title: Effectiveness of doramectin for treatment of experimentally induced gastrointestinal tract larval nematode infections in calves.
abstract: Anthelmintic efficacy of doramectin, a macrocyclic lactone of the avermectin family, was evaluated against larval parasitic nematodes in calves. The investigational product was given SC at a dosage of 0.2 mg/kg of body weight to 10 calves infected 6 days previously with third-stage larvae of the genera Haemonchus, Ostertagia, Cooperia, and Nematodirus. Ten additional calves with identical larval exposure were given saline solution SC also at 6 days after inoculation, and served as the nonmedicated controls. At 14 or 15 days after treatment, the calves were slaughtered in complete replicate for nematode recovery and subsequent quantifications. In comparing nematode numbers at necropsy for the saline- and doramectin-treated groups, nematocidal effectiveness as directed against fourth-stage larvae was: 100% for Haemonchus placei and Cooperia spp, > 99% for Ostertagia ostertagi, and 64.5% for Nematodirus helvetianus. All treatments were easily administered, and adverse behavioral or tissue reactions were not seen to result from doramectin administration.
authors.affiliation: Department of Animal Science, University of Arkansas, Fayetteville 72701.
authors.forename: T A
authors.initials: TA
authors.lastname: Yazwinski
authors.forename: H
authors.initials: H
authors.lastname: Featherston
authors.forename: C
authors.initials: C
authors.lastname: Tucker
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000469:parasitology; D005243:Feces / Q000469:parasitology; D005260:Female; D005767:Gastrointestinal Diseases / Q000188:drug therapy / Q000469:parasitology / Q000662:veterinary*; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D007814:Larva / Q000187:drug effects; D008297:Male; D009349:Nematode Infections / Q000188:drug therapy / Q000469:parasitology / Q000662:veterinary*
chemical_list: D000871:Anthelmintics; D007559:Ivermectin; C084101:doramectin