Tapeworms are usually caused by ingesting a flea and is easily treated with a pill.
Treating all the pets in the house for fleas is essential to prevent reinfection of the worm.
The tapeworm is harmless save for some anal itchiness.
Sounds like Tape worm. Unless there are other meds out there now I don 't know about, usually a dose of Droncit takes care of it. All pets should be treated. If fleas are a problem, wash the animals, bedding, vacuum well (throw away the bag), etc.
Google "Tape Worm" for the answers to your questions......Tape Worm segments look like rice after they have dried out......Usually, other dogs in the household need to be treated, also. Good luck..........