Knotty 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.
- The larval stages cause damage to the lining of the gut (which can no longer be used for sausage casings and suture material).
- The adult worms can damage the colon in severe infestations leading to ulcers and bloody scours.
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.
Cause
- columbianum prefers warm, wet conditions (summer rainfall). Cold and dry conditions are not conducive to egg and larvae survival on pasture.
- Sheep grazing close to the soil surface ingest the infective larvae.
Diagnosis
- Eggs in faeces are like those of other nematodes.
- Worms identified at slaughter.
Treatment
- Many of the sheep drenches are registered for the treatment of nodule worms.
- However, existing nodules persist as scars that can lead to condemnation of runners.
Prevention
- Ensure an adequate drenching program is carried out regularly.
- Avoid use of contaminated pastures.
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