The cost of helminth infections in dairy cattle in Europe and the UK was recently estimated at €941 million per annum, due to reduced productivity and the cost of anthelmintic treatment. The negative impact of helminth infections on the livestock industry is amplified by the global emergence of anthelmintic resistance to all three broad spectrum anthelmintic classes licensed for use in cattle against gastrointestinal and pulmonary nematodes and a widely used flukicide, triclabendazole, leaving farmers with reduced options once resistance arises. While resistance in gastrointestinal worms of cattle has received much less attention than in sheep, initial reports concerning reduced drug efficacy of pour-on products were published in 2009 and resistance to all classes is now thought to be widespread.