It is estimated that more than 90% of UK herds have had exposure
to bovine virus diarrhoea virus (BVDv). BVD causes reduced
fertility, poor production and increased susceptibility to other
infections especially in young calves.
In advertising literature, the Scottish Government quotes the
annual benefits after eradication of BVD in your herd are likely to
LFA specialist beef
LFA cattle & sheep
Lowland cattle & sheep
(LFA=Less Favoured Areas)
Major financial losses result where infection is introduced into
a group of susceptible breeding cattle resulting in poor
reproductive performance and the birth of calves with persistent
virus infection. While elimination of infection from the herd
is optimal, vaccination is highly effective and produces a
substantial cost benefits.
Young calf persistently infected with BVD (right)
compared to similarly-aged normal herd mate.
Strict biosecurity measures and a robust herd health plan are
essential to prevent introduction of BVDv into your herd; effective
biocontainment measures are essential on those farms with active
infection to reduce the costs of BVD and to, eventually, eradicate
BVDv from the herd.
The main transmission route is by direct contact with cattle
persistently infected with BVD virus. It needs only one
persistently infected animal to be introduced into a susceptible
herd to cause very significant financial losses.
Cattle exposed to BVD virus may show few clinical signs,
producing protective antibodies within three to four weeks. In some
situations, BVD virus infection may temporarily lower immunity to
other infectious diseases exacerbating these clinical infections
particularly in young calves.
BVD virus infection may temporarily lower immunity to other
infectious diseases such as
- Respiratory infections,
BVD virus infection during early pregnancy causes embryonic
death and return to oestrus, foetal death/abortion, mummification
of the foetus, birth defects of the nervous system and eyes,
weak/premature calves, and live persistently-infected calves.
BVD virus is most important when it infects susceptible
breeding cattle during early pregnancy causing foetal
death/abortion, and birth defects.
Infection of the foetus before 110/120 days of pregnancy results
in the birth of a live calf but persistently infected (animal
carries the virus for life). This is caused by failure of the
developing immune system of the foetus to function properly before
110 days. After birth these calves carry the virus for life
and act as a potent source of BVDv infection for in-contact
susceptible cattle. Virus infection (not necessarily before
110 days), may also lead to various defects of the developing
foetus' eyes and brain. These calves may be born blind and
lack co-ordination. These calves should be culled for welfare
reasons, as well as being a source of infection.
Poorly-thriven yearling persistently infected with
BVD virus (far left) compared to herd mates.
BVD virus during pregnancy may cause:
- Embryonic death and return to oestrus,
- Foetal death/abortion,
- Mummification of the foetus,
- Birth defects of the nervous system and eyes
- Weak/premature calves,
- Live persistently-infected calves
Birth defects of the nervous system. Note the
low head carriage and wide stance. This calf was also very
unsteady on its feet.
Birth defects of the nervous system. Note the
Virus infection after 150 days gestation usually has little
effect with live calves born at full term. Abortion can occur
following infection at any stage of pregnancy but this is not
Virus infection after 150 days gestation usually
has little effect with live calves born at full
BVD virus can be spread in semen of persistently infected bulls
or in bulls experiencing acute BVD with transient virus infection.
BVDv will lead to low pregnancy rate due to embryonic death or
later foetal death/abortion. Bulls are vigorously tested for
BVD before entering AI studs. Testing for BVDv is essential for all
purchased bulls prior to their use on farm.
BVD virus can be spread in semen of persistently
infected bulls or in bulls experiencing acute BVD with transient
Bulls are vigorously tested for BVD before entering
In older animals acute BVDv infection can reduce milk yield,
increase the risk of clinical mastitis and retained foetal
membranes, and increase somatic cell counts.
Mucosal disease occurs when persistently infected animals
(calves infected before 110 days of pregnancy see above) become
superinfected with cytopathic BVD virus. The cytopathic BVD
virus usually arises from changes in the BVD virus within the PI
animal. Mucosal disease is most commonly seen in 6 to 12
month-old calves, and is usually seen as sudden onset depression,
fever and anorexia, with excess salivation. Ulcers appear in
the mouth and on the muzzle. There are purulent discharges from the
eyes and nostrils. There is profuse diarrhoea with shreds of gut
mucosa/blood present during the terminal stages. There is
rapid weight loss followed by death within 5-10 days.
Acute BVD infection:
Paired blood samples 3-4 weeks apart to demonstrate rising
antibody levels to this virus.
PI calves may be clinically normal but commonly present as
chronic "ill thriven" or stunted calves due to their susceptibility
to bacterial infection such as pneumonia. Testing for virus will
identify PI calves. Two virus positive samples taken 3-4 weeks
apart will confirm persistent infection, but in the vast majority
of cases, particularly in ill-thriven calves one positive test is
enough. Virus testing can be done via the blood or, particularly in
calves < 12 weeks off age, skin (usually a plug of tissue from
the ear when tagging). Skin testing is useful in younger calves
because detection of the virus is not impaired by the presence of
antibodies from the colostrum which may be present in the
Poorly grown persistently-infected BVDv calf.
This calf has chronic pneumonia and ringworm
Acute BVD - treatment of any concurrent
infections if present.
Persistent infection - Such cattle have often
been treated several times for digestive and respiratory
infections. PI animals should be disposed of immediately as they
act as a source of BVD infection.
Chronic pneumonia secondary to persistent BVDv
infection (PI calf).
General principles of disease control
Biosecurity and biocontainment are terms describing programs for
infectious disease control.
Biosecurity - reduce/prevent the introduction
of new diseases onto an operation from outside sources
Biocontainment - reduce/prevent the movement of infectious
diseases on the farm once biosecurity has been breached
Biosecurity is the first measure to prevent
introduction of disease onto your farm; biocontainment measures may
limit the financial losses following introduction of disease onto
your farm after management errors have allowed disease to
Johne's disease, Bovine Virus Diarrhoea virus (BVDv),
salmonellosis, tuberculosis, Leptospirosis, Infectious Bovine
Rhinotracheitis (IBR) are some examples of infectious diseases that
can be introduced onto your cattle farm and severely affect the
financial viability of your beef or dairy cattle enterprise.
Biosecurity is the first measure to prevent introduction
- Johne's disease,
- Bovine Virus Diarrhoea virus (BVDv),
- Infectious Bovine Rhinotracheitis (IBR)
Key Principles of Biosecurity
- Keep a closed herd
- If buying in cattle - only purchase from BVDv accredited
- If buying in cattle from non BVDv accredited herds blood
test and isolate before introducing to herd
- Prevent contact with cattle on neighbouring farms - double
Key Principles of Biocontainment
which will lead to eradication
- Screen all animals
- Vaccination - all heifers and cows after screening
- Culling - all PI animals immediately
Double perimeter fence prevents direct contact with
Many herds have BVDv present within their cattle where
disease/losses are partly controlled by PI calves acting as
"natural vaccinators" of the herd. When most adult animals in the
herd are immune disease losses are not so obvious to the
farmer. However, this situation is not optimum as losses can
be catastrophic if naïve breeding females are introduced into the
Various BVD vaccines are available in the UK, requiring either a
single dose or two dose primary course. All must have the primary
course completed prior to first service, with a variable time
between doses and variable time from completion of the course to
bulling depending on the vaccine used (See product SPC's for details). All
require regular boosters to maintain immunity which should be given
in accordance with the SPC recommendations (recommendations vary
depending on the vaccine used). Animals should be healthy when
vaccinated to allow an appropriate immune response, but if all
breeding females are properly vaccinated this will help to control
the disease by preventing BVD infection of the developing foetus
during pregnancy and production of PI calves.
BVD eradication is possible following whole herd blood testing
and elimination of all PI carrier animals. If farmers go for
eradication then strict herd biosecurity measures must be
maintained to prevent re-introduction of virus infection as the
herd will soon become naïve and therefore fully susceptible to
Cattle with mucosal disease must be euthanased immediately upon
diagnosis. Calves born with eye and brain defects, due to
virus infection during their development, should also be
A state-sponsored BVD eradication scheme is progressing well in
Scotland and further information can be accessed at