Multispecies resistance of cattle gastrointestinal nematodes to long-acting avermectin formulations in Mato Grosso do Sul.

The use of long-acting avermectins (AVMs) in cattle to treat infections with gastrointestinal nematodes was common in Brazil until its prohibition by state authorities. The prohibition; however, was rescinded in 2015, but a scientific discussion of the pros and cons of the use of these formulations is necessary. We evaluated the levels of resistance to 1.