Tapeworms of dogs and cats have indirect life cycles with adult tapeworms located in the animals' small intestine and the larval (metacestode) stage found in an intermediate host. Dogs and cats become infected by ingestion of the infected intermediate host. Most urban dogs and cats eat prepared foods and have restricted access to natural prey. Such animals still may acquire Dipylidium caninum (the double-pored dog tapeworm) by ingesting fleas during grooming. In many parts of the world, such infections appear to be common. Cats with access to infected house (or outdoor) mice and rats also can acquire Taenia taeniaeformis.
Suburban, rural, and hunting dogs have more access to various small mammals, in addition to raw meat and offal from domestic and wild ungulates. A number of cestodes can be expected in such dogs ( see Table: Cestodes of Dogs and Cats in North America Cestodes of Dogs and Cats in North America ) Globally, the two most important are Echinococcus granulosus sensu lato (the hydatid tapeworm) and Echinococcus multilocularis (the alveolar hydatid/fox tapeworm).
On sheep ranges and wherever wild ungulates and wild canids are common, dogs may acquire E granulosussensu lato. DNA analysis has indicated that E granulosus sensu lato is a species complex that comprises E granulosus sensu stricto (sheep/buffalo strains G1, G2, G3), Echinococcus equinus (horse strain G4), Echinococcus ortleppi (cattle strain G5), Echinococcus intermedius (camel strain G6, pig strain G7), and Echinococcus canadensis (cervid strains G8, G10). Dogs are definitive hosts for all these species. Furthermore, all except E equinus are a public health concern. E multilocularishas been found in wildlife in arctic North America, midwestern US, and southern Canada (British Columbia east to Ontario). The parasite is also endemic in many parts of central and eastern Europe, particularly France, Germany, and Switzerland, and in China.
Thus far, intestinal infections in dogs, and to a much lesser extent cats, are generally uncommon (< 1%); however, they are a noteworthy public health concern. Furthermore, in addition to developing intestinal infections from ingestion of infected rodents, dogs may develop alveolar echinococcosis (disease due to the larval stage of the parasite, typically in the liver) from ingestion of parasite eggs, eg, in feces of wild canids. Such infections, while uncommon, have been diagnosed in multiple dogs in central Europe, across southern parts of Canada, and in Virginia, US.
Spirometra mansonoides is an uncommon (but not rare) parasite of cats and occasionally of dogs along the eastern and Gulf Coast areas of North America and also parts of South America. Other species occur in Asia, Australia, and Europe. Infections are acquired by ingestion of the parasites' second intermediate host (amphibians, reptiles, birds).
In parts of southern Europe and the Middle East, cats with access to reptiles can become infected with Diplopylidium nölleri. In certain parts of the world (eg, India, the Middle East, North Africa, southeast Asia, southern Europe), dogs and cats with access to reptiles may acquire Joyeuxiella pasqualei.
Association with infected dogs may result in human infection with metacestodes of E granulosus, E multilocularis, Taenia multiceps, Taenia serialis, or Taenia crassiceps in various tissues (by ingestion of eggs passed in dog feces), or adult D caninum in the intestine (by ingestion of infected fleas). The presence of metacestodes in production animals may limit commercial use of such carcasses or offal meats. Thus, cestodes of dogs and cats may be of both economic and public health importance ( see Table: Cestodes of Public Health Importance Cestodes of Public Health Importance ).
Clinical Signs of Tapeworms in Dogs and Cats
Adult cestodes in the intestine of dogs and cats rarely cause disease, and clinical signs, if present, may depend on the extent of infection, age, condition, and breed of host. Clinical signs vary from unthriftiness, malaise, irritability, capricious appetite, and shaggy coat to colic and mild diarrhea; rarely, intussusception or blockage of the intestine, emaciation, and seizures occur.
Diagnosis of Tapeworms in Dogs and Cats
Diagnosis of tapeworm is based on finding proglottids or eggs in the feces. However, all fecal flotation methods have low sensitivity. It should also be noted that the eggs of Taenia spp and Echinococcus spp cannot be differentiated by microscopic examination; PCR assay methods are required. Fecal sedimentation or fecal flotation may reveal the eggs of Diphyllobothrium or Spirometra spp, which, unlike more common tapeworms, lack hooks; they are sometimes mistaken for trematode eggs, although they are larger and possess an operculum that is often difficult to see.
In some parts of the world, fecal antigen tests for Echinococcus spp are available.
Treatment and Control of Tapeworms in Dogs and Cats
Control of tapeworms of dogs and cats requires treatment and prevention. An accurate diagnosis is necessary for effective advice on preventing reinfection. Animals that roam freely often become reinfected by ingestion of metacestodes in carrion or prey animals. D caninum is different, because it can cycle through fleas that may be associated with confined infected animals.
Effective treatment includes removal of the attached scolices from the small intestine of infected animals. ( See table: Cestodes of Dogs and Cats in North America Cestodes of Dogs and Cats in North America for specific approved treatments.)
For dogs: 1) fenbendazole and praziquantel are approved for treatment of Taenia spp; epsiprantel is approved for just Taenia pisiformis; 2) epsiprantel, nitroscanate, and praziquantel are approved for D caninum; and 3) praziquantel is approved for treatment of Echinococcus spp ( see Table: Drugs for Intestinal Helminths of Dogs Approved in the US and UK Drugs for Intestinal Helminths of Dogs Approved in the US and UK ).
For cats: 1) fenbendazole and praziquantel are approved for treatment of Taenia spp; epsiprantel is approved for just T taeniaeformis; 2) epsiprantel and praziquantel are approved for treatment of D caninum; and 3) praziquantel is approved for treatment of E multilocularis ( see Table: Drugs for Intestinal Helminths of Cats Approved in the US and UK Drugs for Intestinal Helminths of Cats Approved in the US and UK ).
Outside the US and UK, praziquantel is approved for use in multiple countries at 5 mg/kg for treatment of J pasqualei in dogs (as praziquantel/pyrantel/febantel) and cats (as praziquantel/pyrantel). In the UK, EU, India, and other countries, praziquantel is approved at 10 mg/kg for treatment of J pasqualei and Joyeuxiella fuhrmanni in cats (as praziquantel/eprinomectin/fipronil/methoprene topical). In India, the same praziquantel dosage/combination product is also approved for treatment of Diplopylidium spp in cats.
Praziquantel at 7.5 mg/kg, PO, for 2 consecutive days is effective against Diphyllobothrium sp in dogs. If this does not eliminate the infection, a single dose of 35 mg/kg, PO, should be administered. A single dose of 35 mg/kg, PO, eliminates Diphyllobothrium latum from infected cats. 1 References D caninum segments found in the feces of a dog. Bar = 1 cm. Note barrel shape and two lateral pores per segment (arrows). E granulosus sensu lato tapeworm found in the small intestine... read more All treatments are extra-label.
Infections with Spirometra sp in dogs and cats can be treated with praziquantel at 7.5 mg/kg, PO or SC, for 2 consecutive days. Spirometra sp infections in dogs and cats can also be treated with praziquantel at 25 mg/kg, PO, daily for two consecutive days. All these treatments are extra-label.
In 2018, resistance to praziquantel and epsiprantel at approved dosages was described in D caninum in multiple US states. Infections were eliminated using nitroscanate or pyrantel/praziquantel/oxantel at approved dosages.
Prevention of Tapeworms in Dogs and Cats
For dogs and cats at high risk of developing intestinal infections with Taenia spp, praziquantel may be administered at the approved dosage every 3–6 months as a preventive. In regions where E granulosus sensu lato is a concern, dogs at risk of developing intestinal infections (eg, by ingestion of internal organs of ruminants) can be treated every 6 weeks with praziquantel at the approved dosage to prevent shedding of eggs in the environment. In regions where E multilocularis is a concern, dogs at risk of developing an intestinal infection (ie, by ingestion of infected rodents) can be treated every 4 weeks with praziquantel at the approved dosage to eliminate the public health concern. High-risk cats can be treated similarly. However, the risk of human infection from infected cats is considered much less than with infected dogs.
AAVP and Sakamoto T. 1977. The anthelmintic efficacy of Droncit on adult tapeworms of Hydatigerataeniaeformis, Mesocestoidescorti, Echinococcusmultilocularis, Diphyllobothriumerinacei, and D. latum. Vet Med Rev 1:64–74.
For More Information
Deplazes P, Eckert J, Mathis A, von Samson-Himmelstjerna G, Zahner H. 9.3 Class Cestoda (tapeworms). In: Parasitology in Veterinary Medicine. Wageningen Academic Publishers; 2016:206–253.
Bowman DD. Class Cestoidea. In: Georgis’ Parasitology for Veterinarians. Elsevier;2021:151–170.
Bowman DD, Hendrix CM, Lindsay DS, Barr SC. The Cestodes. In: Feline Clinical Parasitology. Iowa State University Press; 2002:183–231.
Adolph CB, Peregrine AS. Tapeworms. In: Sykes J, ed. Greene’s Infectious Diseases of the Dog and Cat. 5th ed. Elsevier; 2022.