Nothing on that page says that pyrantels are effective against lice. It says on the chart that the drugs denoted by the d
are effective against lice and the only group marked with that d
is the avermectinswhich are ivermectin and moxidectin.
Sorry, but I do remember my pharmacology and parasitology lessons. Pyrantel is not effective against lice. "Pediculosis (Lice) Lice are wingless, flattened insects that are ectoparasites of mammals worldwide. They constitute two orders: Anoplura (sucking lice, blood feeders) and Mallophaga (biting lice). Two species of lice affect horses: Damalina equi a biting louse that feeds on skin and hair, and Haematopinus asini a sucking louse that pierces skin and sucks blood and tissue fluids. Infestations are common. The life cycle is completed on the host and transmission is mainly by direct contact. Infections are more severe in the late winter and early spring. The skin irritation results in itching manifested by rubbing, biting and kicking. The coat may be roughened with loss of hair and there may be secondary bacterial infection. In heavy infestations individuals become anemic and lose weight and condition. Diagnosis This is based upon finding eggs or lice. The latter are 2 - 4 mm in size and thus can be readily seen when hair is parted. Biting lice are more active than sucking lice. Treatment Dipping or spraying with insecticide solutions; two treatments two weeks apart are recommended. Ivermectin is effective against sucking lice but not biting lice. Frequent and thorough grooming is helpful in controlling pediculosis." --A Concise Guide to the Microbial and Parasitic Diseases of Horses, Carter G.R., Payne P.A. And Davis E. (Eds.). http://www.thehorse.com/ViewArticle.aspx?ID=5469