Effectiveness of strategic anthelmintic dosing in controlling Haemonchus contortus infections in sheep in the United Kingdom
Taylor, M.A.; Hunt, K.R.; Wilson, C.A.; Quick, J.M.
Veterinary Record 129(9): 189-192
1991
ISSN/ISBN: 0042-4900 PMID: 1957469 Document Number: 378737
The strategic use of anthelmintics in the control of infections of Haemonchus contortus in ewes and lambs, was investigated in a series of paddock trials. The levels of infection and clinical signs associated with the presence of either benzimidazole-resistant or benzimidazole-susceptible strains of H. contortus in lambs were controlled by regular drenching with levamisole or mebendazole, respectively, or by the strategic use of closantel in combination with mebendazole. In the latter case, control was achieved by dosing either the ewes in the early part of the grazing season, or the lambs from June onwards. It was concluded that worm control strategies based on clasantel could provide effective control of both benzimidazole-susceptible and bezimidazole-resistant strains of H. contortus on farms in the United Kingdom.