MOXIDECTIN AGAINST IVERMECTIN-RESISTANT NEMATODES - A GLOBAL VIEW

Macrocyclic lactone endectocides include two chemically distinct compo unds moxidectin, a milbemycin, and ivermectin, an avermectin. The sign ificance of the chemical differences between these compounds in relati on to nematode resistance remains to be established. Reported studies indicate that moxidectin at the recommended dose rate of 0.2 mg/kg con trols identified strains of nematodes, isolated from sheep and goats, with demonstrated resistance to ivermectin. This reflects the signific antly greater potency of moxidectin against the 3 genera of nematodes most commonly involved in anthelmintic resistance, Haemonchus, Osterta gia and Trichostrongylus. Moxidectin, in recommended strategic treatme nt programmes, should reduce the risk of further development of resist ance to the macrocylic lactone endectocides.