Fox Tapeworm Infection (Cysticercosis) in Dogs


PetMD Editorial

Published Apr. 26, 2010

Cysticercosis in Dogs

Cysticercosis is a rare disease caused by the larvae Taenia crassiceps, a type of tapeworm. Once the eggs (which is suspected to be found in the feces of infected foxes) are ingested by rabbits or other rodents, it develops in the abdominal and subcutaneous tissues, and eventually forms large masses of cysticerci (larval form) in the abdominal cavity, lungs, muscles, and in the tissues under the skin. Even worse, the cysticercus is capable of undergoing asexual reproduction and multiplying a high rate.

It is rarely reported in Europe or the United States, but often occurs in olders dogs or young immuno-compromised pups.

Symptoms and Types

Cysticerci masses may found under the skin or in other organs, causing several complications including:

  • Anemia
  • Loss of appetite (anorexia)
  • Respiratory distress (when found in lungs)
  • Yellowish skin (when found in abdominal cavity)


Mode of infection not clear, but three are hypothesized:

  • Ingestion of parasite eggs found in feces of an infected fox (possibly a coyote)
  • Autoinfection, whereby the dog reinfects itself by eating its own feces which contain Taenia crassiceps eggs
  • Ingestion of the Taenia crassiceps in its larval stage (cysticercal)



You will need to give a thorough history of your dog’s health to your veterinarian, including the onset and nature of the symptoms. He or she will then perform a complete physical examination as well as a complete blood count, biochemistry profile, urinalysis, and electrolyte panel. X-rays will help to determine the degree of spread to the internal organs, and an ultrasound will differentiate these masses from cancers, which are solid.


Surgery is necessary to remove the larval masses. However, depending on how severe the secondary symptoms are, your veterinarian may need to stabilize and hospitalize the animal first.

Living and Management

Fortunately, the stages in which dogs display clinical signs are not zoonotic, so owners should not fear of contracting the worms from his or her dog. However, your veterinarian will schedule follow-up appointments to examine the dog and monitor (often with abdominal ultrasounds) for the potential spread of lesions and the development of new lesions in different sites.

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