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New South Wales worms, flies and lice update - March 2019

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






Central West LLS

Coonamble: Jillian Kelly, DV (

The Coonamble district remains dry and worm burdens, on the whole, remain low. Stock numbers have reduced significantly since Christmas as people destock heavily.

Interestingly, while I had a Charles Sturt University veterinary student on practice rotation recently, we did a post mortem on a single dead animal—he was a lamb that had gotten into the wrong mob and subsequently become a shy feeder, had done poorly and died. He had a worm egg count of 1200 eggs per gram (epg) which was the highest worm count I've seen in the Coonamble district for several years. I was concerned there might be more worm activity than we had realised on this farm, and undertook worm egg counts on the different mobs. The mob counts were all low (below 60 epg). This demonstrated the effect that stress and poor nutrition can have on worm burdens and worm egg counts. This is not only true for sheep but cattle as well.

If you have sheep or cattle that are doing it tough in stressful feedlot situations, for example, mobs too big, mobs containing animals of varying body weights, or mobs that are nutritionally underfed, they could be contributing to worm burdens. Drenching is not the number one solution—fixing the underlying issue is most important.  

Forbes: Belinda Edmonstone, DV (

Conditions continue to deteriorate in the Forbes area of the central west LLS as producers anxiously wait for the autumn break. There have been very few worm tests performed in the last month. The counts have been very low and have not indicated that a strategic drench is necessary. However, every property is different and producers are encouraged to worm test to determine, in particular, if a pre-lambing drench is needed.

Nyngan: Erica Kennedy (

The Nyngan district, like many others, continues to experience severe drought conditions with little to no ground cover and temperatures in the mid-thirties. There have not been high sheep worm burdens in this area for well over a year, and this will continue to be the case until some decent rainfalls.

Disappointingly, I am seeing producers yarding and drenching stock as a routine seasonal practice. With prolonged drought conditions and low worm burdens, drenching with water would probably be just as effective, a heck of a lot cheaper and not contribute to drench resistance!

Producers who are seeing sheep that are pale, going down when being moved or looking dull should speak to their veterinarian and get a diagnosis before drenching unnecessarily; do a WormTest.

Riverina LLS

Young: Eliz Braddon, DV (

Only 8 worm related tests have been run so far this March, but the trend of last month is continuing with barber's pole worm the dominant species in most worm egg counts and larval differentials. In most mobs, the average is running quite low at 100–360 eggs per gram (epg) with a range of 80–400 epg in the majority.

In a couple of disease investigations, worms played a role in impacting on the immunity and health of the animals. A mob of cattle had a worm egg count of 360 epg with a worm typing of 4% Haemonchus (barber’s pole), 22% Trichostrongylus (black scour) and 72% Cooperia (small intestinal worm) while an ill thrift and mortality investigation of a mob of recently introduced weaner lambs, identified a count of 1200 epg. 

The results of these investigations are a timely reminder that purchased sheep should ideally be isolated in a small paddock on arrival to ensure that any 'passengers' are left behind in a known spot, and of course, are quarantine drenched on arrival at the destination property.

South East LLS

Yass: Alexandra Stephens, DV (

Pasture conditions are much drier this month. Worm egg counts have been low to moderate, and all have shown barber’s pole to be the vastly dominant worm. With pastures browning off at the end of summer, it is important that the second summer drench is completely effective against barber’s pole worm, and that consideration is given to implementing pasture rotations. It will also be essential to ensure adequate protein intake to maintain immunity against worms, particularly in the weaners.

A few ‘DrenchChecks’ have been conducted this month. These checks provide a very valuable assessment of drench efficacy on the current parasites present on the farm, but in a few checks the samples were taken either too early or too late. For accuracy, faecal samples need to be taken within the specified timeframe of 10 to 14 days after the drench is given. On one property the DrenchCheck showed substantial barber’s pole resistance to ivermectin. Post mortem results on another property showed likely resistance to a closantel and ivomec combination.

Fluke has been detected in cattle on a few properties this month using the blood ELISA test. On properties that have ongoing fluke issues, cattle pick up fluke when they selectively graze around greener fluke-prone soaks, particularly during a long dry summer. These cattle present with obvious weight loss and / or bottle jaw, and need to be treated with a product such as triclabendazole that kills immature as well as mature fluke.

Western LLS

Bourke: Charlotte Cavanagh, DV (

With no rain to speak of across the Western area worms are not presenting issues for producers.

Over the last couple of months, there have only been 3 or 4 WormTests submitted by producers, all with results of zero eggs per gram (epg).

Worm egg counts have also been requested as part of sheep ill thrift or mortality investigations and the highest average count was 40 epg.

Producers are still drenching in response to scouring and then, when the scouring continues they contact the veterinarian. Causes of scouring have been identified as salmonella, acidosis, and sometimes coccidia in feedlot situations, rather than worms.

If drenching is being considered, do a WormTest first, as worms may not be the problem. If drenching is indicated, choose an appropriate combination drench (or concurrently use more than one drench) with at least 4 highly effective components—one of these, if not two, should be monepantel (Zolvix®) or derquantel (Startect®).

The weather is cooling down now with days in the mid to high 30s, and starting to suit larval survival, but with no moisture around this should not be a problem.

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