Bladder worm

General description

  • Bladder worms are large cysts found on the liver and in the abdominal cavity of sheep caused by the ingestion of eggs from the dog tapeworm Taenia hydatigena.


  • Sheep become infected by ingesting tapeworm eggs from contaminated pastures.

Clinical signs

  • Sheep will show no clinical signs.


  • Cysts cannot be detected in live animals but are readily seen by examining the animal at the abattoir.
  • Bladder worm cysts have a thin wall, are 1-6 cm in diameter and are filled with clear fluid.
  • They occur on the liver, diaphragm and abdominal organs and tissues.
  • Before cysts are formed, the migrating stages cause bloody tracts in the liver tissue.


  • There is no effective treatment for sheep with bladder worm cysts.
  • Treatment is not necessary as the cysts cause no economic or production loss and are not a human health risk.


  • Monthly worming of farm dogs, restricting them from access to offal and uncooked sheep meat will help prevent false hydatids.
  • Control wild dogs.

Learn more

Fact Sheet - Bladder Worm