A small scale survey of ivermectin resistance in sheep nematodes using the faecal egg count reduction test on samples
D J Bartley1, A A Donnan, E Jackson
1Department of Parasitology, Moredun Research Institute, Pentland Science Park, Bush Loan, Penicuik EH26 0PZ, UK. dave.bartley@moredun.ac.uk
Abstract:
Thirty-eight sheep flocks, predominantly from the south/central Scotland, were examined using a faecal egg count reduction test (FECRT) for the presence of ivermectin (IVM) resistant nematodes. Efficacies of less than 95%, 14-17 days post-treatment, were identified in 6 of 17 naturally grazing flocks where pre-treatment faecal egg counts were in excess of 150 eggs per gram. Efficacies on these IVM resistant farms ranged from 66 to 92%. One other suspected cases of IVM resistance was also identified in returned material. The larvae detected in post-treatment coprocultures from resistant flocks were from the genera Teladorsagia (4 from 6) and Trichostrongylus (2 from 6).
