Abstract

Critical controlled tests were performed in 157 sheep (8 experiments) and 34 cattle (2 experiments) to evaluate the anthelmintic activity of mebendazole suspension, administered intraruminally via a stomach tube at a dosage rate of 15 mg of mebendazole/kg of body weight, against induced infections of immature and adult stages of commonly encountered nematode parasites in South Africa. In the sheep, the controlled efficacy of mebendazole suspension was good to excellent (90.1% to 100%) against all stages of Haemonchus contortus, Trichostrongylus colubriformis, Gaigeria pachyscelis, Ostertagia circumcincta, Nematodirus spathiger, and Chabertia ovina species. Mebendazole was also highly effective (97.3% to 99.9%) against 4th, 5th, and adult stages of Oesophagostomum columbianum and 5th-stage and adult Dictyocaulus filaria. Moderate activity was obtained (79.8% to 82.2%) against 3rd-stage O columbianum, 3rd- and 4th-stage D filaria, and 5th-stage and adult Strongyloides papillosus. In the cattle, mebendazole was effective (91.5% to 100%) against 4th-stage and adult H placei, Cooperia pectinata, Bunostomum phlebotomum, and Oesophagostomum radiatum species, but did not exhibit any appreciable activity (27.3% to 41.5%) against 4th-stage and adult O ostertagi.