Resistance to benzimidazole and macrocyclic lactone anthelmintics in cattle nematodes in Argentina
In April 2003, persistent scouring and ill-thrift that was reported in calves form an intensive beef rearing operation in central Argentina despite treatments with benzimidazole and ivermectin. In order to conduct a controlled faecal egg count reduction test on this herd, 40 calves 5–8-months-old we...
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Published in | Veterinary parasitology Vol. 122; no. 4; pp. 303 - 306 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
Elsevier B.V
06.08.2004
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Subjects | |
Online Access | Get full text |
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Summary: | In April 2003, persistent scouring and ill-thrift that was reported in calves form an intensive beef rearing operation in central Argentina despite treatments with benzimidazole and ivermectin. In order to conduct a controlled faecal egg count reduction test on this herd, 40 calves 5–8-months-old were selected on the basis that they had a nematode eggs per gram (epg) of faeces count greater than 150. Animals were divided into four groups (1–4) of 10 calves. Calves of groups 1–3 were treated, respectively, with subcutaneous injection of ivermectin (200
mcg/kg), ricobendazole (4
mg/kg) and levamisole (7.5
mg/kg), while calves of group 4 remained as untreated controls. The egg count reductions carried out 10 days later were lower than 15% in calves treated with ivermectin and ricobendazole, but 100% in animals receiving levamisole. Pooled post-treatment faecal cultures showed larval percentages of 92 and 95 for
Haemonchus and 8 and 5 for
Cooperia in the faeces of calves treated with ivermectin and ricobendazole, respectively. This is the first reported case of
Haemonchus parasiting cattle showing simultaneous resistance to avermectins and benzimidazole type anthelmintics. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0304-4017 1873-2550 |
DOI: | 10.1016/j.vetpar.2004.05.018 |