently experiencing, pasture contamination can build up very quickly, and outbreaks can be very damaging. We have not seen any barber's pole worm problems yet, but the best option is to monitor and prevent!

Also remember now is a good time to be considering a first summer drench. In our area it is recommended to conduct a WormTest in advance to determine if a drench is required. However lambs being weaned should always be drenched.

Nyngan: Kelly Wood, DV (

Producers are reporting a lot of issues with flystrike in the Nyngan district, particularly body strike. We are recommending producers think holistically about fly management and not simply rely on chemicals. In order to manage risk, producers are encouraged to increase surveillance of high-risk sheep, particularly following rain events that allow skin wetting for more than two days. Sheep at increased risk of body strike include sheep in 4–6 months of wool, which have the highest risk of fleece rot compared to sheep with either more or less wool. Sheep less than one year old are also at an increased risk of fleece rot, especially if shorn as lambs. Producers may overlook the fact that shedding breeds are susceptible to body strike and the persistence of insecticides on these breeds may be reduced due to the decreased lanolin in their wool.

Once a strike has been identified, it needs to be treated as soon as possible. This is imperative both from an animal welfare perspective and to reduce the fly populations on a property. Treatment should include clipping the struck area with wide margins (at least 5 cm), putting the wool and maggots into a black plastic bag in the sun to kill them completely, and applying an effective dressing that contains a different chemical class to the prevention products used on property.

An integrated fly management strategy also relies on good lice and worm control. Eradication of lice and good biosecurity protocols to avoid reintroduction is important not only from a production standpoint but also to spare insecticides for flystrike. It is important to note that some lice products are now registered for flystrike control and producers need to account for this when rotating chemical classes to reduce fly resistance. The LiceBoss products tool is an excellent resource to aid producers in selecting appropriate short/long wool treatments

Northern Tablelands LLS

Inverell: Andrew Biddle, DV (

Things on the Northern Tablelands of NSW have worsened further over the past month.Rain has been localised and scattered.Current hot dry conditions are unfavourable for worms too.

Those areas still getting rain, where it is a bit cooler on higher elevations, should continue to monitor burdens, and post-drenching keep an eye on drench resistance.

Seasonal lambs are being marked currently. They are a valuable commodity this year and investment in two doses of 6-in-1 are advised. Treat your vaccine kindly; keep it cool (ideally with ice bricks) when out of the fridge, from your resellers door all the way to the marking cradle. The most expensive vaccination is the one that doesn’t work.

Follow-up from Andrew: We have had three days of rain since penning this report. The nice falls have gone some way to get the season back on track. However, my message does not change:Monitor mobs to determine burdens before clinical haemonchosis occurs. Recent rain with follow-up may see our first seasonal peak of clinical barber’s pole worm to coincide with Christmas.

Murray LLS

Albury: Mark Corrigan, DV ( and Eve Hall, DV (, Deniliquin: Linda Searle, DV (

As we move well into December harvest is now coming to a close. Croppers have had a good November despite a few heavy downpours and a few cool days. With the good spring conditions there has been a few black scour worm (Trischostrongylus) issues suspected at post mortem, which were further confirmed by worm egg counts (WEC) in weaned lambs. Producers with affected mobs reported a distinct tail to the mob and occasional deaths. Despite being drenched 6–8 weeks previously, the weaned lambs were found to have high WEC. It was found that the weaners had been put onto a paddock with infective worm larvae after drenching, leading to reinfection and thus the continuing worm issue.

Hydatid cysts were found in a sheep during another postmortem. This was a good reminder for producers to regularly worm all dogs on the property for tape worm and  keep  dogs away from raw offal of sheep. If the cysts are consumed by the dogs, an adult tape worm will develop in the intestine of the dog, producing eggs that, if consumed by humans, can potentially cause a dangerous cyst to form in liver lung and sometimes the brain.

Based on current information from WECs the main worm species we are seeing at the moment is the black scour worm. Currently barber’s pole worm (Heamonchus contortus) numbers are low but it will be one to watch for if there is the predicted wet summer. The last few years there have been fewer ‘summer’ drenches undertaken due to WEC indicating low worm burdens. WEC should be performed before deciding if any summer drenching is necessary.

In the west there has not been many worm issues or WormTests. It is the time of year when we need to be on the lookout for summer weeds, especially in bare areas after rain the growth of heliotrope, cathead and hairy panic can occur. Ingestion of these weeds can cause liver damage which in turn lead to other issues such as photosensitisation and copper toxicity.

South East LLS

Braidwood: Lou Baskind, DV (

The beginning of November saw a large fall of rain across the south east, but things have turned a little drier since then, with rainfall being more spaced out and with smaller totals. In Braidwood we clocked up 112.8 mm for November, which was actually a bit below the 30-year average. By December 14th (the time of writing) the total for December is only 10.6 mm so far. Predictions are still for wetter-than-average all the way through to March.

It is getting warmer, with the max hitting 33.7 degrees celsius on November 28th. But with average daily temperatures still in the low 20s, it feels nothing like the hot and dry of December 2019. However, the slightly higher temperatures, slightly lower rainfall and some windy days have started the summer dry-off and the pasture is changing from green to gold.

Many pastures are not optimally stocked, so grasses are very tall and have gone to seed. Soil moisture has declined over the last month but where pastures have been cut for hay, or even just slashed, there has been enough moisture to allow the growth of fresh green pick.

Cattle liver fluke results: Surveillance by blood testing for liver fluke in cattle (a test that detects antibodies to the fluke parasite) has shown no or low levels of infestation. I suspect this may be accounted for by plenty of grazing options, meaning cattle aren’t being forced into flukey areas. Fluke risk is different for each property and grazing history, so some producers will need to use a fluke drench in their summer program. If you are unsure about your fluke risk, contact your local District Vet for advice.

Sheep WormTest results for Braidwood:

  • A mob of weaners had a count of 1180 eggs per gram (epg) six weeks after a drench was given but movement to clean pastures did not occur
  • A mob of lambs bought in from the Yass area had a count of 580 epg, which was a mix of black scour worm and brown stomach worm, but interestingly no barber’s pole worm
  • A mob of mixed-age sheep last drenched three months ago with a single active white drench had 90% barber’s pole and a count of 640 epg. Drench resistance of barber’s pole to the white drench group is common and the producer was subsequently advised to use an effective combination of two or more drench groups
  • A mob of ewes four weeks after the protective period of a closantel and mectin combination drench had a count of 520 epg, of which 50% were barber’s pole

Despite these counts, all the mobs tested were in good body condition and showed no signs of scouring or weight loss.

Sheep worm summary: Worm numbers are up, but haven’t exploded as much as they might have given the wet and warm conditions. This is probably a factor of good nutrition, pasture length, low stocking rates and effective drenching. With the haying off, if you haven’t given your sheep a ‘summer’ drench yet, it’s time to do it now. Drenching lambs at weaning is also essential as it helps lambs maintain the growth rates required to survive. Follow the principles on the WormBoss page ‘Managing drench resistance’ to help preserve the effectiveness of drenches on your property. If the current warm (not hot) temperatures continue, pastures will need to be spelled for three months to make them safe, so consider that in your grazing program.

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