The anthelmintic efficacy of thiabendazole and levamisole against inhibited Haemonchus contortus larvae in sheep

Abstract

Extract

Inhibition in the parasitic development of trichostrongylid nematodes is a commonly reported phenomenon (Michel, 1968) and its occurrence in Ostertagia ostertagi infections in cattle particularly well documented (Martin et al., 1957; Michel, 1963; Anderson et al., 1965; Armour et al., 1969a, b; Brunsdon, 1973). In this parasite inhibition occurs at the early fourth larval stage and of primary veterinary importance, in the fact that, in contrast to normally developing larvae, such inhibited forms are insusceptible to all known anthelmintics (Armolur, 1970).