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Tasmania worms, flies and lice update - March 2021

Tasmania WormBoss Worm Control Programs

Tasmania WormBoss Drench Decision Guides

Sheep

Goats

Sheep

Goats

Perth: Paul Nilon, Nilon Farm Health (pandonilon@bigpond.com)

Most of the state is quite dry. Bothwell and Derwent Valley have no green left, save for irrigated paddocks. If a second summer drench has been delayed, drying conditions will help you. Those who have given the second drench should monitor closely and consider an autumn break drench (there may be a widespread rain toward the end of the month and into April).

An additional issue is the number of cases of Haemonchus (barber’s pole). These are occurring on (mostly) irrigated paddocks. Producers with a barber’s pole diagnosis need to consider additional worm control measures in the late autumn. If you watch the email for incoming from Sheep Connect or Pinion Advisory, there is a seminar at Campbell Town 30/03/21 to discuss this.

Fluke Drenches: Since the mid 1980’s the gold standard product for fluke control was (is) triclabendazole (TCB, including Fasinex™ and similar products). You may remember that in the middle of last year I wrote about two clients’ who received lambs carrying fluke highly resistant to TCB. These buggers were seen to migrate from the cut surface of a PM liver towards a drum of TCB to have a drink at the bar!

I have no idea of how widespread TCB resistance is. Consistent users (those that give therapeutic and strategic drenches) may well have a problem. Last year’s wakeup call urges that we check efficacy with a before and after fluke sedimentation test. Do a fluke egg count 28 days after they were drenched (and preferably a count on the day of drenching as well). The reason for waiting 28 days is that it can take this long for all the eggs left inside the liver (the bile ducts) to clear from the system.

TCB has the significant advantage of being the only product that kills fluke at all 3 stages, although only down to two- to four-week old fluke, not to the youngest possible early immature fluke. The only better option is a combination of triclabendazole with oxfendazole, with a claim down to two-week old fluke. Alternative products are less effective for early stages; they only kill adults, or immature stages down to about six to eight weeks. This means that if you need to drench therapeutically, you may need additional drenches. For those that give an autumn strategic drench it needs to be delayed by some weeks.

The alternative products are:

  • Oxyclozanide: (Nilzan, in combination with levamisole): ESI 14 days. Kills mature fluke only.
  • Closantel: Any number of brands singly or in combination with round worm actives. It kills fluke down to about six weeks of age, with high efficacy against adults. It also has sustained activity against barber’s pole. ESI for standalone is 60 days.
  • Other white drenches (e.g. Albendazole): these have variable activity against adult fluke. There are two issues: firstly, the variable is quite variable and, secondly, I don’t know if resistance to TCB confers resistance to BZs (they are closely related). I would only take this option if you don’t have a fluke problem to solve.
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