Anthelmintic resistance in nematode parasites from goats in Spain.

In a flock of cashmere goats sited in Asturias (NW, Spain) diminished efficacy was observed following treatment with netobimin and consequently a study to demonstrate the existence of anthelmintic resistance and the species of nematode involved was conducted. Results from faecal egg count reduction tests before and after treatment with netobimin or ivermectin showed efficacies of 89.4 (81.8-94.8) and 99.7% (93.9-99.9%), respectively. Teladorsagia circumcincta was found to be the dominant species involved in netobimin resistance. Effective dose (ED50) values in the egg hatch assay of 0.22 microgram thiabendazole ml-1 confirmed the existence of benzimidazole carbamate resistant nematodes. To the best of our knowledge, this is the first report on the existence of anthelmintic resistant nematodes from ruminants in Spain.