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Research article - Peer-reviewed, 2013

Limited efficacy of pour-on anthelmintic treatment of cattle under Swedish field conditions

Areskog, Marlene; Ljungström, Bitte; Höglund, Johan


A study on the effect of topical macrocyclic lactones (ML) against gastrointestinal nematodes (GIN) in Swedish first season grazing cattle (FSG) was performed during the grazing seasons of 2009 and 2010. Herds were recruited through farming press and both dairy and beef cattle farms were invited. A questionnaire revealed that 64% of participating farmers dewormed their animals in previous years, and of these 76% used topical formulations with ML. Four to six weeks after turnout, 107 (2009) and 64 (2010) farmers sent in individual faecal samples from 6-10 FSG. Faecal egg counts (FEC) were determined by the FECPAK (R)-method in 2009 and the McMaster-method in 2010, when also larvae were cultured. Average FEC of >= 100 eggs per gram faeces (EPG) was seen in 39% of the herds in 2009 and 42% in 2010 and with arithmetic means of 258 +/- 110 and 252 +/- 350 EPG, respectively. Interestingly, FSG in dairy and beef herds had similar mean FEC. In herds with mean FEC of >= 100 EPG, farmers dewormed all FSG in the tested grazing group with ivermectin (IVM) or doramectin (DOR) pour-on. In 2009, 33 (31%), and in 2010, 26 (40%) of the herds were retested 7-16 days post treatment. Mean reduction was 89% and 88%, respectively, and in only 12 (36%) and 10 (38%) herds it was >= 95%. Beef herds had mean reductions similar to those of the dairy herds. No significant difference (P = 0.66) in reduction was seen between the groups treated with three different pour-on formulations, nor was there any correlation between the previous year's usage of anthelmintics and the efficacy. Larvae from post-treatment cultures analysed in 2010 with a species-specific ITS2 qPCR showed that Cooperia oncophora was the predominant species after deworming. Four (15%) groups also harboured surviving Ostertagia ostertagi post treatment. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.


Gastrointestinal parasites; Doramectin; Ivermectin; Anthelmintic resistance

Published in

International Journal for Parasitology: Drugs and Drug Resistance
2013, volume: 3, pages: 129-134

Authors' information

Areskog, Marlene
Swedish University of Agricultural Sciences, Department of Biomedical Science and Veterinary Public Health
Ljungström, Bitte

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