Untangling conflicting messages

Optimal approaches for controlling internal parasites of cattle in the age of drug resistance

Abstract

Anthelmintic resistance in gastrointestinal nematodes of cattle has been worsening over the past 2 decades and is now a global problem. Though the problem was originally seen primarily in Cooperia, which is not a highly pathogenic species, we now know that other more pathogenic species have become drug resistant as well. With no new classes of anthelmintics in the cattle product pipeline, we will need to be better stewards of the drugs we have now, as they will need to last us for a long time. Thus, there is a need to use our anthelmintics differently and smarter than in the past. In this paper we present several strategies for improving the sustainability of parasite control in cattle that will both reduce the development of resistance while maintaining good productivity. Furthermore, we should not just assume a drug works or does not work; testing using the fecal egg count reduction test (FECRT) should be performed on every farm. This is the only way to make evidence-based decisions on optimal drug choices. Optimally, the strategies promoted here should have been instituted years ago. However, it is not too late, and the sooner these strategies are implemented widely, the more successful the beef industry will be in controlling parasites both now and in the future.