Haemonchus Contortus: the Barber’s Pole Worm

May 17, 2024

Over the Summer and Autumn of 2023, we saw lots of cases of Haemonchus Contortus in sheep, goats, and alpacas. Haemonchus, also known as the Barber’s pole worm, lives in the abomasum of small ruminants, feeding on blood. Each worm can ingest up to 0.05ml/day, so a sheep with 5000 worms may lose 250ml of blood daily. Each adult female worm can produce 5,000-15,000 eggs a day, so high levels of infection can occur very quickly. This leads to anaemia, weakness, collapse, and death if left untreated. In more chronic cases, fluid builds up under the jaw (‘bottle-jaw’) and animals lose condition. Diarrhoea does not normally occur. Adult animals do not develop a strong immunity, so all ages are at risk. There is also evidence that the worm is adapting to climate change to survive at a wider range of temperatures, so vigilance is required all year round.

Monitoring for Haemonchus requires three key strategies:

1.Worm Egg Counts

Regular worm egg counts should be carried out to assess worm burden. Haemonchus usually presents with exceptionally high worm egg counts.

2.Body Condition Score

Regularly body condition score or weigh animals to identify weight loss as early as possible.

3.Eye Colour

Assess the degree of anaemia by examining the colour of the eye membrane. This can be scored with the FAMACHA© system from 1 (normal pink colour) to 5 (white indicating severe anaemia). This should be routine practice in all alpacas and goats, and carried out regularly in sheep if the farm is known to be at risk.

It is essential to worm in-coming animals whilst in quarantine to prevent introducing Haemonchus to the farm. Haemonchus can be treated with most broad-spectrum wormers, as well as narrow-spectrum products containing Closantel. To discuss this further please get in contact with Towcester Farm Vets and we will be happy to chat about a control strategy for your farm.

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