The Risk of Nematodirus

Nematodirus is a horrible disease affecting lambs that often results in high numbers of mortalities. It is particularly prevalent around this time of year. We explain how it is treated and can be prevented.

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Nematodirus is a horrible disease affecting lambs that often results in high numbers of mortalities. It is particularly prevalent around this time of year.

What Causes Nematodirus?

It is caused by the Nematodirus battus parasite and leads to large amounts of watery diarrhoea. Nematodirus is a type of worm and commonly affects young lambs that have never been exposed previously and therefore have no natural immunity.

What Symptoms Should I Look Out For?

  • Sudden, profuse diarrhoea.
  • Dehydration (look out for lambs gathering around water trying to rehydrate).
  • Faecal staining of tail and perineum.
  • Rapid loss of body condition.
  • Lambs that stop sucking.
  • Depressed looking lambs.

How is Nematodirus Spread?

The disease will pass from sheep to sheep via pasture in the same grazing season.

From ingestion, infected larvae will go on to develop in to adult worms (that can lay eggs) in as little as 14-21 days. The eggs laid by the adult worms will pass through the faeces, resulting in greater contamination of the pasture.

Weather conditions have an impact on how soon your flock will be affected. The eggs will either develop in to infected larvae that will infect lambs immediately, or lie dormant until the next Spring, infecting next season’s lambs.

This makes the disease extremely difficult to control.

When Am I At Most Risk?

There are two key factors to consider when assessing the risk of nematodirus:

  • Climatic Conditions: a sudden change from cold frosty mornings to a period of warmer weather can trigger the mass hatching of eggs.
  • Lamb Age: lambs that are old enough to be eating large amounts of grass (6-12 weeks old)

Treatment of Nematodirus

The best course of treatment is a group 1 wormer (white/1-BZ), which is recommended by SCOPS.

For the treatment of lambs, be sure to weigh them and dose accordingly to ensure the course of treatment is effective.

You should also take faecal worm counts 7-10 days after treatment to gauge the effectiveness of the treatment administered.

We are now stocking Endospec 2.5%, the treatment for Nematodirus

 

How Do I Prevent My Sheep From Getting Nematodirus?

We advise that you follow these three steps

  1. Keep an eye on the parasite forecast in your area, and be ready to act at the right time.
  2. Local knowledge on risk in your area is highly valuable. Keep in contact with your local vets and SQPs.
  3. Avoid grazing lambs on the same pasture on consecutive years.

 

If in doubt, always speak to your local vet.

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