Abstract: This invention provides topical ectoparasiticidal fomulations comprising an ectoparasiticide, preferably a pyrethroid or a spinosyn, a spreading agent at is a (C3-C6) branched alkyl (C10-C20) alkanoate, preferably isopropyl myristate, and optionally a miscibilizing agent compatible with organic solvent systems, and methods of controlling an ectoparasite infestation on certain animals comprising topically applying such formulations to the animal.

Abstract: The invention provides a stable ectoparasiticidal aqueous suspension formulation of a spinosyn, comprising the spinosyn, or a physiologically acceptable derivative or salt thereof, milled to an average particle size of 1 to 15 microns, a surfactant in an amount effective to facilitate wetting the milled particles; a dispersant in an amount that forms a spinosyn;dispersant weight ration of from 3:1 to 1:5; and water. It also provides a method of controlling an ectoparasite infestation on a small ruminant or companion animal comprising administering an effective amount of such an aqueous suspension formulation.