Why smart testing beats blanket dosing

I recently travelled the country and noticed growing interest in a parasite called Haemonchus contortus, or Barber’s Pole worm, writes Nerys Wright.

I’ve encountered it before in the south and east, recent queries have come from the Midlands and the north of England – suggesting it may be spreading

It’s easy to feel alarmed when you hear phrases like “it’s a new worm” or “it kills adult ewes.” But it’s important to keep things in perspective and view it as any other parasite.

Yes, outbreaks of haemonchosis (the disease caused by the parasite) can be serious, but it’s important to understand what we’re dealing with, treat only affected animals, and confirm that treatment has worked.

This blood-sucking roundworm lives in the sheep’s stomach and behaves differently from more familiar gut worms.

It typically doesn’t cause diarrhoea but can lead to anaemia, bottle jaw, weight loss, and, in severe cases, sudden death.

Warmer winters and dry springs may be helping it survive and spread, although the exact reasons are still unclear.

Crucially, the presence of Haemonchus eggs in a faecal egg count (FEC) doesn’t always mean disease is present.

That’s why accurate diagnosis is essential. Start with an FEC, then confirm with species identification using the peanut agglutinin (PNA) staining test via your vet, which shows the proportion of eggs that are Haemonchus.

FAMACHA scoring – checking the colour of the lower eyelid from red to white – is a useful on-farm tool for spotting anaemia. If a sheep dies suddenly, a post-mortem can confirm infection. Any treatment should be based on test results and your farm’s history of product use.

Finally, don’t assume resistance patterns in other worms apply. And remember Haemonchus has different resistance mechanisms. Always consult your vet, adviser or SQP for guidance.

Nerys Wright is an independent sheep consultant. For more details, call 07891 187643 or visit sheepconsultancy.co.uk.