COMPARATIVE EFFICACY OF MOXIDECTIN AND MEBENDAZOLE AGAINST GASTROINTESTINAL NEMATODES IN EXPERIMENTALLY INFECTED LAMBS

A controlled trial was conducted to determine the anthelmintic efficac ies of moxidectin and mebendazole. The compounds were administered ora lly at doses of 0.2 mg/kg bodyweight and 15.0 mg/kg bodyweight, respec tively, to lambs infected experimentally with large numbers of gastroi ntestinal nematode larvae including a benzimidazole-resistant strain o f Haemonchus contortus. Moxidectin was 100 per cent effective against adult H contortus, Ostertagia species, Trichostrongylus colubriformis, Cooperia curticei and fifth stage larvae of Oesophagostomum species a nd Chabertia ovina, but was only 76 per cent effective against adult S trongyloides papillosus. Mebendazole was 100 per cent effective agains t adult Ostertagia species and T colubriformis, but reduced the number s of adult C curticei by only 39 per cent, S papillosus by 58 per cent , H contortus by 76 per cent, and fifth stage larvae of Oesophagostomu m species by 79 per cent and C ovina by 72 per cent.