Nutrition & Animal Health

Resistance to new drench a ‘wake up call’

Sheep Central, July 4, 2014

The first confirmed Australian case of worm resistance to a new sheep drench, monepantel (Zolvix), has been reported by NSW Department of Primary Industries (DPI) and Local Land Services (LLS) in a wake-up call to livestock producers across the country.

Severe resistance in small brown stomach worm, Teladorsagia spp., and emerging resistance in black scour worm, Trichostrongylus colubriformis, have been confirmed in goats on a central west NSW farm.

DPI veterinarian, Stephen Love, said while tests confirmed that monepantel was highly effective against barber’s pole worm, Haemonchus contortus, the case was an alert to livestock producers to be on the ball when it comes to managing drench resistance.

“Available since spring 2010, monepantel is our newest sheep drench, which makes the confirmation of resistance a big issue for local livestock producers,” Dr Love said.

“Management of worms to slow down the development of drench resistance is critical to the biosecurity of our major livestock industries.

“It’s not just a concern for goat and sheep enterprises – recent cases show that resistance of cattle worms to drenches is also an issue.”

Dr Love said integrated parasite management helps avoid over-use to prolong the life of drench actives.

“We advise regular worm egg count monitoring, DrenchChecks or faecal worm egg reduction tests, grazing management, breeding and feeding animals to make them less vulnerable to worms and maintaining some worms in refugia, which are not exposed to drenches.

“Quarantine treatments on newly-introduced livestock can be used to ensure those animals aren’t bringing resistant worms onto the farm.”

While on-farm best practice worm management remains the key to slowing down the development of resistance, this case has highlighted the significant role played by DPI, LLS and Novartis in supporting livestock industries.

Potential resistance was first identified following routine monitoring by the goat producer and advice was sought from Forbes-based LLS veterinarian, Belinda Edmonstone, who immediately followed standard protocols and set up a DrenchTest.

Samples tested by DPI’s Elizabeth Macarthur Agricultural Institute and Novartis found potential resistance and subsequent testing in sheep by Novartis confirmed the resistance.

Monepantel is registered only for use in sheep, but can be used on goats under veterinary prescription in special circumstances.

Source: NSW Department of Primary Industries. Best practice worm management information is available on the Department’s website here

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