zero worm bolus is a cylindrical, solid medication, which is administered orally. Roundworms, tapeworms, and flukes are just a few of the worms it is effective against when used as a dewormer. It is used to treat gastrointestinal nematode, lungworm, and tapeworm infection in cattle, sheep, and goats. This medicine can be used to treat a variety of internal and exterior parasite species as an anthelmintic ("Dewormer"). Zero worm bolus is an internal parasite medication that can be used to treat lungworms in cattle and pigs as well as gastrointestinal worms (mainly roundworms) in horses, cattle, pigs, sheep, and goats.