Dawbuts Newsletter Nov-Dec 2025
- Matt Playford
- Nov 11
- 12 min read
Updated: Nov 18
It’s been an exciting year so far for all of us here at Dawbuts. As well as our international adventures, we have inducted new staff, built a new lab, introduced novel technologies and techniques and rubbed shoulders with the world’s best and brightest in the field of veterinary parasitology.
But our focus is always on the flocks and herds of Australia. Looking down the microscope, what we see simply reveals what is happening out in your paddocks.
*THM = Take Home Message
Christmas Hours
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International Sheep Veterinary Congress
The last week in October 2025 saw Wollongong, NSW (renamed ‘Woolongong’ for the event, boom boom!) play host to 300 sheep veterinarians from across the globe.
It was heartwarming to meet Sergio, a veterinarian from Uruguay, who looked at me with recognition in his eyes and said “I saw your ParaBoss webinar! Hola amigo! Now I meet you in the flesh!” It is really great to know that the ParaBoss extension messaging is going out to where it is needed, even as far as South America.
Also lovely to meet a group of three Italian vets who came from the island of Sardinia. They didn’t really want to talk shop, but they were keen to share a glass of our local red at the gala dinner. “You should try the Sardinian wine!” they told me.
Highlight of the week was the Techion-sponsored Sheep Parasite Session on Tuesday 28 October. Nick Rolls of Elanco and Brown Besier of BB Consulting in Albany, WA, presented the latest results from 80 drench tests conducted over the past three years. The results confirmed the trends we’d been observing from resistance tests coming through the Dawbuts laboratory.
In summary, resistance has progressed across all the major worm species in sheep since the last national review was published in the Australian Veterinary Journal (Playford 2014). We are now seeing cases of resistance to mectins in black scour worms. Even the ‘new’ active ingredients (in Zolvix and Startect) have had resistance reported at low levels, with barber’s pole worm and brown stomach worm the culprits. Brown stomach worm is also the hardest worm to kill with triple combination products.
The full results will be published soon in the Australian Veterinary Journal.
Matthew Colston of Elanco UK described the difficulty of conducting faecal egg count reduction tests (FECRTs) in that country as they attempt to monitor resistance against monepantel.
Rebecca Farnell of Federation University Ballarat described a LAMP test they are developing to show the presence or absence of barber’s pole worms, while Elouise Bliss of the same research group outlined the use of bracken fern extracts on worms kept in culture in the laboratory (note, before it could be used on live sheep it needs to be carefully treated to take the toxins out).
Serian Evans of Aberystwyth University in Wales told how over-treatment of stock for liver fluke is common there, as producers don’t rely on diagnostic tests. The result is poor control and flukicide resistance.
Matt from Dawbuts presented data from 40,000 mobs of sheep, showing the seasonal distribution of the common sheep worms in the period 2015-2019, compared to 2020-2025.
Spoiler alert. There was a big change! See below for details.
Chief Veterinary Officer of Australia, Beth Cookson described the key exotic diseases currently spreading around the world, including PPR (‘Pestes des petite ruminants’), sheep and goat pox, foot and mouth disease and bluetongue.
Back from Sabbatical
Dawbuts’ principal veterinarians Matt & Sandy Playford arrived back in mid-August 2025 from a year’s sabbatical in Japan.
They lived in a village called Yoshiumi-cho on an island called Ohshima, near the city of Imabari in Ehime Prefecture in Shikoku. It’s only a short distance from Hiroshima and well-worth the trip for the scenic beauty alone.
THM: A year-long learning experience.
Liver Fluke Update
Melbourne University researcher Leah Tyrrel has recently completed a project with cattle producers in Victoria and NSW looking at liver fluke. They found that fine-tuning the autumn fluke treatment can yield material benefits, with one property seeing a 13kg/head weight difference in weaners treated in May (after the end of the fluke pick-up period) compared to those treated in April.
The project also found that resistance to the most popular flukicide, triclabendazole, was common.
A case study on the property of the Connors family who run a self-replacing Hereford herd highlighted the importance of both fluke and worm testing and appropriate product choice for cattle health and productivity. The report is written up on pages 24-25 in Meat and Livestock Australia’s Feedback Magazine, Spring 2025.
Sydney University researchers led by Dr. Nichola Calvani published results from a recent liver fluke resistance study conducted at Gunning, NSW. They also found resistance to triclabendazole, as well as albendazole resistance in liver fluke in goats. You can read the whole paper here.
Fluke control in 2025 is extremely challenging in all classes of livestock due to resistance, snail hosts spreading and varying weather conditions. To find out how to test for resistance and set up for solid fluke control on your property please contact Dawbuts.
THM: Common fluke treatments are no longer effective in most areas. Do a flukicide resistance test and manage stock to minimize loss of productivity.
Appropriate Diagnostic Tests for Sheep, Goats and Cattle
Matt presented on this subject at the International Sheep Vets Conference in Wollongong.
The most recent summary on diagnostic tests for internal parasites of grazing livestock has been published in the New Zealand Veterinary Journal. This includes an evaluation of automated worm egg count machines and an update on methods for worm identification. You can find the article here.
THM: Technology has given us new, convenient tests. Combine these with sound parasitology for optimum livestock productivity.
Update on Resistance in Sheep Worms
The figure below is a summary of resistance to anthelmintics by gastrointestinal nematodes, derived from historical records from Dawbuts laboratory and results presented by Nick Rolls (Elanco) and Brown Besier (BB Consulting) at the International Sheep Veterinarians Congress, Wollongong, NSW 27-30 October 2025.
THM: Resistance to drenches in common worms of sheep is markedly worse now compared to 10 years ago. Control requires knowledge of life cycle and effective monitoring.
2025 | Efficacy |
|
|
Good >95% |
|
| |
OK 90-94% |
|
| |
Marginal |
|
| |
Poor |
|
| |
Bad |
| ||
Haemonchus Barber’s Pole | Teladorsagia Brown stomach | Trichostrongylus Black scour | |
Abamectin | |||
Moxidectin | |||
Levamisole | |||
White / Albendazole | |||
Triple / Q-drench | |||
Zolvix | |||
Startect | |||
Closantel | NA | NA |
External Parasites of Cattle in Northern Australia
The subtropical dairy program provides up-to-date advice and support for dairy producers in northern NSW and Queensland. In this region, internal and external parasites area a huge problem that is not going away.
Once confined to tropical areas, buffalo flies (Haematobia irritans exigua) are extending their range now over-wintering as far south as the NSW Hunter Valley. This is thought to be due to both adaptation to colder climates and a run of suitable weather for them (warm and wet).
Buffalo flies are also very adept at acquiring resistance to chemicals. Topical application of synthetic pyrethroids, which provided 3 weeks protection at the time of registration, are now only lasting a few days.
On top of this, one of the mainstays for long-term protection, diazinon-containing eartags, have now been taken off the market due to a review by the Australian Pesticides and Veterinary Medicines Authority.
You can see more about control of buffalo flies and other subtropical and tropical parasites in this presentation.
THM: There are less products now for control of buffalo flies, which are increasing in number and severity. Effective control relies on a combination of chemical and non-chemical approaches (Integrated Pest Management).
Feedback From our Farmer Clients
We have had a couple of incidents reported over recent weeks where packages have come apart in the mail, prior to delivery to Dawbuts. This has led to serious inconvenience for submitters as some samples were lost or returned to sender. We sincerely apologise for this and have made every effort to ensure that there is no repeat. If you have any further feedback, please let us know by phone or email.
We often field calls asking for worm identification results. Our worm identification service is conducted to industry gold standard, by larval culture, staining and visual differentiation according to parasite larval keys. The only downside is that worms take a week to develop in the incubator, so ID generally takes 8 days to complete.
We are currently looking at technology to assist with faster ID, of course properly validated. Let us know if you are interested.
Please feel free to call us on 02 4655 6464 to discuss your results.
Exzolt for Cattle
One piece of good news for control of external parasites of cattle.
Coopers/MSD have released Exzolt, containing 50g/L of fluralaner. This product is delivered as a pour-on, but a large portion of the dose is licked off the skin by cattle, due to their natural grooming behaviour.
The label claims are for 21 days protection from buffalo fly, 21 days protection from bush tick (vector for Theileria) and 56 days protection from viable cattle ticks.
Many people will recognise fluralaner as the active ingredient in popular dog products that control fleas and ticks. It is in the chemical class ‘isoxazolines’ and so far has had no reported resistance.
Staff Update
Phil Stein (Far Right) continues in his role as Laboratory Manager. Phil is one of Australia’s most experienced parasitologists, with prior experience in CSIRO McMaster Laboratory and Yarrandoo Laboratory (Elanco). A keen golfer, in his spare time Phil runs junior sports programs for football (aka soccer) and athletics.
Andrew Sheehy, our long-term laboratory assistant now fills the role of Operations Manager for Dawbuts. Andrew handles all logistics and supply for Dawbuts, including orders for both worm egg test kits and drench resistance test kits. Andrew is studying for his degree in Bachelor of Scientific Studies at University of New England. He and wife Tara have recently welcomed their third child, a little girl named Willow. Congratulations!
Emilia Trapnell (Top Left) joined Dawbuts last year after a career in human pathology laboratories. Emilia completed a Bachelor of Applied Science at Charles Sturt University, Wagga Wagga, specialising in equine management. A keen horsewoman, Emilia rounds out the lab skillset with characteristic good humour and attention to detail.
Georgia Roberts (R), our newest team member, is studying in preparation for a career as a paramedic. Georgia is multi-skilled, loves horses and provides Dawbuts with a youthful perspective on all aspects of life.
Barber’s Pole Worms on the March!
After testing thousands of mobs of sheep, goats, cattle and alpacas over the past 16 years, we have accumulated a large amount of industry data in the Dawbuts database.
We asked Dr. Ahmad Rabiee, renowned veterinary statistician, to assist us find out how to use this data to assist our clients.
For example, we now know that barber’s pole worms have continued to infect New South Wales sheep over both winter and summer to a greater degree than previously.
In fact, compared to the years 2015-2019, average mob worm egg counts due to barber’s pole worms were about 100 eggs per gram (epg) higher over winter in the 2020-2025 period.
In the past five years (2020-2025), mob average worm egg count in winter across NSW for barber’s pole worm alone has been 300 epg, compared to 200 epg in the same winter period in the previous 5 years
Numbers of barber’s pole worm eggs in mob averages peaked in autumn (March-April), but the mob average peak across NSW in 2020-2025 was 770 epg, compared to only 600 epg in the period 2015-2020.
Several reasons have been suggested for the increase in numbers.
Firstly, weather conditions were wetter in 2020-2025 compared to the previous 5 years, leading to suitable conditions for development of worm eggs to larvae and survival of larvae.
Secondly, barber’s pole worms have developed resistance to all of the available drenches (see summary article above) meaning they are surviving longer even after treatment.
Thirdly, due to their huge genome, barber’s pole worms may be adapting to colder climates, as they have done in places like Canada and Sweden. Less Australian worms are found to be hibernating in the abomasum compared to historical findings.
THM: Barber’s pole worm is now the most common worm found in most parts of NSW. They have different resistance status, biology and pasture contamination to scour worms. Management relies on knowing their weak points.
Vitamin F
Vitamin F is the most important nutritional component of sheep diets. It simply means ‘Food’!
An important message from the Dawbuts database analysis focussed on Body Condition Score (BCS). This simple and repeatable measure can help with management of sheep flocks for reproduction, nutrition and worm control. Many producers across Australia are already familiar with these benefits, thanks to Australian Wool Innovation-sponsored Lifetime Ewe Management extension program.
In short, we asked Dawbuts’ clients to estimate the BCS of the mobs they were testing. Ten years of results, plotted on a graph shows close to a normal curve, confirming that the estimates probably reflect what is happening out in the national flock.
When we looked at the average mob worm egg counts by month in the same 10-year period, the results showed the impact of ‘Vitamin F’.
The results were split into 2 groups.
Body Condition Scores 1 and 2 were Group A, while all scores above this were Group B.
The average mob worm egg counts for each month (average data for 10 years) show that sheep in higher BCS on average stayed below the 300 eggs per gram (epg) level right through the winter. Late summer/autumn worm burdens in this group peaked at 455 epg.
In contrast, average mob score of sheep in lower BCS remained above the 300epg line right throughout winter and peaked in autumn at 630 epg.
This is a reminder that sheep in higher BCS have greater ‘resilience’ towards worms.
Note that this doesn’t make a mob bulletproof and particularly with barber’s pole worms, heavy infections leading to anaemia and death can occur even in heavy sheep.
Increased protein in the ration/pasture also improves resilience.
THM: Select sheep for resistance to worms. Feed sheep for resilience.
Submission Form Changes
You will notice some changes to the Dawbuts submission form. There are now separate entries for ‘mob’ and ‘paddock’. This is to allow producers to not only track mob worm egg counts, but also to assess pasture contamination of each paddock on a property.
For more information on how to use this information effectively, please contact Dawbuts.
THM: Record both mob and paddock to allow you to track pasture larval contamination.
Sheep Blowfly - Chemical Rotation Caution
There has been some confusion over the years regarding the correct approach to use or manage active ingredients to treat parasites.
Rotation or Combination?
Information on this subject has come from:
computer modelling,
results from the field and also from
long-term trial work conducted by research institutions.
To get further clarity on this, I discussed the issue with Dr. Narelle Sales of NSW Department of Primary Industries, directly after her presentation on sheep blowfly chemical resistance at the International Sheep Vets Conference in Wollongong.
Narelle is a wealth of experience on this topic, leading national insecticide resistance surveys and collaborating with some of the great brains of the subject such as Dr. Gary Levot of NSW and Dr. Brian Horton of Tasmania.
In short, despite the evidence showing that combinations are the best way to gain efficacy and slow resistance in internal parasites (stomach and intestinal worms such as barber’s pole worm, brown stomach worm and black scour worms), the opposite is true for sheep blowflies.
With sheep blowfly, recent modelling results confirm that rotation is still the best strategy. Combining chemicals usually selects for resistance faster.
One exception was highlighted by Dr. Nick Rolls of Elanco, who conducted research on dicyclanil resistance in sheep blowflies with Adjunct Professor Andrew Kotze of CSIRO (currently University of Queensland). Their studies showed that rotating between dicyclanil and imidacloprid gave faster resistance onset to dicyclanil than simply using dicyclanil alone.
The suggestion is that it is better to alternate with spinosad or ivermectin (jetting fluid) for fly control to slow down resistance (see summary slide below).
This is an important tip, as dicyclanil resistance has progressed in some places (notably northwest of NSW) to the extent that even the high dose formulation (65g/L) now only gives a bit over a month’s protection from flystrike. When introduced over twenty years ago, sheep producers could rely on 18 weeks protection from the standard dose (50g/L dicyclanil), but this is no longer the case.
THM: Rotate fly prevention chemicals to keep them working. But don’t use imidacloprid in rotation with dicyclanil (or in the same year for lice).
Sheep Blowfly Vaccine
In other developments for sheep blowfly control, Edward Kerr of CSIRO Brisbane gave us an update at the ISVC in Wollongong on vaccine research. The vaccine directed at the peritrophic matrix in the gut of the fly larva actually works! But only in the lab.
When used in live sheep trials, the results were disappointing. This has led Ed to look at ‘packaging’ the antigens (glycosylation) to ensure a better immune response. The possibility of a working vaccine against sheep blowfly seems close, so we wish Ed and his team all the best with the next phase of his research.
Videos on Dawbuts website
Head to the Dawbuts website (www.dawbuts.com) to see freshly-loaded videos on control of parasites in sheep, goats and cattle, as well as instructions on how to take and submit samples for laboratory testing.
Christmas and New Year
We wish you all the best for Christmas and the New Year, plus any and all other holidays and milestones you wish to celebrate!
Sandy, Matt, Phil, Andrew, Emilia, Wendy and Georgia
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