The control of lice on domestic livestock.

Trials showed that existing treatments for lice on cattle were not completely effective. A few long-nosed lice, Linognathus vituli survived treatment with louse powder containing gamma HCH (BHC), amitraz spray and Prolate pour-on (20% phosmet). One treatment with cyhalothrin or cypermethrin gave complete control of all four species of lice infesting cattle in the UK. These synthetic pyrethroids were applied as sprays containing 250 p.p.m. and 1000 p.p.m. of active constituent, respectively. Another synthetic pyrethroid, deltamethrin was very effective against all species of cattle lice when applied as a spot-on: it rapidly cleared L. vituli from heavily infested animals, leaving only a small residual population in the hock joints, which eventually disappeared. Cypermethrin, when incorporated into a plastic eartag at 8.5% w/w gave a measure of louse control on cattle but was not completely effective against L. vituli and Solenopotes capillatus. Ivermectin was completely effective against L. vituli and S. capillatus and completely cleared these lice species from heavily infested animals.