title: Control of helminthosis in lambs by strategic treatment with closantel and broad-spectrum anthelmintics.
abstract: Treatment of ewes with broad-spectrum anthelmintic in August (pre-lambing) and early November, and of lambs in early November and early February, was effective in controlling infections with Trichostrongylus spp in lambs reared on contaminated pastures under set-stocked conditions. It was ineffective in controlling infections with Haemonchus contortus; 82% of lambs had to be withdrawn from the experiment because of severe haemonchosis. Treatment with closantel (7.5 mg/kg) at the same times was very effective against H. contortus but ineffective against Trichostrongylus spp; 25% of lambs had to be withdrawn because of severe trichostrongylosis. The same schedule using broad spectrum anthelmintic and closantel administered concurrently was effective against both parasites; no lambs had to be withdrawn and the bodyweight gain of lambs was higher than in lambs treated with broad-spectrum anthelmintic or closantel alone. The results provide a basis on which to develop a preventive anthelmintic treatment program to control haemonchosis and trichostrongylosis in sheep which will allow the current high frequency of treatment with broad-spectrum anthelmintics to be reduced. Such a program may retard selection for anthelmintic resistance in Trichostrongylus spp.
mesh_terms: D000818:Animals; D001562:Benzimidazoles / Q000008:administration & dosage* / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005243:Feces / Q000469:parasitology; D005260:Female; D006188:Haemonchiasis / Q000188:drug therapy / Q000469:parasitology / Q000517:prevention & control / Q000662:veterinary; D007978:Levamisole / Q000008:administration & dosage* / Q000627:therapeutic use; D008685:Meteorological Concepts; D010029:Ostertagiasis / Q000188:drug therapy / Q000469:parasitology / Q000517:prevention & control / Q000662:veterinary; D010270:Parasite Egg Count; D011247:Pregnancy; D012457:Salicylamides / Q000008:administration & dosage*; D012458:Salicylanilides / Q000008:administration & dosage* / Q000627:therapeutic use; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy* / Q000469:parasitology / Q000517:prevention & control; D014252:Trichostrongyloidiasis / Q000188:drug therapy / Q000469:parasitology / Q000517:prevention & control / Q000662:veterinary*
chemical_list: D001562:Benzimidazoles; D012457:Salicylamides; D012458:Salicylanilides; D007978:Levamisole; C023342:closantel; C011030:oxfendazole