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| Worm Resistance | |
| Worm resistance is the ability of parasitic worms causing scour and ill-thrift to survive treatment with anthelmintics. Most sheep farmers rely heavily on the use of anthelmintics to control diseasses associated with these worms due to relatively high stocking rates. | |
Traditionally white drenches (benzamidazoles) have been a problem specifically with resistance from strains of T.circumcincta, but now resistance to levamisole and ivermectin and even cases of triple worm resistance have begun to emerge ie worms that are resistant to all three major groups of anthelmintic. Three major groups of anthelmintic: Benzamidazoles (white drenches) Ivermectins (Ivomec, Dectomax, Cydectin) Levamisole (Exhelm) |
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| In the past advice has been to rotate use of the three groups annually, unfortunately this seems to have facilitated the emergence of multiple resistant worms. It seems that resistant worms have tended to be found on farms that have good control of parasitic disease. | |
| Once you have resistant worms on your premises , it is very difficult to get rid of them, if not impossible. | |
Our best advice to you to avoid the problem is the following: Maintain a closed flock as far as possible*. Double fence your boundary and avoid stray sheep. Quarantine sheep that enter the flock (including purchased tups) and treat them with an appropriate dose of Moxidectin (Cydectin), only releasing them after it has had a chance to work (24hrs) |
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| * Also helps to control other diseases such as Scab, MV, CLA, etc. | |
