Paraboss News - October 2020 - Feature Articles
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Australia's resource for control of worms, flies and lice in sheep,
and worms in goats
Ever had the seven-year itch?
Scabies (also known as the seven-year itch) is a contagious skin infestation by the mite Sarcoptes scabiei. The most common symptoms are severe itchiness and a pimple-like rash. The mites burrow into the skin to live and deposit eggs. Occasionally, tiny burrows may appear on the skin.
In a first-ever infection, the infected person will usually develop symptoms within two to six weeks. During a second infection, symptoms may begin within 24 hours. These symptoms can be present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline. The itch is often worse at night.
Scratching may cause skin breakdown and an additional bacterial infection in the skin. Crusted scabies is a more severe form of the disease. Infection in other animals (such as dogs, foxes and wombats) is typically caused by slightly different but related mites and is known as sarcoptic mange.
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Sheep are most worm susceptible at lambing and weaning
Whether you’re lambing or weaning in spring, these sheep are likely at a high risk of worm infection right now. As our WA correspondent and eminent parasitologist, Brown Besier, pointed out in the latest state outlooks, “Worm control is especially important for current-year lambs, which are now at the most worm-susceptible time of their lives.”
Early-drop lambs in southern Australia that have already been weaned should have regular monitoring until their first summer drench to identify rising worm burdens before they become a bigger issue. Late-winter or spring drop-lambs in southern Australia that are still to be marked probably don’t need a drench at marking unless they are not growing as well as expected. In summer rainfall areas they may need drenching if the lambing paddocks have not been prepared for low worm-risk. In either case, a worm egg count of their mothers just prior to marking is a good guide—if the ewes are high enough to need drenching then the lambs could also benefit from a drench, and then monitor again between marking and weaning.
In summer rainfall areas, if ewes and lambs need drenching at marking, consider the preparation of a low-risk lambing paddock next year (start six months in advance) to help alleviate the issue. But right now, weaning paddocks for summer rainfall areas should be being prepared.
Planning your fly treatments for maximum effect
A good season for sheep is also a good season for parasites! With things warming up and the wet weather in some regions, fly populations are beginning to boom. Some producers may now be dealing with flystruck sheep if wetter conditions have favoured fly population build up and made sheep more susceptible; district vets from the Murray region of NSW noted an unusually high number of flystrike reports even through winter.
FlyBoss has a number of tools for predicting and planning against periods of high flystrike risks. These can help you to understand what your likely flystrike risk will be and help make decisions about when to take preventative action.
If you crutch and shear on a regular schedule, the online Optimise Treatment Tool can be quickly used to determine when to apply a treatment to ensure that you’re getting the best return on your investment. The new Flystrike Risk Simulator will provide the same information, but it is a downloadable program (for both Windows and Macs) and has the added benefit of allowing you to see how breech changes from breeding could reduce the breechstrike risk in your sheep. This is particularly relevant now if you are about to mark lambs as you can breech score a sample of about 50 lambs and use this information in the Flystrike Risk Simulator.
With summer on the way, it’s time to get on top of your flystrike management plan before you’re dealing with a bigger issue.
Try out the Flystrike risk tools.
Buy in sheep, but don’t buy in lice
Many producers are considering bringing in sheep as pasture growth benefits from a wet spring. Our Queensland contributor and parasitologist, Maxine Murphy, discussed the risks of buying in from worm hotspots in our September State Outlooks, however the risk of a lice infestation can be just as great when bringing in new sheep.
In fact, because lice can be tough to spot for up to six months after shearing or a failed treatment or a new infestation, it’s easy to think they are not there. However, it is best to assume that all brought-in sheep are lousy until proven otherwise to avoid expensive and time-consuming lice treatments in your existing lice-free sheep.
When bringing in small numbers, shearing and treating is ideal to remove either a possible, but undetectable, lice infestation or an obvious lice burden, but this may not be the ideal choice when purchasing a larger mob of sheep. At the end of the day, keeping lice out is all about what level of risk you’re willing to accept.
LiceBoss has developed the LiceBoss Treatment Guide so you can explore your lice treatment options and pick one that works for you.
Identifying drench resistance in goats
As goat producers begin to plan summer drenching, it’s important they consider whether the drenches to be used are still effective. Treating worms with a drench they are already somewhat resistant to can make drench resistance worse, resulting in ineffective worm control with the potential for production loss, deaths and a need for even more drenches.
While the Drench Decision Guide can assist in determining whether or not to drench, ensuring that the drench is doing its job is a matter for a DrenchCheck—the use of a WormTest just prior to a drench and then a follow up WormTest 14 days after the drench to assess the impact it has had on worm egg numbers. If your drench is no longer working effectively, this is due to the worms on your property developing resistance.
Drench resistance is the ability of a worm to survive a drench that should have normally killed the worms. It’s a genetic characteristic in the worm, and each time a drench is given and drench-resistant worms survive and susceptible worms die, it increases the proportion of the worm population that is drench-resistant.
As long as drenches are used, resistance will gradually increase, but through careful management and good practices, the development of drench resistance can be slowed down considerably.