Efficacy of three broad-spectrum anthelmintics against gastrointestinal nematode infections of goats

Abstract Groups of 10 goats, harbouring both naturally acquired and experimental infections of gastrointestinal nematodes, were drenched with either levamisole (5 mg kg −1 ), albendazole (3.8 mg kg −1 ) or parbendazole (15 mg kg −1 ), or remained untreated. Haemonchus contortus was the numerically dominant infection, with Strongyloides papillosus, Trichostrongylus colubriformis and Oesophagostomum columbianum also present. At 5–6 days post-treatment, goats were killed and necropsied. Post-mortem worm counts showed that the reduction in mean total worm burdens was 57.4% in levamisole-treated animals, 71.1% in the albendazole group and 85.1% in the parbendazole group. Reductions for H. contortus were 80.2, 87.9 and 83.9% in the levimisole-, albendazole- and parbendazole-treated groups, respectively. These data indicate that the anthelmintics in question are not being applied at an adequate dose rate for goats, and/or resistance to anthelmintics is occurring in the field in Pernambuco State, northeast Brazil.