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LUNGWORM PREVENTION
WORKING
TOGETHER
FOR A HEALTHIER FUTURE...
17
LIVESTOCK MATTERS
Traditionally, the time to start considering husk (lungworm) prevention is just before turnout. Given that
lungworm still remains a constant threat year on year, and turnout will be starting in some parts of the
country soon, planning how best to protect stock from the continued threat of lungworm will pay
dividends as the season progresses. Although outbreaks are seen mainly in late Summer and Autumn
(see graph below), early planning is the key to prevention.
Time to protect valuable
stock from
Lungworm...
Historically, lungworm problems have
been most commonly associated with
youngstock, but now almost 75% of
reported cases are in adult animals,
which could have a very significant
impact on the profitability of a herd.
Iain Richards from the Westmorland
Veterinary Group based in Kendal believes
the re-emergence of husk as a disease in
recent years is largely down to a reduction
in vaccination and changes in modern
worming practices.
‘When I first qualified 20 years ago you
just didn't see husk problems in cattle,
largely because vaccination was much more
prevalent. But around 10 years ago we
started to see it appearing again and it
can only be because current lungworm
control regimes are not working well enough.
If all you are going to use to worm your
cattle is a long-acting wormer with no
immunity development opportunities, it
could easily compromise your lungworm
control,’ he warns.
Westmorland Veterinary Group takes an
active interest in parasitology within the
practice. ‘We need to start taking a similar
approach with cattle as we do with sheep
under the SCOPS regime, and try not to
worm unless you have to. Recently, we've got
quite adept at finding evidence of lungworm
infections in cattle. The test is a little fiddly,
but quite straightforward, and we can have
a result overnight. And showing evidence
of the presence of lungworms does help to
convince farmers to implement a vaccination
regime,’ Iain says.
Iain maintains that planning lungworm control
strategies prior to a heifer's first grazing
season makes sense and doing so can
avoid the all-too-common scenario where an
infestation does occur later in the season
and treatment has to be given.
‘As well as being costly, lung damage will
often have already occurred, leading to the
typical signs we see in infected animals. In
youngstock the main effect is a depression in
growth rates, leading to a longer finishing
period or time to first service. In older cattle
the disease can depress milk yields and
depress fertility.’
Husk occurs as a result of infection with the
lungworm Dictyocaulus viviparus. Cattle
develop it after eating grass contaminated
with infective larvae. Once in the gut, the
larvae migrate through its wall and a few
weeks later reach the lungs where they begin
laying eggs. A spell of mild, wet weather can
create a sudden, dramatic increase in
lungworm populations, which can be very
harmful, even fatal, to any stock that have
little or no immunity.
‘Even where prevention is the goal, relying on
wormers alone doesn't allow the animal to
develop its own natural immunity,’ Iain Richards
says. ‘Ideally, at the start of the season you
should sit down with your vet and plan your
herd worming strategy, but controlling husk
should be the number one priority. Vaccination
with a pre-turnout course of Bovilis Huskvac
®
is the most reliable way of ensuring the
development of immunity to lungworm. When
you consider how much is invested in cattle
genetics, and the value of 24-30 month old
heifers, in particular, it makes no sense at all
not to vaccinate against lungworm when the
vaccine is such an effective product.’
Bovilis Huskvac is a live vaccine, made
from irradiated larvae, which are incapable
of causing disease. For dairy calves,
vaccination should be completed at least
two weeks before the calves are turned
out to grass, for suckled calves it should
finish two weeks before the calves begin
to eat significant amounts of grass.
Sustained-release wormers such as boluses
should not be given until two weeks after the
final dose of vaccine.
The vaccine produces a very good immune
response against disease but it does not
prevent all worms from natural infections
completing their life cycle. This allows for the
continued development of natural immunity,
which often fails to occur where there is an
over-reliance on wormers.
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Coughing cow