Some flatworms burrow through a host's skin, but tapeworms, the most familiar subspecies, are ingested through intermediate hosts like fleas. Certain types migrate first to the lungs, but all end up in the intestinal tract to reproduce so their eggs can pass via stool to the environment, where they'll hatch and seek hosts. If your dog is infected, you may notice itching, vomiting, diarrhea with or without blood, worm segments in the stool, weight loss, anemia or other symptoms.
See your vet if you suspect your dog has flatworms. The nonspecific symptoms can indicate other parasitic infections, other types of infections, and many other diseases and disorders. Tell your vet all about your pet's symptoms -- and mention whether your dog has been swimming, as swimming is the most common source of water-borne flatworm infections. A stool sample is the vet's main diagnostic tool, but your vet may run blood tests or other examinations to exclude other causes of your dog's symptoms.
Wormers, medications that kill internal parasites, are the primary treatment for tapeworms and other flatworms. Oral or injected praziquantel is the most commonly used drug. It interferes with an intestinal parasite's ability to remain in place without being digested by your dog. Tapeworms are typically treated on an outpatient basis, but if your dog has other types of flatworms, ones that have laid eggs that migrated to the liver or kidneys or caused other potentially serious complications, hospitalization may be necessary until completion of treatment and convalescence.