the chocolate does not produce parasites
The chocolate cannot produce parasites in the dogs unless the chocolate contains the infestante larva and, that is impossible!
The animals can only become infested with parasites if they ingest the immature form of the worms. One thinks that this myth comes because, the dog when eating chocolate, can have vomits and diarrea eliminating parasitic in its fecal matter and that was related whereupon, when ingesting chocolate formed the parasites.
Translation and adaptation: MV Enrique L. Fernandez De Vanna