TSTs: Where are we at and where might we go

Abstract

Drench failure, or anthelmintic resistance, is not a new phenomenon. Since the introduction of broad-spectrum anthelmintics in the middle of last century resistance has commonly developed. As any new active or combination has become available the threat of resistance has not dissipated and each new class or combination simply serves to buy more time before their eventual failure. During this time practices on-farm and the way we have used anthelmintics has largely remained the same, with a focus on whole flock/mob neo-suppressive treatments. Albert Einstein reportedly once said the definition of insanity is doing the same thing over and over again and expecting a different outcome. Without a step-change in how and when we use anthelmintics, resistance to our current suite of drenches is inevitable. With that in mind, the provision of refugia may not prevent the eventual development of resistance, but it can help slow the failure of our existing anthelmintics. A number of approaches and ways through which this can be achieved exist but fitting them into existing systems in a way that is both practical and reliable invariably requires greater consideration and inputs, whether that be time, labour or investment in technology.