Annette, dogs can also get tapeworms by ingesting another animal that has them (rodents and rabbits commonly have them), or even by ingesting a carrier's feces . Feral/roaming cats are big carriers of both fleas and tapeworms, and we all know how much dogs like cat leavings. Parasites are one of the few creatures in the animal kingdom that actually truly disgust and repulse me
Jessica, we do have cats, squirrels, and bunnies come in our fence frequently, that's how I suspect she may have got them!