An evaluation of two cypermethrin-based pour-on formulations on sheep infected with the biting louse, Bovicola ovis

Authors: Bishop DM, Cole DJW, Nottingham RM, Heath ACG
Publication: New Zealand Veterinary Journal, Volume 40, Issue 3, pp 104-106, Sep 1992
Publisher: Taylor and Francis

Animal type: Livestock, Production animal, Ruminant, Sheep
Subject Terms: Animal remedies/veterinary medicines, Inflammation, Integument/skin/wool/hair/fur/feather, Disease/defect, Treatment/therapy, Pest/pesticides, Agricultural compounds, Parasites - external, Parasites - internal
Article class: Scientific Article

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Abstract: Two synthetic pyrethroid (cypermethrin) based “pour-on” insecticide formulations, with high cis/trans isomer ratios (80:20) but differing in their respective active ingredient concentrations and solvent component(s), were applied to sheep infested with the biting-louse, Bovicola ovis. All treated sheep were penned with louse-infested sheep 9,12 and 15 weeks after the insecticide was applied. The 2% cypermethrin formulation achieved a higher level of control than the 1.25% cypermethrin formulation at each challenge interval when applied 12 weeks after shearing. The 2% cypermethrin formulation provided 97-100% control of lice from 4 to 16 weeks after application on sheep shorn 6 or 12 weeks prior to treatment. The 1.25% cypermethrin formulation provided 85% control of lice 4 weeks after application on sheep shorn 12 weeks prior to treatment, the level of control increasing to a maximum of 100% by week 9, and declining thereafter. The 2% cypermethrin formulation may provide a better level of control in long-woolled sheep than 1.25% cypermethrin, by compensating for the diluent effect of lipid.

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