THE PERSISTENCE OF THE EFFICACY OF INJECTABLE OR ORAL MOXIDECTIN AGAINST TELADORSAGIA, HAEMONCHUS AND TRICHOSTRONGYLUS SPECIES IN EXPERIMENTALLY INFECTED SHEEP

The persistence of the efficacy of moxidectin was evaluated against ex perimental gastrointestinal nematode infections in 55 lambs randomly a llocated to 11 equal groups and infected on day 0, Moxidectin 1 per ce nt injectable solution was administered at a dose rate of 0.2 mg moxid ectin/kg bodyweight to five of the groups on days -42, -35, -28, -21 a nd -14; five other groups were treated with moxidectin 0 1 per cent or al drench at the same dose rate on days -35, -28, -21, -14 and -7, and the 11th group remained untreated as a control, The lambs were infect ed experimentally with 8000 Teladorsagia circumcincta, 2000 Haemonchus contortus and 10,000 Trichostrongylus colubriformis infective larvae and killed three weeks later, Both formulations of moxidectin showed e xcellent activity against T circumcincta and H contortus with almost 1 00 per cent efficacy against the abomasal parasites for up to 35 days after treatment, The efficacy of moxidectin 1 per cent injectable agai nst T colubriformis was much higher (>99 per cent) than that of the or al drench and it was highly effective up to 21 days after treatment, a nd gave a moderate reduction in worm burden for up to 35 days after tr eatment, No adverse reactions to moxidectin were observed in any of th e animals.