Goat is not a scapegoat in escalating anthelmintic resistance in Small Ruminants

Abstract

Sheep and goats share the same species of gastrointestinal nematode parasites. The browsing animals (goats) suffer from parasitic gastroenteritis with comparatively lesser burden of parasitic nematodes than in sheep. Traditionally the dose rates of anthelmintics used in goats to control gastrointestinal nematodes are same as in sheep. Pharmacokinetics of anthelmintics in general, benzimidazoles and closantel in particular, reveal that goats remove anthelmintics from their body faster than sheep resulting in the reduced bioavailability of anthelmintics. Administration of anthelmintics in goats at dose rate recommended for sheep results in lower efficacy that in turn, results in the heterozygote resistant parasites being selected. The dosing of goats with the sheep dose of anthelmintics is similar in consequence to under-dosing with the effect of allowing the heterozygote resistant worms to survive. Goats are thus singularly blamed with the claim that resistance develops first in goats and then spread into the sheep flock. The ways of tackling the problem of anthelmintic resistance in goats are discussed.