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By this I mean vaccination - Huskvac is one of the oldest vaccines on the market but it is still really effective - like most vaccines you do have to allow enough time for the immune system to respond to the vaccine before you expose the stock to the risk. Two doses need to be given 4 weeks apart with the last dose two weeks before turnout, so before you know it the sun will be shining and you'll want to be putting those calves out!

Controlling lungworm should be considered separately from gutworm control, although wormers which kill one will kill the other. The main difference in control is that it takes relatively few lungworm to cause infection compared to gutworms (less than 1,000 lungworm larvae versus over 10, 000 for gutworm infection). This means that pastures can very quickly change from low risk to high risk. The worms come out in the dung as first stage larvae, rather than eggs and need quite a heavy rainfall to be released out on the pasture to get eaten which is why problems can suddenly appear after wet weather. They are also helped out by a little fungus (which you may have seen photos of before) which the lungworm crawl up onto and then get flung in the air when the top of the fungus bursts open to spread its spores.

 

Sadly, faecal egg counting is no use for predicting a brewing problem as it is for gutworm, as the lungworms start irritating the lungs before they start producing eggs. Additionally the worms come out in the dung as larvae not eggs, which means that we have to do a completely different lab test to find them and try to use samples from calves that have been infected for a while. We have the option of blood samples to look at antibody levels to see if stock have been exposed to lungworm but as it takes a while to make antibodies to fight off problems these will often come back negative if taken in the early stages of disease.

This means that diagnosis is often by the typical symptoms. Coughing is the first sign you'll see, but it does indicate that lung damage is already occurring. A small percentage of animals (1-2%) may have a more severe, allergic-type of reaction to the lungworms and have an acute respiratory problem and/or die.

So perhaps I'm over complicating something that most farmers control almost incidentally whilst worming cattle for gutworms? The problem is that our unpredictable weather along with some over keen worming strategies can brilliantly control both types of worms in young stock - but leave them with little immunity to protect them for the rest of their lives. And unfortunately the older an animal is when it gets ill with lungworm the worse it often seems to hit it plus it is very costly if milk yield crashes in a dairy herd.

At Westpoint Veterinary Group  we have found that reviewing parasite control has reduced the amount of wormers used for most herds - don't get too influenced by what's on special offer over the counter; talk it through with your vet!

Rachel Risdon BVSc CertCHP MRCVS