Last Updated: 02/09/2025

Tapeworms in Dogs

Think your 'all-in-one' preventative covers everything? Many don't include protection against tapeworm, a common silent parasite. This expert guide details the symptoms, the tapeworm lifecycle, and the specific treatments needed to protect your dog and prevent human infection.

Author: Dr Brittany Ward BVSc

Reading Time: 11 minutes - short read

While most intestinal worms can be contracted directly from eating eggs or larvae, tapeworms have an intermediate host, also called a paratenic host. This means that part of their life cycle exists within another species before infecting your dog. In order for your dog to become infected with tapeworm, they must eat the paratenic host.

A dog that is infected with adult tapeworms will shed proglottids (segments), containing tapeworm eggs, in their faeces. The proglottids will break open and release the eggs in the faeces where they can be ingested by the paratenic host and enter the larval phase of the tapeworm life cycle.

The Flea Tapeworm (Dipylidium Caninum) uses fleas as its intermediate host. Flea larvae consume the released eggs from faeces and the larval stage of the tapeworm and flea will develop together. Your dog will then consume a flea infected with the larval cysts, often while grooming or chewing at an itch. The larval cysts will break open and develop into adult worms. This complete life cycle takes 2-3 weeks.

Hydatid Worms and worms of the Taenia species have a variety of paratenic hosts, depending on the specific worm species involved. Possible hosts can include sheep, cattle, pigs, goats, rabbits and hares. Echinococcus granulosus can also use macropods, such as Kangaroos, as a paratenic host. Hydatid worms have a life cycle taking approximately 6-9 weeks.

The paratenic host will often consume the tapeworm eggs while eating grass that has been contaminated with dog faeces. The eggs will then hatch and the tapeworm larval stages will form cysts within the tissues, particularly muscles, of the host. Dogs will become infected by eating the raw meat that contains larval cysts, which will then develop into adult worms.

Unlike other tapeworms, the Zipper Worm (Spirometra erinacei) has at least two intermediate hosts. The first host is a small water based crustacean called Copepods. These are then ingested by the second intermediate host; frogs, snakes, lizards, chickens, pigs, birds, etcetera. This ingestion often occurs passively while they are drinking the water. Dogs can become infected via two methods:

They may drink contaminated water, becoming a secondary intermediate host. In this case the larvae develop into a new stage where they are called sparganum and these infect the dog's muscles and tissues as cysts.
They could consume the second intermediate host and become infected with adult worms, which reside in the intestinal tract.

The Zipper Worm's full lifecycle takes around 6-10 weeks (48-67 days), and like Hydatid worms, its adult form can survive within a cat for several years.