title: Persistent anthelmintic activity of ivermectin in cattle.
abstract: Two studies are described which demonstrate the persistent activity of ivermectin injected subcutaneously into cattle at 200 micrograms/kg in preventing the establishment of induced infections with the gastrointestinal parasites Ostertagia ostertagi and Cooperia oncophora and the lungworm Dictyocaulus viviparus. These results indicated a reduction in mean worm count compared with the control group for O ostertagi of more than 99, 45 and 94 per cent with a seven, 14 or 21 day interval between treatment with ivermectin and the administration of infective larvae, respectively, in trial 1 and more than 99, more than 99 and 99 per cent at seven, 10 or 14 days, respectively, in trial 2. Corresponding values against C oncophora were 99, 0 and 45 per cent at seven, 14 and 21 days in trial 1 and more than 99, 84 and 31 per cent at seven, 10 and 14 days in trial 2. Against D viviparus, reduction in counts were more than 99, 98 and more than 99 per cent at seven, 14 and 21 days, respectively, in trial 1 and 100, 100 and 100 per cent at seven, 10 and 14 days, respectively, in trial 2. The relevance of these results to the build-up of infective larvae on pasture and infection in cattle is discussed.
authors.forename: J
authors.initials: J
authors.lastname: Armour
authors.forename: K
authors.initials: K
authors.lastname: Bairden
authors.forename: A F
authors.initials: AF
authors.lastname: Batty
authors.forename: C C
authors.initials: CC
authors.lastname: Davison
authors.forename: D B
authors.initials: DB
authors.lastname: Ross
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D000969:Antinematodal Agents / Q000627:therapeutic use; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000469:parasitology; D004022:Dictyocaulus Infections / Q000188:drug therapy*; D005260:Female; D007559:Ivermectin; D007783:Lactones / Q000494:pharmacology*; D008297:Male; D009348:Nematoda / Q000187:drug effects; D009349:Nematode Infections / Q000188:drug therapy / Q000662:veterinary*; D010029:Ostertagiasis / Q000188:drug therapy / Q000662:veterinary*; D014252:Trichostrongyloidiasis / Q000662:veterinary*
chemical_list: D000871:Anthelmintics; D000969:Antinematodal Agents; D007783:Lactones; D007559:Ivermectin