Anthelmintic Resistance in Equine Nematodes – A Review on the Current Situation, with Emphasis in Europe

Since the introduction of the last equine broad-spectrum anthelmintic group in the 1980’s, the investment in new drugs to control horse’s parasites did not result in new advancements. These drugs allowed a very effective and extensive control of equine nematodes through successful interval dosing programs, firstly introduced in the 1960’s. However, the widespread and indiscriminate use of anthelmintics in these intensive treatments have led to increasing resistance in the major equine nematodes. Reports of reduced effectiveness are virtually worldwide and repercussions in livestock production farms have already been seen. Based on recent questionnaires about horse farm practices, preventive measures and international recommendations, it is clear that most of them are still not being widely implemented. It is also clear that these recommendations are outdated and new approaches must be considered to correctly tackle this rapidly evolving issue in horse management, as more accurate diagnostic methods are currently available, such as Mini-FLOTAC. This article intends to do a general review of the history and current situation of anthelmintic resistance in horses, with emphasis in Europe, as well as, how to diagnose and delay or even prevent its further development, mentioning new methods of diagnostic and directions in which to develop research.