Lungworm: What You Need to Know

Lungworm: What You Need to Know
18 March 2019
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Lungworm outbreaks are unpredictable and contrary to popular belief can affect all animals, not just youngstock - at any time of the year.

Lungworm is widespread in the UK, affecting a large number of herds - although many do not show clinical signs of the disease. During our travels this past autumn and winter we have seen many coughing animals. Following such a dry summer exposure was lower than normal, meaning animals in their first grazing season did not get the exposure to develop their own immunity, leaving them at greater risk this year. Animals exposed to lungworms usually develop resistance to re-infection. But the lack of exposure last year may result in clinical signs occurring in older cattle, including milking cows. Prognosis will vary according to the severity of the disease and deaths may occur despite treatment.

The costs associated to lungworm infection can equate to up to £140/adult dairy cow and £50-£100/beef cow in production losses, including milk drop and reduced growth rates. Treating an outbreak could cost you as much as £4.78 per animal!

The life cycle is similar to that of a gastrointestinal worm, but with one main difference; first stage larvae are coughed up and swallowed and then hatch during their passage through the gastrointestinal tract.

From consumption of the worms it can take up to four weeks for them to start laying eggs. It is important that you select the correct wormer that will kill all stages of the life cycle - otherwise you will need to worm them again!

Wormers can be used strategically in first-year grazing cattle to prevent build-up of lungworm larvae on pasture over the grazing season. but be careful not to overuse wormers as this could limit exposure to the lungworm larvae to such an extent that cattle remain susceptible to infection. If you do decide to treat then it is worth avoiding oral wormers in animals with respiratory distress, instead use a pour-on or injectable.

Clinical Signs

  • Widespread coughing in grazing animal
  • Loss of condition
  • Increase in respiratory rate
  • Difficulty breathing
  • Reduced milk yield in adult cattle

Lungworm immunity is maintained from season to season by the exposure to lungworm larvae, which in most cases occurs from the grazing of normal pastures after vaccination. However, if we have a particularly dry year and levels are low, cattle will not get the exposure they require to develop their own immunity.

Once cattle are infected, we can diagnose lungworm with faecal samples. It is a different test to the usual WEC, taking slightly longer as we have to look for the larvae, not the eggs. If your cattle are diagnosed with lungworm then most wormers will treat them, however not all wormers will kill all life stages. It is important that you speak to a vet before selecting a wormer so you can ensure you pick the most appropriate one.

To avoid infection in naïve animals you can vaccinate first year grazers, providing them with immunity before they are able to develop their own. There is only one vaccine available; Huskvac.

Huskvac contains irradiated larvae which can't fully develop. this allows the animal's immune system to kill off larvae, creating immunity against lungworm for long-term protection.

Lungworm has already been detected this year in youngstock, despite them being wormed at housing. It is so important that you choose the right wormer at housing otherwise you may find infections persist over winter and your youngstock are affected, even before turnout.

Top tips for preventing and treating lungworm

  • Consider vaccinating all first-year grazers
  • Test faeces of grazing cattle and treat any that are infected with appropriate wormers as early as possible to improve the response rate
  • Remove affected cattle from infected pasture
  • Overuse of wormers can prevent the development of natural immunity so contact us to discuss a control plan tailored to your farm

As always prevention is better than cure and working out a control strategy will save time and money. Lungworm outbreaks can cause severe losses and even death in cattle. This can happen at relatively low pasture infection levels. Farms with a previous history of lungworm should consider vaccination as an integral part of their overall worm control strategy as part of herd health planning.

Please call the practice today on 01934 852 650 to speak to a vet about setting up a control plan tailored to your herd.