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SCHMALLENBERG VIRUS
WORKING
TOGETHER
FOR A HEALTHIER FUTURE...
9
LIVESTOCK MATTERS
Congenital defects of Schmallenberg virus
The most significant losses from SBV that
are seen this year will be as a result of
deformed calves and lambs born in the
spring. These defects arise as a result of the
cow or ewe becoming infected with the
virus during pregnancy. It is thought that the
danger time during pregnancy in the cow is
between the second and fourth months
of gestation, while in the ewe it is from the
first to the second months of pregnancy.
What we then see as a result of this
is the birth of deformed calves and
lambs. There are five main defects.
1.
Arthrogryposis
This means the joints are fused and
cannot bend. It mainly occurs in the hind
limbs and will often result in a difficult
calving or lambing (dystocia), because of
the inflexibility of the limbs. The calf or
lamb is usually dead in this situation.
3.
Scoliosis
This refers to a curve in the spine. These
will probably be born without assistance.
4.
Brachygnathus Inferior
This condition is where the lower jaw is
considerably shorter than the upper jaw.
It is also referred to as parrot jaw.
5.
Brain Hypoplasia
In this situation there is lack of development
of parts of the brain. It will result in birth of
a dead calf or lamb, or a severely brain
damaged offspring, which will not survive.
2.
Torticollis
This is where the neck is bent and again
is fused and inflexible. This will also
frequently result in dystocia which may
have to be resolved by Caesarean section
or by embryotomy, where the head is
removed by a protected wire saw.
Again the foetus is usually dead.
On your farm
In Cheshire and Shropshire, every dairy herd
in the XLVets survey tested positive for the
Schmallenberg virus.
However, Charlie Lambert from Lambert
Leonard and May Vet Group on the
Cheshire/Shropshire border warns farmers
not be too quick to blame the virus for every
abortion case.
He explains: ‘Cattle farmers and sheep
farmers should be watchful of animals that
are having difficulty lambing or calving.
Schmallenberg virus could be the cause.
‘But not necessarily in every case. Depressions
in milk production, or a drop in conception
rates could be due to other factors too - poor
forage quality being one possibility this
winter. Also, other diseases such as IBR can
have some of the same symptoms as
Schmallenberg virus.
‘We have also had an instance where a
sheep flock has suffered lamb losses which
were assumed to be due to the Schmallenberg
virus. But in fact, the farm had stopped
vaccinating for enzootic abortion a few years
ago and the disease had returned.
‘Toxoplasmosis could be another possible
cause of lamb abortions.
‘So if a lamb or lambs are born dead on the
farm it is worth having a postmortem carried
out to determine the cause of death. Defra
is currently covering the costs of this, and
once SBV has been confirmed on a farm,
no further testing is needed.’
Going forward
Charlie says: ‘It's too early to be able to
make assumptions that animals will develop
immunity to the virus. It's not clear yet whether
just because an animal has met the virus and
has raised antibodies to it, these antibodies
will be protective against further bouts of
disease or in fact, how long these antibodies
- and immunity - might last.
‘So for now, be vigilant, and discuss any
suspected cases of Schmallenberg virus with
your vet, who can help evaluate whether this
is the culprit behind abortions or a drop in
herd performance, or whether other factors
are the cause.’
For a copy of the XLVets Schmallenberg bulletin and for further
updates, visit
www.xlvets.co.uk
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