The Farmers Mart Feb-Mar 2019 - Issue 61 | Page 20
20 FARM NEWS
FEB/MAR 2019 • farmers-mart.co.uk
WATCH OUT FOR FLUKE, PARASITIC
GASTROENTERITIS, SCAB AND LICE
Final assessments from NADIS confirm that the overall risk of liver fluke is low in the UK, except for south west Scotland
which has been classified as ‘medium’. However, abattoir feedback shows fluke is being regularly detected.
THE forecast is based on rainfall
and temperature data from May
to October 2018; but local condi-
tions may still allow fluke and its
intermediate host (the mud snail
Galba truncatula) to develop to
levels that pose a threat to cattle
and sheep.
Cattle with chronic infections,
associated with the presence of
mature fluke in the bile ducts of
the liver, may show no obvious
signs, but fertility and productivity
may both be impaired. In addi-
tion, a fluke infection can make
stock vulnerable to other condi-
tions such as Black disease which
can be fatal.
As fluke risk is highest on damp,
muddy pasture, farmers with-
out-wintered stock should choose
pastures with care.
Stock should be monitored for
signs of infection. Where animals
have been at risk grazing wet pas-
tures, body condition scoring and
diagnostic testing of faecal sam-
ples can provide an assessment of
whether treatment is warranted.
Where acute fluke infection is
found in sheep, treatment with tric-
labendazole is recommended. This
is the only product effective against
immature stages of the parasite
which cause the most damage and
production loss in sheep.
Later in the season, when
chronic infection poses the
greatest risk, alternatives to
triclanbendazole are available to
treat both cattle and sheep. The
use of products containing active
ingredients such as nitroxynil and
closantel at or during housing can
help remove the impact of fluke
on productivity. Retreatment later
in the housing period or diagnos-
tic testing to check whether ani-
mals have a residual fluke burden,
and retreatment if indicated, will
ensure livestock are turned out
fluke free and do not shed eggs
onto the pasture.
Given concerns over emerging
anthelminitic resistance, testing
for treatment efficacy through
pre- and post-treatment diag-
nostics is also advised.
Sheep farmers need to remain
vigilant for parasitic gastroenteri-
tis (PGE)
The larvae of many dis-
ease-causing roundworms,
particularly Trichostrongylus
species, may continue to be a
risk in store and replacement
lambs and, sometimes, yearlings
into the winter. Sheep grazing
potentially contaminated pas-
ture should be monitored.
As the weather becomes
colder, newly acquired larval
infections of roundworm species
(including Haemonchus and
Teladorsagia) will begin to encyst
and can provide an important
source of pasture contamina-
tion next spring. An appropriate
treatment administered at the
end of the grazing season, or
once animals are housed, can
remove arrested larval stages
and reduce the potential for
pasture contamination and
re-infection at lambing. Suitable
products are available across
all major worming groups and
advice from a vet or an SQP on
product choice is recommend-
ed.
Scab and lice also pose threats
to sheep overwinter. While
symptoms are similar, treat-
ments are different as scab mites
live under the skin and lice thrive
in the fleece.
Infestations of psoroptic mites
(Psoroptes ovis) cause sheep
scab and lead to loss of condi-
tion, secondary skin infections
and potentially death if not
treated. Signs include severe
itching, wool loss, restlessness,
biting and scratching of affected
areas and weight loss or reduced
weight gain. Fleece may be wet,
sticky and yellow, while the skin
may become thickened and
corrugated. Diagnosis can be
confirmed by microscopic anal-
ysis of skin scrapings, or through
an ELISA test.
Louse infestations are typical-
ly caused by the chewing lice
Bovicola ovis. Lean or emaciated
sheep tend to be most greatly
affected. Lice can sometimes be
detected with the naked eye and
confirmed by examination with a
microscope.
Louse infestations can be
controlled with topical products
containing synthetic pyrethroids
which are most effective on
shorn sheep.
Both scab and louse infes-
tations can be controlled by
plunge dipping with diazinon.
www.boehringer-ingelheim.com/
animal-health/overview