Fenbendazole is effective for treatment of numerous helminth intestinal parasites in animals, including Toxacara, Toxascaris, Ancylostoma, and Trichuris. In dogs, it is effective for most intestinal helminth parasites and also against nematodes. In dogs, it also has been used for pulmonary helminths (lungworms), but longer duration of treatment is needed. Fenbendazole has been effective for treatment of Giardia, but higher doses are needed and there may be failure rates as high as 50%. It is effective in cats for treatment of lungworms, flukes, and a variety of helminth parasites.