In a session at the 2026 Fetch National Harbor conference, Nathanael Oster, VMD, MBA, walked attendees through the biology, diagnosis, and treatment of the flea tapeworm in dogs and cats, including why cats are affected more often than dogs.
At the 2026 Fetch National Harbor Veterinary Conference, Nathanael Oster, VMD, MBA, presented the lecture "Tapeworms in Dogs and Cats," covering multiple species that can affect pets. This article focuses on his discussion on the flea tapeworm, Dipylidium caninum. A point Oster returned to was that, in his words, "flea control is a good tapeworm control."
The dog or cat is the definitive host, and the flea is the intermediate host, Oster explained. The adult tapeworm sheds egg-filled segments, called proglottids, that pass in the stool. Flea larvae—ones wiggling around in carpet, cracks in wood boards, or outside—ingest those eggs, and the flea carries the infective stage by the time it reaches adulthood. When a dog or, as Oster said is more likely, a cat grooms and swallows the flea, it picks up the adult tapeworm. Oster noted a pet can also become infected by eating another animal, such as a mouse, that is carrying fleas.
Clinical signs are usually minimal. "Generally, this is not something that we see clinical signs with," Oster said, adding that most often the proglottids are found and the pet is treated. Less commonly, he said, there can be gastrointestinal signs or irritation in the perianal region.
The flea tapeworm is rarely zoonotic, according to Oster. Children can become infected, but infection occurs from ingesting the infected fleas, rather than from being around a pet that is shedding proglottids. Still, although the parasite is rarely zoonotic, visible proglottids can affect the human-animal bond, because owners who recognize them may become reluctant to pet the animal or keep it indoors.
One point Oster raised was the difference between cats and dogs when it comes to flea tapeworms. According to Oster, Dipylidium rates in cats run about four times higher than in dogs. Three possible reasons for this, Oster explained, are that cats receive fewer tapeworm treatments, cats are kept on monthly flea prevention less consistently, and, through grooming, cats can eat the fleas faster than dogs generally do.
Because owners can see tapeworm proglottids, unlike the microscopic ova of roundworms and hookworms, Oster described using the visible segments to help reinforce client compliance.
Diagnosis is usually a matter of the tapeworm simply being found, Oster said. Fecal flotation is an option, but he said it is not very good for these tapeworms. Fecal PCR is also available, as is antigen testing, which Oster said can help identify which species is involved and detect it earlier, since antigen tests can pick it up sooner than other methods.
For treatment, Oster said praziquantel can be given in a variety of ways, including single doses and monthly products. Epsiprantel is another available option, he said. He also noted a combination product for cats that includes a monthly praziquantel dose, which he said can be used as a dewormer or for continuous treatment and control.
Oster also addressed global praziquantel resistance in the flea tapeworm. He said the first case was reported in Switzerland, followed by cases in the US across several states that appeared to be associated with one litter of dogs. He emphasized the importance of being aware of resistance while noting that it has not been reported in cats to date. He said that may be because cats generally receive fewer drugs than dogs.
“Like with some other things [and] resistance, it's good to be aware of it. But this is not something that's running rampant or running wild,” Oster said.
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