The adult D. caninum tapeworm lives in an animal's small intestine. As the worm continually grows, individual body segments, each full of eggs, pass in the animal's feces. As the segments dry, they break open and release the eggs. Flea larvae ingest the eggs, which then grow into immature worms inside the fleas. When your pet ingests a flea (usually while grooming), the flea releases the tapeworm, which then grows into an adult in your pet's intestine, completing the life cycle.
The D. caninum tapeworm cannot pass directly from cat to cat or dog to dog. Further, an animal cannot become infected simply by eating tapeworm eggs.
To prevent this detrimental life cycle, treat your affected pet with a wormer that kills tapeworms, and use a flea and tick preventive. A non-prescription wormer medication such as WormXPlus (for dogs only) or TapeWorm Tabs® for Dogs or Cats will kill the tapeworms. Use the wormer along with a proven flea and tick preventive such as Frontline® Plus. Continue with the flea and tick preventive even after tapeworms are gone to minimize your pet's risk of becoming re-infected with tapeworms.