Tapeworms are a type of parasite, also known as a cestode, which lives in the intestines of infected mammals. Dogs may become infected with tapeworms if they eat animal meat that is contaminated with the worms, but in most cases they become infected with tapeworms by ingesting fleas that are carrying tapeworm eggs. Tapeworms are named so because of their long, flattened, shape which looks similar to a piece of tape.
Medications which contain praziquantel are the only medications that will successfully treat tapeworms. Many dog owners make the mistake of buying over the counter de-worming medication to treat tapeworms. However most of these medications will only treat roundworms or hookworms.