Tapeworms of the Dog

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This Vet Note is specific to Dipylidium caninum.

What is it?

Cestodiasis is a parasitic infection of the small intestine caused by cestodes (a.k.a. tapeworms), which are segmented intestinal parasitic flatworms. 

Dipylidium caninum is the most common tapeworm of the dog. 

Note that there are additional tapeworm species e.g. Taenia spp. and Echinococcus spp., but this Vet Note is specific to Dipylidium caninum.

For Dipylidium caninum to be infectious in dogs, it has to first pass through an intermediate host: the dog or cat flea (Ctenocephalides spp.), or less frequently through the dog louse (Trichodectes canis). The reason an intermediate host is required is for completion of the tapeworm life cycle. Dipylidium caninum is therefore commonly referred to as the flea tapeworm of dogs and cats.

Where can it be found?

It can be found worldwide.

How does infection occur?

Infected dogs pass egg-filled proglottids (gravid proglottids) through their feces into the environment. Gravid proglottids can also migrate to the dog’s perineal region. The gravid proglottids dry out and disintegrate, releasing their egg packets into the environment, where a flea larva (immature flea) ingests it. Eggs release tapeworm embryos in the flea’s intestines which then develop into tapeworm larvae as the flea larva matures into an adult flea. The adult flea harbors the infective tapeworm larvae. Another dog can then become infected by ingesting a larval infected adult flea, or less frequently a larval infected louse (indirect life cycle). 

What are the clinical signs?

It is commonly asymptomatic (has no clinical signs). If there are clinical signs, clinical signs include motile or dried white to gold colored proglottid (“rice grain”, “cucumber seed”, or “sesame seed”) in the perineal region or on the feces, with perianal irritation and pruritus, which commonly presents as excessive grooming of the perineum and dragging the perineum across the ground (“scooting”), and is due to proglottids getting stuck to the fur in the perianal region. Heavy infestations can however cause diarrhea, weight loss, failure to thrive, poor coat, abdominal pain, intestinal obstruction, and vomiting. Migration to the stomach may occur occasionally, which could result in the dog vomiting an adult tapeworm several inches long.

How is it diagnosed? 

It is commonly preliminarily diagnosed based on clinical signs and/or identifying the proglottids on or in the feces, in the perianal region, or on the pet’s bedding. Diagnosis can also be made via microscopic exam of a crushed proglottid, PCR (polymerase chain reaction), and rarely via fecal flotation. 

Freshly passed proglottids are white, moist, soft, motile, and look like cooked grains of white rice or cucumber seeds that are crawling. 

Dried proglottids are hard, golden in color, not motile, and look like sesame seeds.

What are the treatment options?

Some of the medications your veterinarian may prescribe are praziquantel, epsiprantel, or a combination product.

Only a single treatment with one of the above anthelmintic medications is required. Sometimes however, a repeat treatment in approximately 3 weeks is recommended, most notably when there is a significant flea infestation due to risk of reinfection by ingesting another larval infected adult flea.

Part of the treatment protocol should include flea control. The patient and all pets in the household should be placed on a good quality monthly flea prevention, as well as treating the environment.

Monitor for proglottids following treatment.

How can it be prevented?

Prevention consists of keeping dogs on good quality monthly flea prevention.

Can my dog infect humans or cats?

Zoonosis (infectious disease transmissible from non-human animals to humans) is possible, but not directly from your dog; a human must ingest a larval infected adult flea or less frequently a larval infected louse for infection to occur, making risk of infection in humans low. Similarly with cats; cats must ingest a  larval infected adult flea or less frequently a larval infected louse for infection to occur.

For Veterinary Professionals, refer to our app, VetpocketTM, for more in depth reference material including treatment dosing guidelines.

*Disclaimer: The information is not intended to replace clinical judgment or guide individual care in any matter. Please check any information and values prior to use and use at your own risk.