Tapeworms
Cyclophyllidean Cestodes*
CAPC Recommendations:
Intestinal Parasites: Cestodes:
Tapeworm (Cyclophyllidean Cestodes*)
Species
Canine
Dipylidium caninum, Taenia crassiceps, Taenia hydatigena
Taenia multiceps, Taenia pisiformis, Taenia serialis
Echinococcus granulosus, Echinococcus multilocularis
Feline
Dipylidium caninum, Taenia taeniaeformis, Echinococcus multilocularis
*Canine and feline cyclophyllidean cestodes are sometimes referred to as “true” tapeworms.
Overview of Life Cycle

Cyclophyllidean cestodes have indirect life cycles that require specific intermediate hosts. Dogs
and cats infected with adult cyclophyllidean tapeworms shed egg-laden proglottids in their
feces. When the eggs are consumed by the appropriate intermediate host, larval cysts
develop. Dogs and cats are infected when they ingest these larval cysts.
Stages

The infectious egg shows the hooks that are characteristic of a cyclophyllidean cestode
embyro.

Examples of larval cysts of cyclophyllidean cestodes include:
o compact cysticercoid, an immature form of the tapeworms that use an arthropod
intermediate host
o bladder-like cyst (referred to as a cysticercus) found in tapeworm species that use a
vertebrate intermediate host
o large, bladder-like coenurus, found in some tapeworm species (e.g., T. multiceps)
o large, thick-walled unilocular hydatid cyst of E. granulosus
o large, thin-walled alveolar hydatid cyst of E. multilocularis


Proglottids are shed in the feces of an infected dog or cat.
Adult cyclophyllidean cestodes are found in the small intestine of an infected dog or cat.
Disease

Disease in dogs and cats due to infection with adult cyclophyllidean cestodes is rare. Passage
of proglottids may be associated with perianal irritation.
Prevalence

The reported prevalence of tapeworms in published studies varies from 4.0% to 60.0% in
dogs and 1.8% to 52.7% in cats. A number of factors influence the likelihood that a dog or cat
will be infected with tapeworms, including the geographic region and the opportunity the
animal may have to ingest an infected intermediate host. Prevalence data generated by fecal
flotation alone almost certainly underestimate the frequency of infection with cyclophyllidean
cestodes because proglottids (and thus eggs) are focally distributed in fecal material; a given
fecal sample may be negative for tapeworm proglottids or eggs, even in the presence of an
infection.

Dipylidium caninum and Taenia spp. are found throughout North America. Currently,
Echinococcus spp. are thought to be largely limited to areas of the northcentral, midwestern,
and southwestern United States as well as areas of Canada and Alaska.
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Host Associations and Transmission Between Hosts

Both dogs and cats are susceptible to infection with D. caninum following ingestion of infected
fleas or, more rarely, lice (Trichodectes canis).

Echinococcus multilocularis will infect both dogs and cats following ingestion of rodents with
alveolar hydatid cysts.

Echinococcus granulosus and T. pisiformis are known to infect only dogs and wild canids.
Infection of dogs occurs following ingestion of cysts in ungulate viscera or rabbit tissue.

Taenia taeniaeformis infects only cats and wild felids and is acquired by ingestion of infected
rodents.
Prepatent Period and Environmental Factors

Dogs and cats may begin shedding proglottids of D. caninum, the common flea tapeworm, as
soon as 2 to 3 weeks following infection. For Taenia spp. and Echinococcus spp., the prepatent
period may be as long as 1 to 2 months.
Diagnosis

Diagnosis of infection with “true” tapeworms is reached by identifying proglottids in the fecal
material or by recognizing eggs on fecal flotation. However, because proglottids are not
uniformly distributed in the fecal material, fecal flotation alone is not a reliable means of
diagnosing tapeworm infection in dogs and cats.
Treatment

Praziquantel, epsiprantel, and fenbendazole are approved for the treatment of tapeworm
infections in dogs and cats.

Praziquantel and epsiprantel are considered the treatments of choice because they are highly
effective against D. caninum, the most common tapeworm of dogs and cats, as well as Taenia
spp. and Echinococcus spp.


Only praziquantel is labeled as effective against Echinococcus spp.
Treatment of tapeworms in dogs and cats must be combined with appropriate husbandry
modifications, such as effective flea control and prevention of ingestion of prey species; in the
absence of these changes, reinfection is likely to occur.
Control and Prevention

Stringent adherence to controlling fleas and lice is required to prevent D. caninum in dogs and
cats.

Prevention of predation and scavenging activity by keeping cats indoors and dogs confined to
a leash or in a fenced yard will limit the opportunity for dogs and cats to acquire infection with
Taenia spp. or Echinococcus spp. via ingestion of cysts in intermediate hosts.

Treatment of infected animals to remove tapeworms should be instituted simultaneously with
flea-elimination programs and predation prevention to avoid reinfection.

To prevent zoonotic infections with Echinococcus spp. in areas where this parasite is endemic,
routine monthly deworming of dogs and cats with praziquantel may be indicated.
Public Health Considerations

Echinococcus spp. infections are rare in humans in North America, and isolated reports of
zoonotic infection with larval Taenia spp. of dogs and cats also exist. Although the overall risk
of human infection with these parasites in North America appears extremely low, dogs and
cats infected with these tapeworms do create a potential zoonotic risk. The eggs shed in the
feces of an infected dog or cat are immediately infectious to the intermediate host. People who
consume these eggs may develop cestode cysts requiring drainage, surgical removal, and/or
extended chemotherapy. In the case of E. multilocularis, surgery is unlikely to be successful,
and long-term anthelminthic therapy may be required.

Infections of children with D. caninum following ingestion of an infected flea are occasionally
reported. The disease induced in the child is generally mild, confined to the intestinal tract,
and readily treated, but can still be distressing to the family.
www.SouthAndersonVet.com
109 W 53rd St * Anderson, IN 46013 * (765) 642-8117 * Fax: (765) 642-0519