Benzimidazole resistance in Haemonchus contortus

Benzimidazole resistance in Haemonchus contortus
Peer reviewed


During routine monitoring of sheep involved in a parasite control trial at Ruakura (a comparison of “Integrated Control” (IC) with three drenches administered during the autumn) it was noted that the IC flocks had positive faecal egg counts 14 days after both their spring and autumn drenches. Faecal cultures showed that the egg output on both occasions was 100% Haemonchus. Valbazen (albendazole) at 1.5 x the recommended dose had been used. The faecal egg counts after the spring drench were low initially and were not regarded as a problem. However, over the summer the faecal egg output built up, with lambs showing signs of clinical parasitism before the autumn change to new pasture…

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