Click here to hear Dr. Tim Elliott talk about the importance of quarantine drenching on your farm.

Every time we drench, we select for resistant worms as the worms that survive the

drench pass on the resistant genes to their offspring. If we use the same drench

continuously, drench too often or under dose the animals, the number of resistant

worms in the population will increase. Worm management programs are vital to

prevent this from happening.

One of the quickest ways to get drench resistant worms onto your farm is with a truck!

Any sheep arriving onto your farm that were not born and grazed on your farm can

carry parasites that may be resistant to drenches and can be the downfall of your

parasite control programme. When sheep arrive on your property, the assumption

must be made that these sheep are carrying parasites that may be resistant to a variety

of drenches and must be treated as such.

A protocol to follow whenever any outside sheep or sheep returning from agistment

arrive on your farm should be as follows:

1.

When the sheep get off the truck and enter the yards, they should be drenched with at

least 4 broad spectrum drench groups. Note: If the animals are unfit to be drenched

straight away, they should be given access to water and hay in the yards for 24 hours to

allow them to recover before the drenches are given. See Tables 1 and 2 in regard to the

types of drenches that can be applied depending on the situation.

2.

Once the sheep have been drenched, they need to be left in the yards (preferably on

dirt) for 1-3 days to allow for the worm eggs that have been produced by the worms

prior to drenching to be deposited on the paddock. Sheep need access to feed and water

during this time. If the animals are kept in a holding paddock with grass, avoid grazing

this paddock with sheep for a minimum of 3 months, but ideally longer.

3.

After the sheep have been in the yards for 1-3 days following drenching, they should be

placed onto a paddock that has been recently grazed, preferably by young sheep from

the farm. This is so the new animals will become infected with the farm’s worms

and dilute out any worms that may have survived the quarantine drenches and reduce

the risk of any multi resistant worms (worms that are resistant to multiple drench

groups) being deposited onto the pasture.

4.

Fourteen days after the sheep have received the quarantine drenches, a Faecal Egg

Count (FEC) needs to be conducted on the new arrivals to ensure that the quarantine

drenches were effective. If any worms have survived four or more different drench

groups, they are very resistant, and the animals need to be drenched again. See Tables

1 and 2 regarding which drenches can be used if this occurs, but it will depend on the

drenches that were originally given to the sheep.

5. If the sheep have come from a known liver fluke area and were drenched for liver fluke

as part of the quarantine drenching, collect samples 63 days later and test for liver fluke

to ensure that the infection has been removed.

Dr Tim Elliott is a large animal scientist with over 15 years’ experience. Tim has a particular interest in production animal parasitology and drug resistance. Tim’s work has been published in internationally renowned journals and has presented his work around Australia for scientific audiences and farmer groups.