Haemonchus contortus in Sheep: Barber's Pole Worm Welfare

Haemonchus contortus is the most pathogenic gastrointestinal parasite of sheep. This guide covers welfare impacts and sustainable control.

Key Facts

Haemonchus contortus (barber's pole worm) sucks blood from the abomasal wall
Even moderate burdens cause anaemia, bottle jaw, weakness, and death
It is the leading cause of sheep mortality from parasites in warm, humid climates
Anthelmintic resistance is widespread, reducing treatment options
FAMACHA scoring enables targeted treatment of clinically anaemic animals
Refugia-based management preserves anthelmintic efficacy for future generations

Welfare Considerations and Management

Welfare-centred Haemonchus management requires balancing effective treatment with anthelmintic stewardship. FAMACHA (anaemia assessment by eye membrane colour) enables targeted selective treatment of animals with clinically significant anaemia, preserving refugia in untreated animals. Worm egg count monitoring guides treatment decisions. Effective anthelmintics should be used at correct doses. Pasture management reduces infection pressure. Breeding for worm resistance (using DAG scores and worm egg counts) offers long-term genetic solutions.

What You Can Do

Learn to use FAMACHA scoring for targeted treatment of anaemic sheep
Monitor worm egg counts to guide treatment decisions rather than routine dosing
Use anthelmintics correctly and rotate classes to manage resistance
Consider selecting for worm resistance in your breeding programme