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Lungworm

Lungworm

Lungworm (or Husk) is a parasite that lives in the lungs and respiratory tract. It typically occurs at the end of summer after a season of grazing. Cattle of all ages can be affected, depending on previous exposure to the disease.

The lungworm lifecycle can last up to 4 weeks, by which time the cow can shed over a million larvae per day onto the pasture. Ingested larvae travel down to the intestines and after a week start migrating to the lungs. There they develop into adults causing clinical disease. Eggs are then coughed up and swallowed, hatching on the way down and being shed as larvae in the faeces. 

By the time clinical disease is obvious, the animal may have had up to 3 weeks of infection. This means that by then, the lung function can be severely compromised.

Early clinical signs include:

  • Increased respiratory rate
  • Soft cough – particularly after exercise
  • Milk drop and reduced fertility

 

 

This then progresses to more severe disease, with the animal’s neck outstretched, frequent coughing and even death.

In a straight case of lungworm, there will be no temperatures and little nasal discharge. Occasionally  

infection is complicated by a bacterial pneumonia when you may see these signs.

Prompt anthelmintic treatment (wormer) is necessary to kill off the worms. All modern wormers will do the trick and choice is normally made on route of administration and withdrawal. Milking cows should be treated with Eprinex® as it has no milk withdrawal.

Often the clinical signs persist after treatment as the cow has to cough up the dead worms. To ease the signs, anti-inflammatories such as Ketofen® or Finadyne® can be used. If a secondary bacterial infection exists this can be treated with Engemycin®. 

The best way to control lungworm is (as always) by prevention.

Vaccination is the most effective control measure. This involves two doses of inactivated larvae given to heifers orally. The second of these two doses is given at least two weeks before turnout to ensure good immunity.

As the vaccine contains inactivated larvae, wormers should not be given at the same time. Sustained release wormers may be given two weeks after as the animal’s immunity should be complete by then.

After the initial year of vaccination, the cows’ immunity should be enough to control the worm burden. However, in particularly warm and wet years disease can be seen in adult animals as the pasture burden becomes high.

For advice on lungworm or worming protocols please speak to Tonia or Euan.