title: Multispecies resistance of cattle gastrointestinal nematodes to long-acting avermectin formulations in Mato Grosso do Sul.
abstract: The use of long-acting avermectins (AVMs) in cattle to treat infections with gastrointestinal nematodes was common in Brazil until its prohibition by state authorities. The prohibition; however, was rescinded in 2015, but a scientific discussion of the pros and cons of the use of these formulations is necessary. We evaluated the levels of resistance to 1.0 and 3.5% doramectin and to 3.15% ivermectin in cattle. The worms in animals treated with 3.5% doramectin were characterized by the suppression of oviposition and by a higher proportion of adult females carrying no eggs. Haemonchus placei, Cooperia punctata, C. pectinata, C. spatulata, and Oesophagostomum radiatum were resistant to the above compositions. The administration of long-acting AVM formulations did not result in a higher efficacy against these helminth populations.
authors.affiliation: Universidade Federal de Mato Grosso do Sul, UFMS, Campo Grande, MS 79070-900, Brazil. Electronic address: fernando.borges@ufms.br.
authors.forename: Fernando de Almeida
authors.initials: Fde A
authors.lastname: Borges
authors.affiliation: Universidade Federal de Mato Grosso do Sul, UFMS, Campo Grande, MS 79070-900, Brazil.
authors.forename: Dyego Gonçalves Lino
authors.initials: DG
authors.lastname: Borges
authors.affiliation: Universidade Federal de Mato Grosso do Sul, UFMS, Campo Grande, MS 79070-900, Brazil.
authors.forename: Rafael Pereira
authors.initials: RP
authors.lastname: Heckler
authors.affiliation: Universidade Federal de Mato Grosso do Sul, UFMS, Campo Grande, MS 79070-900, Brazil.
authors.forename: Juliana Paniago Lordello
authors.initials: JP
authors.lastname: Neves
authors.affiliation: Universidade Federal de Mato Grosso do Sul, UFMS, Campo Grande, MS 79070-900, Brazil.
authors.forename: Fernando Gonçalves
authors.initials: FG
authors.lastname: Lopes
authors.affiliation: Universidade Federal de Mato Grosso do Sul, UFMS, Campo Grande, MS 79070-900, Brazil.
authors.forename: Marcel Kenzo Vilalba
authors.initials: MK
authors.lastname: Onizuka
mesh_terms: D000818:Animals; D001938:Brazil / Q000453:epidemiology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000469:parasitology*; D005767:Gastrointestinal Diseases / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D007559:Ivermectin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008297:Male; D009348:Nematoda / Q000145:classification / Q000187:drug effects*; D009349:Nematode Infections / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*
chemical_list: D007559:Ivermectin; C084101:doramectin
keywords: Cooperia; Doramectin; Haemonchus placei; Ivermectin; Necropsy