title: Therapeutic and persistent efficacy of spinosad applied as a pour-on or a topical spray against natural infestations of chewing and sucking lice on cattle.
abstract: Studies were conducted in Wisconsin and Illinois, USA, to assess and compare the therapeutic and persistent efficacy of spinosad when applied as either a pour-on or topical spray and compared with cyfluthrin pour-on and coumaphos topical spray for controlling natural infestations of chewing (Bovicola bovis) and sucking (Linognathus vituli, Solenopotes capillatus and Haematopinus eurysternus) lice on cattle. Thirty-five animals at each trial site were blocked according to pre-treatment lice counts and randomly allocated to one of five treatment groups: single treatments of spinosad (25 g/L), diluted with water to 0.04% active ingredient and applied as a whole-body topical spray; spinosad (25 g/L) applied as a neat pour-on at 2 mg/kg body weight; Co-Ral Emulsifiable Livestock Insecticide (5.8% coumaphos), diluted to 0.03% active ingredient and applied as a whole-body topical spray; CyLence Pour-on Insecticide (1% cyfluthrin), applied as a neat pour-on at the manufacturer's recommended use rate for lice; and untreated control. Both spinosad treatments and cyfluthrin provided > or =96% control of B. bovis for up to 7 weeks, whereas the efficacy of coumaphos dropped to <90% after week 5 at one site. Spinosad spray had the best therapeutic and residual control of all treatments against L. vituli, > or =98% for at least 5 weeks at both sites, compared with 3 weeks for coumaphos at one site. Spinosad and coumaphos sprays provided 100% control of S. capillatus for at least 8 weeks compared with > or =97% control for spinosad and cyfluthrin pour-on treatments over the same interval. While H. eurysternus burden was low and limited to one study site, all four treatments provided 100% control for at least 6 weeks. These studies showed that topically applied spinosad provided a high degree of therapeutic and residual control against both sucking and chewing lice.
authors.affiliation: Elanco Animal Health Research and Development, Division of Eli Lilly & Company, Greenfield, IN, United States.
authors.forename: W Hunter
authors.initials: WH
authors.lastname: White
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Hutchens
authors.forename: Carl
authors.initials: C
authors.lastname: Jones
authors.forename: Larry D
authors.initials: LD
authors.lastname: Firkins
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Paul
authors.forename: Larry L
authors.initials: LL
authors.lastname: Smith
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Snyder
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000854:Anoplura / Q000187:drug effects* / Q000254:growth & development; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000517:prevention & control; D003372:Coumaphos / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D005260:Female; D007306:Insecticides / Q000627:therapeutic use*; D010373:Lice Infestations / Q000188:drug therapy / Q000517:prevention & control / Q000662:veterinary*; D018942:Macrolides / Q000627:therapeutic use*; D008297:Male; D009570:Nitriles / Q000627:therapeutic use; D008003:Phthiraptera / Q000187:drug effects* / Q000254:growth & development; D011722:Pyrethrins / Q000627:therapeutic use; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D004338:Drug Combinations; D007306:Insecticides; D018942:Macrolides; D009570:Nitriles; D011722:Pyrethrins; D003372:Coumaphos; C052570:cyfluthrin; C415329:spinosad