Update on Parasite Control in Small Ruminants 2006

Addressing the Challenges Posed by Multiple-Drug Resistant Worms

Abstract

Gastrointestinal nematode (GIN) parasites are the single most important health problem of sheep and goats. Traditionally, parasites have been controlled by frequent administration of anthelmintic drugs. However, the emergence of multiple-drug resistant parasites now threatens this paradigm of control and new approaches are required.

Anthelmintics can no longer be thought of as an inexpensive management tool to be used as needed to maximize animal productivity. Instead anthelmintics must be thought of as extremely valuable and limited resources that should be used prudently. In response to this changing paradigm of anthelmintic use, new recommendations for parasite control have been proposed. The basis of this approach is to use the knowledge we have about the parasite, the animal, and the drugs to develop strategies that maximize the effectiveness of treatments while also decreasing the development of drug resistance. The term "Smart Drenching'' is often used to describe this approach to worm control. Due to the complexities ofinstituting such a program, successful implementation will only be possible with the help and active involvement of small ruminant veterinarians and other animal health professionals. Additionally, new innovative schemes using novel and sustainable approaches must be implemented. There are a number of new non-chemical technologies that will become increasingly important in GIN control programs both in the short and long term future. However, it is highly likely that any new technologies or developments in non-chemical GIN control methods will be less effective than chemical control has been (prior to emergence of drug resistant parasites). Therefore, as novel non-chemical control modalities become available and widely applied, anthelmintics will still be required for life-saving therapy when control fails. Unless veterinarians take an active and leading role in the education of small ruminant owners and help to implement these new approaches to parasite control, there may be no effective anthelmintics remaining when that time comes.