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Western Australia worms, flies and lice update - July 2014

Albany: Brown Besier, DAFWA (

WA overview report, July 2014

Lambing will be over on many farms and in full-swing on others, and attention turns to worm control in lambs. Worms will remain a risk for the next few months, while the pasture is green.

Worm burdens in lambs depend mostly on the effectiveness of pre-lambing worm control in the ewes. Worm immunity in ewes is temporarily reduced while lactating, and if they have significant worm burdens they put out larger numbers of worm eggs than at other times.

Lambs: If a pre-lamb drench was given, or worm egg counts showed low burdens in the ewes, chances are that there will be little worm effect on the lambs until they reach 14–16 weeks of age, or later. Worms will be controlled by the usual weaning drench, or for prime lambs not to be weaned then, a worm egg count is recommended.

If there is no information on ewe worm control, worm problems may start earlier—a check of lamb worm egg counts at say 12 weeks will show. (Picking lamb from ewe dung samples from the paddock can be tricky—just a matter of size.)  

Ewes: Scouring immediately post-lambing usually indicates high worm burdens and a drench can be given at lamb marking if needed. In barber’s pole worm risk areas, late-lambing ewes may be at risk due to the development of heavy burdens because of the temporary loss of worm immunity. Ewe deaths due to barber’s pole worm have been seen on a number of farms over lambing time, mostly north of Perth. Worm egg counts will quickly indicate whether there this is a risk.

Hoggets (2013-drop lambs): scouring in this age group at this time of year is almost always due to worms. Usually, a single drench will be effective as the development of worm immunity prevents the further build-up of large worm burdens, other than in genetically worm-susceptible individuals.

Next month: time to plan for drench resistance testing and flystrike management!


Perth region and Central Wheatbelt: Ray Batey, Sheepvet Australia (

Treatments applied at mulesing or marking

Mustering ewes and lambs for mulesing/marking provides opportunity for examination or treatments. In the current season, ewes would be expected to maintain body condition score through lambing, so a quick check to verify this is worthwhile. Evidence of declining condition score might indicate an emerging nutritional or worm problem, particularly if there has not been adequate attention to strategically managing these. 

Lambs often receive a range of treatments in the cradle. In general, giving worm treatments to lambs at this time is not cost-effective, especially in a season such as this. Anthelmintic treatment for very young lambs should be confined to exceptional circumstances on the advice of a veterinarian. However, vaccination against tetanus, enterotoxaemia, CLA and septic arthritis is worthwhile, particularly if followed up with a booster at weaning. Lambs may be given an initial selenium or vitamin B12 treatment, preferably informed by the known selenium status of the flock.

Mulesing is invariably performed pre-weaning in this area and presents a number of challenges and decisions. Whether to perform the Mules operation involves a consideration of the genetics of the sheep, the plainness of the breech and the availability of chemical treatments and monitoring for the period sheep will be in the flock. It should only be performed on Merino type sheep, never on crossbreds, preferably by an accredited operator. Local pain relief and haemorrhage control through the correct use of ‘Tri-Solfen’ is positive for short and medium term welfare but the prolonged withholding period of 90 days requires recording and factoring into early sale of lambs.

Fly prevention treatments should be applied on the skin around wounds, not directly onto the Mules cut, and according to label directions, with appropriate meat or wool withholding or ESI. Only veterinarians may authorise the use of fly-strike prevention other than according to the label. Chemicals should never be used off-label without such authorisation.      


Esperance: Nicole Swan, Swan’s Veterinary Services (

In the last couple of weeks we have had cold, wet weather. The much needed rain has come.
Worm wise this month, we have done counts mainly on one property east of Esperance. These counts have been for ewes pre-weaning. Feed is short due to the late break and the farmer is hoping to wean early. These ewe mobs were, for the most part, drenched with Eweguard in late February onto stubbles. Counts in all mobs were low and ranged from 15–95 epg average. None of these ewe mobs require a drench pre-weaning and will be tested again at pre-summer drench time.

One of these mobs has been drenched with Closantal—both ewes and lambs—and the lambs have been tested to see if there is a high enough worm burden to conduct a Drench Resistance Test. These lambs had an average of only 150 epg. They are now being put on a wormy lambing paddock and will be retested in 4 weeks time. We are hoping that we can get a high enough burden to do a drench resistance test prior to summer. In the meantime, other mobs of lambs will be weaned and drenched pre-weaning. Moxidectin in the form of Eweguard, Weanergard or Cydectin has been used on this property for the last few years. An attempt to do a drench resistance test in 2011 was unsuccessful as we could not get the lambs wormy enough. It is most likely that the weaners will be drenched with a triple combination at weaning and we will wait for results of the drench resistance test for their summer drench option.

If we cannot get a high enough worm burden to conduct a drench resistance test pre-summer then I will recommend that they have Zolvix for their first summer drench. 

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