Abstract
The gastrointestinal nematode of sheep, Haemonchus contortus has been resistant to several active principles, among them Ivermectin, anthelmintic with antihelminthic resistance, but widely used for the treatment and control of gastrointestinal nematodes in sheep. Some mechanisms of resistance to ivermectin have been elucidated and the participation of the P-glycoprotein is listed as the m…