|Publication Type:||Journal Article|
|Year of Publication:||1992|
|Authors:||P. W. Johnson, Boray, J. C., Dawson, K. L.|
|Journal:||Australian Veterinary Journal|
|Pagination:||213 - 217|
|Keywords:||Administration, Topical, animals, Drug Combinations, insecticide, Insecticide Resistance, Lice Infestations/drug therapy/veterinary, Mallophaga classification, Pyrethrum, Research Support, Non-U.S. Gov't, sheep, Sheep Diseases/drug therapy|
Groups of sheep infested with strains of Bovicola (Damalinia) ovis were obtained from flocks either with a history of failure to control lice with synthetic pyrethroid (SP) pour-on insecticides, or from farms where SP compounds were not used. The sheep were treated according to the manufacturer's recommendations with registered "off-shears" SP formulations. All treatments were applied under ideal conditions with doses calculated on an individual body weight basis and applied to the dorsal mid-line from the base of the neck to the butt of the tail. Treated sheep were kept in pens and maintained in separate groups. The pour-on SP treatments significantly reduced the lice population but failed to eliminate the infestation in 7 of 13 experiments in sheep carrying strains of lice with resistance factors of greater than 4 to at least one of the SP compounds. Failures occurred with all three of the SP pour-ons currently registered for lice control in NSW and with both water-based and organic solvent-based formulations.