Knotty Gut (nodule worm/pimply gut)

General description

  • Oesophagostomum columbianum (nodule worm) is a large (20 mm) white stout worm.
  • The parasite occurs in the summer rainfall areas.
  • Nodule worms live in the large intestine of the sheep and cause damage to the lining of the gut which can no longer be used for sausage casings and suture material.


  • Sheep grazing close to the soil surface ingest the infective larvae.

Clinical signs

  • Nodule worm, if present in numbers, causes severe disease. Sheep, particularly weaners, show ill-thrift, often standing with a characteristic humped back, they lose condition, become weak and scour intermittently.


  • Eggs in faeces are similar to those of other nematodes.
  • Worms identified at slaughter.


  • Many of the sheep drenches are registered for the treatment of nodule worms.


  • Ensure an adequate drenching program is carried out regularly.
  • Avoid use of contaminated pastures.

Learn more

Fact Sheet - Knotty Gut