• Introduction • To date, helminth control can be addressed with different strategies, but pharmacotherapy has become the most popular over the last 40 years. This is because an anthelmintic dose can be easily purchased, it does not need complex management practices, the results are almost immediate and at a relatively low cost. Therefore, Control of these parasites is generally through the use of broad- spectrum anthelmintic drugs, which are divided into 3 main groups; benzimidazoles (BMs), imidazothiazoles (IMs) and macrocyclic lactones (MLs). Although this approach was highly successful for a number of decades, we are now experiencing ever-increasing levels of anthelmintic resistance in all drug classes, involving virtually all of the most economically important parasites of all livestock species .Anthelmintic resistance occurs when parasites, usually eliminated by a given dose, suddenly survive the treatment. Since resistance is inherited, the surviving worms will pass their resistance alleles to their progeny

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