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New South Wales worms, flies and lice update - April 2021

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






Central West LLS

Condobolin: Hanna Dobell, DV (

Recent WormTests conducted in the Condobolin Region have shown high worm burdens with evidence of barber's pole worm present. Some very high WormTest results were recently found following a disease investigation in young stock three weeks post drenching. In this case it is unknown whether a management error has occurred, or drench resistance is present on this property. DrenchChecks and DrenchTests will be used in future on this property to assist in this area.

Worm management is multifactorial, some important points include;

  • Don’t drench unnecessarily — use WormTests  to determine if you need to drench or not.
  • Follow label instruction for treatment and storage.
  • Calibrate and dose to the heaviest animals in the mob.
  • Use an appropriate drench — generally use short acting combination drench groups (two or more drench groups) that are effective on your property.
  • Use appropriate grazing management — prepare low worm risk paddocks for susceptible stock.
  • Know the effectiveness of drenches on your property: do a DrenchCheck at the least, but ideally a DrenchTest.

Coonabarabran: Kate Atkinson, DV (

Sheep producers in the region are still seeing production losses and deaths particularly from barber’s pole worm. Regular worm egg counts (WECs) remain a vital management tool for monitoring these burdens. Drenching based on WEC results not only prevents production losses but also eliminates unnecessary drenching and cost.

The spring and summer weather has likely been favourable for Ostertagia development in cattle. Weaner cattle are particularly susceptible to worm burdens and this is compounded during weaning time when stress causes immunity to be further compromised. Weaners should be drenched at weaning time then moved to a clean pasture. Combination drenches are also recommended for cattle (as with sheep) to reduce the development of resistance, particularly to macrocyclic lactones (ivermectin, moxidectin etc) which tend to be overused.

Worm testing in cattle is slightly different to sheep as WECs are less indicative of worm burden as cattle get older. Testing for worms in cattle ideally involves WECs as well as a blood test for pepsinogen (indicates abomasal damage from larvae). Worm burdens are therefore interpreted with consideration of both these results. In addition, monitoring of cattle weights is a useful tool to indicate potential production loss associated with worms.

Forbes: Nik Cronin, DV ( and Belinda Edmonstone, DV (

Producers are strongly encouraged to use WormTests as an incredibly useful tool to be monitoring worm egg counts in their various mobs of sheep at this time. WormTest results for our area are showing as expected that barber's pole worm is an ongoing problem, but also that scour worms are present.

WormTests can also be used to monitor the general effectiveness of drenches on your property. Conduct a worm test on a mob of sheep, and where a drench is required then conduct a second WormTest 14 days after the drench is given — this procedure is called a DrenchCheck. Worm eggs persisting after the second drench are a cause for concern and indicate a level of resistance to the drench that was used.

Recently an investigation into mortality in young sheep who had only very recently been drenched showed a high worm egg count — unfortunately drench resistance appears to be a significant issue on this property. Conducting a DrenchCheck each time you use a new drench type can pick these problems up earlier.

It is very easy to conduct a WormTest, and the results may tell you that a drench is not required, saving you money and time, as well as minimising the use of drench chemicals and potential development of resistance. We have WormTest kits stocked at all our Central West Local Land Services offices.

Nyngan: Kelly Wood, DV (

With the recent drop in temperature that allows larvae to survive longer on pasture, and the heavy rainfall a few weeks ago that is likely to have resulted in many worm eggs developing to larvae, all producers should be planning to conduct a WormTest on their sheep by the end of the month. Most producers are either lambing or joining spring-lambers at the moment, which means that there is a high proportion of ‘at-risk’ stock in the district. At-risk animals have a reduced immunological ability to moderate their own worm burdens, due to either physiological stress, such as lambing ewes or joining rams, or immune system immaturity in animals less than 18 months old. Not only are these animals at a greater risk of suffering health complications as a result of worms, they drive higher levels of pasture contamination which then exposes other stock to greater worm burdens.

The recent seasonal change means that selecting a larval culture on your WormTest is especially important as the proportion of black scour worms often increases in our district with cooler weather, which reduces the drenching threshold for most classes of stock, however, more summer rain could have built barber’s pole worm; only a culture will tell you the situation on your property. The mild summer we have had with bigger pasture loads to shelter worm larvae may mean that pasture spelling will have been less effective this year and a pre-lambing drench and close monitoring with WormTests will be critical for autumn lambers this season. For spring lambers, strategies for paddock preparation such as smart grazing, rotational or mixed grazing, or sowing paddocks to crop should be implemented now with the understanding that larval burdens on pasture are likely to be higher this year and may remain so over winter.

Finally, producers with autumn-drop lambs should be starting to plan for undertaking a DrenchTest at weaning. Central West district vets have 10 different drenches available for testing and will run the program with producers only having to pay for the WormTests. If you are interested, please contact your local district vet for more information.


Murray LLS

Albury: Eve Hall, DV ( and Jess Kopp, Charles Sturt University

The last month has likely seen the last of the warmer weather around the Albury region with many areas experiencing the first frosts of the year. We are just starting to see the first few lambs on the ground. Since the beginning of April, we’ve experienced a wide range in temperatures, from as high as 30.4 down to 3.0 degrees C. As the temperatures continue to trend lower it is important to maintain worm management strategies and not become complacent because the larvae that hatched earlier will live on the pastures for months to come.

The three most common worms to affect sheep and goats in this area are black scour worm (Trichostrongylus spp), brown stomach worm (Teladorsagia circumcincta) and barber’s pole worm (Haemonchus contortus). These are largely unaffected by frosting. It is true that a small number of surface-dwelling larvae may be killed by the cooler temperatures and freezing events, but the main reservoir of infectious larvae will be protected by grass cover and ground warmth. This is especially true after the cooler summer temperatures and higher-than-average rainfall the region experienced in February. These conditions have promoted fast growth of pasture right up until these last few colder days. Although it is exciting to have pasture cover at this time of year, this extra growth has provided the perfect habitat for worm larvae. Inspecting your stock for clinical signs, including scouring and bottle jaw, remains important throughout winter, but can’t replace a WormTest to indicate the best time to drench. Low to moderate worm egg counts (WECs) have been recorded across the district, indicative of the regions’ commitment to parasite reduction. WECs and pre-lambing drenching should be high on the agenda for pregnant ewe mobs, with a ewe’s immunity against worms waning in late gestation and young lambs being especially vulnerable. A DrenchCheck can also be used to ensure that the drenching is effective. This involves performing WECs 14 days after drenching to ensure worm egg numbers have dropped significantly.

Producers should also keep a watchful eye out for covert fly strike (cutaneous myiasis). Although the frosty weather will have significantly decreased fly numbers from an excessive fly year, covert strike (small, less noticeable strike) is still a possibility weeks after the initial strikes may have occurred. Producers should be aware of the observable signs of strike such as, disturbed wool, darker areas of wool or down or unwell animals.

Overall, it has been a great start to autumn! Happy lambing.


Berry: Evelyn Walker, DV (

Worm egg counts (WECs) continue to be high around the Southeast Coast NSW region —encompassing the Shoalhaven and Illawarra Shires. Sheep and goats are showing mostly barber's pole worm at the moment with some black scour worms about. Beware that not all sheep and goats will show the classic signs of bottle jaw—fluidlike swelling under the jaw. The best way to detect early worm burdens is to monitor your flock with regular WECs. In this area, I recommend every six to eight weeks minimum due to the conditions conducive for larval survival around here.

Lately, I have noticed that some producers have continued to use the same single-active drench products over and over again. This practice can speed up drench resistance, meaning that the product will eventually no longer work on your sheep or goat worms. In fact, I have seen drench resistance develop in a sheep flock after using the same product on 5 separate occasions. Rotation is particularly important when you have used a long acting product or have just finished using a low worm-risk paddock, but ideally effective multi-active compounds should be used to slow drench resistance. Ensure you look at the active ingredient/s of your drench products, not just the brand name. Don't limit yourself to what's left on the shelves at the local ag store. You can have products ordered in that suit your management and your flock needs e.g. a chemical with active residual against barber's pole worm; an effective product that has a short withholding period because you intend to sell soon; or even a product that you want to use that is safe on dung beetles.

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