Ivermectin, an antiparasitic drug that is widely used in young goats, was avalied as to its effect on gastrointestinal nematodes, at all parasitic stages. Twelve naturally infected young goats was studied: six of them received 200µg.kg-1 of ivermectin orally, while the other six was used as controls. The faecal egg count reduction (FECR) test, the larval culture and the worm burden was estimated. Faecal samples was collected from the goats on the day of medication (day zero), at seven and at fourteen days. All the goats were killed fourteen days after treatment; helminths were collected and the total parasite load was estimated. FECR and the efficiency of the drug on adult nematodes was 42.10% and 32.62%, respectively. The genus Haemonchus represented 100% of the population in the treated group and 99.58% of the control group. These results show that the goats had already been infected by ivermectin-resistant Haemonchus strains.
ivermectin; goats; resistance
