SOTA: Parasite Armageddon: The Road to Resistance and Current Strategies for Nematode Control in Horses

Anthelmintic resistance is rampant in equine parasites. Of the only four anthelmintic classes available for equine usage, resistance has been documented to all in important equine parasites. The pharmaceutical industry has not developed and released new anthelmintic classes with new modes of action since the 1990s, and the newest nematocidal class was introduced in the early 1980s. Once anthelmintic resistance has established to a given class in a given parasite species, it remains in the population regardless of the treatment regimen employed. This talk will summarize the current status of anthelmintic resistance in strongylids, ascarids, pinworms, and tapeworms and describe guidelines for resistance diagnosis in veterinary practice. Furthermore, it will describe current options for larvicidal treatment and their expected efficacy levels. The development of strongylid egg reappearance periods following ivermectin and moxidectin over the past three decades will be described, and the implications for parasite control will be discussed. Finally, the talk will outline an evidence-based approach for equine parasite control.