Product Description WSD CLOSANTEL is a narrow spectrum treatment for internal parasites of sheep and lambs with sustained action against re-infestation by Haemonchus contortus (barbers pole worm), and activity against Fasciola hepatica (liver fluke). Type of Preparation WSD CLOSANTEL is a clear solution for oral use as a drench containing 37.5g/L closantel – a member of the salicylanilide and substituted phenol group of compounds.