COMPARATIVE EFFICACY OF FENTHION, DICHLORVOS FENITROTHION AND PERMETHRIN AGAINST THE FLEA, CTENOCEPHALIDES-FELIS, ON THE DOG

In a series of three replicated and controlled trials, nine dogs artif icially infected with Ctenocephalides felis were treated with a system ically active 'spot-on' formulation of fenthion, six with a topical sp ray containing dichlorvos and fenitrothion and six with a surface acti ve 'spot-on' preparation containing permethrin, all at recommended dos e rates. Good knockdown efficacy was apparent at eight hours with the dichlorvos/fenitrothion combination and at 24 hours with the other for mulations. Efficacy values in excess of 95 per cent persisted for at l east 22 days in the case of the systemic fenthion preparation and the permethrin product and eight days for the dichlorvos and fenitrothion combination. Twenty-nine days after treatment there was still substant ial protection in the fenthion- and permethrin-treated animals, indica ted by an 88 and a 77 per cent reduction in flea counts in the two gro ups, respectively.