Sheep Drench Study Reveals Resistance Problems
August 30, 2013

The first national Australian drench-resistance study in sheep for nearly 20 years has uncovered unexpectedly high levels of resistance to commonly used active ingredients in sheep drenches. 
 
The study used parasitology laboratory data from 390 fecal egg count reduction tests conducted on properties across all Australian states. 
 
The results of the study showed a 54-percent prevalence of drench resistance across Australia to moxidectin, a leading sheep drench active ingredient. 
 
There was also a 96-percent prevalence of drench resistance to benzimidazoles and levamisole, the oldest drench classes. 
 
A co-author of the study said the results showed the number of viable drench options sheep producers had available was becoming very limited, very quickly. 
 
Reprinted in part from The Land