Yes they can contact tapeworms by ingesting a flea, also by a rodent & they can also get them from eating other dogs feces. (even if your god does not eat feces it can step in a nother dogs pile & lick his feet). Even though your dog does not have fleas it just needs to eat one (you might not of seen that one little flea LOL). It can not be transfered from pet to pet, it has to be ingested.