Simultaneous resistance to two or more broad-spectrum anthelmintics by gastrointestinal nematode parasites of sheep and goats.

The detection, by means of faecal egg count reduction tests and larval cultures, of two cases of multiple anthelmintic resistance in goats and two in sheep, is reported. The former cases appeared to involve resistance to all three broad-spectrum drench groups (benzimidazole, levamisole, ivermectin) by mainly Ostertagia spp., the latter resistance to two of them (benzimidazole, levamisole) by Trichostrongylus spp.