Published online by Cambridge University Press: 10 February 2020
Our objective was to measure the efficacy of ivermectin (IVM) and benzimidazoles (BZ, i.e. fenbendazole and albendazole) in 15 cattle farms in western France and southern Italy. A total of 11 groups were treated with IVM and 11 with BZ. Efficacy was assessed by calculating the percentage of faecal egg count reduction (%FECR) using the pre- and post-treatment arithmetic means. Anthelmintic resistance was considered to be present when the %FECR was <95% and the lower limit of the 95% confidence interval <90%. For IVM, the percentages of FECR ranged from 73% to 100%. Lack of efficacy to IVM was detected in two farms out of four in France, but was not detected in any of the seven farms in Italy. For BZ, the percentages of FECR ranged from 95% to 100%. No case of BZ resistance was detected in the five farms in France and the six farms in Italy.