Especially round and flat worms (such as roundworms, tapeworms, hookworms etc.) belong to internal parasites attacking the intestinal system of animals. Unfortunately, a risk of transferring the contamination on a human exists here. Therefore it is necessary to decant the animals regularly and to remove their excrements from the environment. The tablets with the anti-parasite effect are administered perorally or in food or crashed in food. The dose is determined with respect to the animal weight.