| Abstrakt: |
The ellicacy of two recently introduced benzimidazole anthelmintics, albendazole and fenbendazole, was determined for six-day, 10-day and adult stages of resistant strains of Haemonehus contortitsand Trichostrongylus colubriformis. Albendazole, at 3·8 mg/kg reduced H contortitsworm counts by 92·4, 70·8 and 67·1 per cent while fenbendazole, at 5·0 mg/kg, reduced worm burdens by 51·7, 95·5 and 93·4 per cent against six-, 10- and 25-day-old parasites respectively. For T colubriformis, the corresponding reductions with albendazole were 97·7, 95·8 and 64·9 per cent and for fenbendazole 29·0, 66·3 and 33·4 per cent. Compared with susceptible strains of H contortitsand T colubriformis, for which therapeutic doses of benzimidazole anthelmintics are generally highly active against all stages of development, the present results show that these drugs do not have a uniform level of activity against all developmental stages of resistant strains. |
