Understanding

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					a producer ’ s guide to bvdv   –   also known as bovine pestivirus




Understanding
What is BVDV?                                                                                                             BVDV affects profitability in the feedlot
Bovine Viral Diarrhoea Virus (BVDV),                          For spread to occur, a susceptible animal can be            Bovine Respiratory Disease (BRD)
also known as Bovine Pestivirus, is an                        infected from direct contact with a PI animal or from       Complex has been frequently
                                                                                                                                                                                    BVDV infection suppresses the
infection of cattle well recognised as                        contact with infected discharges. The presence and          associated with BVDV.7,8
                                                                                                                                                                                    immune system, which may give
a significant disease in feedlots and                         movements of PI animals in a herd are the keys to the       •	 Direct contact of previously unexposed cattle with     rise to secondary infections:
both beef and dairy herds in Australia.                       spread of BVDV. Infection rates in a herd will depend          a PI animal can have a devastating effect on herd
The acronym BVDV can be misleading as this                    on the number of PI animals present, the level of herd         health and productivity.9
virus causes a variety of clinical entities, the most         immunity and the degree of contact between animals.
significant of which is reproductive disease. Originally      Management practices that result in close contact           •	 In high-stocking situations such as transportation,      • Bovine Respiratory Disease (BRD)
linked to diarrhoea and mucosal disease, BVDV has             (e.g. mustering, yarding or trucking) can accelerate           feedlots and yarding, viral transmission can take
                                                              transmission in a mob.                                         as little as 1 hour.10,11                                  complex
existed in Australia for over 40 years.
Recent serology testing in Australia indicates that
                                                              Persistently infected animals                               •	 Once infected with BVDV, cattle then become              • Mastitis
30-40% of all cattle and 80-90% of herds have some
                                                              Persistently infected (PI) animals are the principal way       susceptible to a wide range of secondary infections
evidence of past exposure to BVDV infection.
                                                              BVDV is spread and maintained within a herd.                   with other viruses and bacteria. This is because         • Pneumonia
How is BVDV transmitted?                                      The majority of PI animals can be recognised by                infection with BVDV suppresses the immune
                                                              vets and producers as ‘poor doers’, or sick animals that       system, making cattle much more likely to catch
Persistently infected (PI) animals are the principal way
                                                                                                                             other infections. These secondary infections are
                                                                                                                                                                                      • Footrot
BVDV is spread and maintained within a herd.                  die before 18 months of age from mucosal disease,
                                                              or other diseases associated with BVDV e.g. Bovine             from bacteria e.g. escherichia coli and viruses e.g.
When the foetus is infected between about 30–125                                                                             rotavirus already present in the herd, and can show      • Diarrhoea
                                                              Respiratory Disease (BRD) complex.
days of gestation and survives the infection to term,                                                                        as a broad range of symptoms from mastitis, calf
the developing immune system recognises the virus as          PI animals are often ‘immunological cripples’,
                                                              developing severe, non-responsive manifestations
                                                                                                                             scours and footrot to diarrhoea and pneumonia.           • Bovine papular stomatitis
‘self’. As a result, the foetus will be infected with the
virus for life (‘persistently infected’ or PI) and does not   of common diseases such as ringworm and
                                                                                                                          •	 Secondary infection is particularly serious in
produce antibodies to the virus. This leads to the birth      dermatophilus infection.
                                                                                                                             the feedlot situation, where a range of viruses,
of a seronegative calf that is immunotolerant to BVDV.        It is estimated that about half of all PI cattle succumb       mycoplasmas and bacteria can act in concert with
Persistently infected (PI) animals excrete large              to death within the first 12 months of life, and another       BVDV to cause Bovine Respiratory Disease (BRD)
amounts of virus in body fluids and discharges (nasal         half or more of the remaining PI animals die in the next       complex or ‘Shipping Fever’9, which results in
and oral secretions, eg saliva, aerosols, tears, milk,        12 months.                                                     complicated pneumonia and polyarthritis. These all
semen, urine and faeces) throughout their life, and           However, some PI animals appear ‘normal’, survive              result in high morbidity and mortality.
are the main reservoir of BVDV in a herd. The virus           longer than 18 months, and act as long-term carriers
can survive in these discharges in the environment for        of BVDV or ‘hidden transmitters’, continuing to infect      •	 A study in the U.S. by Hessman found that
short periods, perhaps a few hours to days depending          animals in the herd that have not yet been exposed to          exposure to PI in feedlot pen cost US$67.49
on exposure to sunlight, moisture levels and                  the virus. These animals do not show obvious signs of          per feeder 12
environmental temperature. Hot dry conditions rapidly         illness and are difficult to recognise and diagnose. They
inactivate the virus.                                         can breed successfully but their progeny are always PI.

                                                                                                                                                                                                       havuherd
The effect of BVDV on reproduction                                                                             Danger signs indicating possible BVDV infection
Reproduction                                                                                                   Reduced reproductive performance                                calves that are very small, don’t grow properly and
•	 Many of the clinical effects and reproductive losses due to BVDV infection occur                            •	 An increase in the number of heifers and cows                suffer other illnesses such as calf scours or pneumonia
   when heifers or cows are exposed to the virus during pregnancy,                                                returning to service after initial AI or joining          Reduced weaner/yearling growth and health
•	 Exposure to the virus around the time of joining or insemination may also reduce                            •	 Heifers and cows pregnancy testing in calf but failing    •	 ill thrift and deaths in weaners and yearlings
   conception rates. When the dam is infected during pregnancy, the virus can cross                               to deliver calves at full term
   the placenta and infect the developing foetus.                                                                 – Evidence of abortion or failure to calve                Increased incidence of infectious respiratory
                                                                                                                                                                            or intestinal disease
•	 Depending on the stage of pregnancy, this infection of the foetus may result                                •	 Spread out calving pattern
                                                                                                                                                                            •	 unexpectedly high incidence of disease such as
   in early foetal loss (presenting as return to service), abortion or stillbirth.
                                                                                                               Increased calf morbidity and mortality                          bovine respiratory disease or calf scours
•	 If the developing foetus survives to the end of pregnancy, the calf may be born
   with severe birth defects, die soon after birth or may be ‘persistently infected’                           •	 Stillborn or premature calves that die soon after birth   Mucosal disease
   with the virus.                                                                                             •	 Abnormal calves – weak, unable to suckle, blind or        •	 Clinical diagnosis of cattle suffering from Mucosal Disease
                                                                                                                  with neurological problems (ie. can’t stand or stand
                                                                                                                  abnormally, wobbly gait, incoordination, tremoring),
                                                                                                                                                                            Post mortem results
                                                                                                                  calves with contracted joints, abnormal hair loss or      •	 Evidence of changes consistent with BVDV infection
Stage when infected

         Around time of mating/AI                                              First trimester                                Second trimester                                                 Third trimester
   •		Disrupts ovulation and fertilisation                   •		Production of PI calves                        •		Abortions                                                         N
                                                                                                                                                                                 •			 o reported problems associated with
   •		Early embryonic death                                  •		Late embryonic death, abortions, stillbirths   •		Late delivery of unviable or abnormal calves                      infection during this period
                                                                                                                  at full term
                                                                                                               •		Central nervous system effects
                                                                                                               •		Eye defects
   • Reduces conception and pregnancy rates
   • Increases returns to service                                                                                 R
                                                                                                               •			 eduction in number of calves born and
   • Delays conception date                                                                                       viability of calves




                                                                    Aborted foetus

      Normal foetus (top)
                                                                                                                               BVDV infected brain
      Non viable BVDV infected foetus (below)
The economic impact of BVDV                                                                                            Effective control measures for BVDV may require the utilisation of several options.
                                                                                                                       1. Do nothing and accept losses                                      M
                                                                                                                                                                                        •				 inimise over the fence contact between
                                                                                                                                                                                            breeding females and neighbouring cattle
Precise costs of BVDV are difficult                         Economic modelling indicates                               2. Utilise autovaccination - using natural
to estimate, however, it has been found                     •	 The cost of an outbreak in a 250 head naïve                transmission of infection by deliberate mixing of                 V
                                                                                                                                                                                        •				 accinate cattle that are being transported off
that production losses between 25–50%                          (uninfected) herd is approximately $130,000                known PI cattle with breeding females well before                 the property and later returned
can occur in recently infected herds.1–5                       (gross dollars) and will take 13 years to recover.         mating.
                                                                                                                                                                                     4. Detection and elimination of PI cattle (utilising
With BVDV causing reduced conception rates,                 •	 The economic benefit of vaccination with                   It is critical the auto vaccinator cattle are tested and      antigen or virus detection eg ear notching)
abortions and poor calving rates, the majority of the          Pestigard in endemically (infected) beef herds             confirmed to be PI animals.
                                                                                                                                                                                        For maximum benefit, PI animals need to be
economic impact of BVDV is expressed as a lack of              varies from breakeven through to a benefit of
                                                                                                                          These animals must be clearly identified so that they         removed prior to the subsequent joining period.
surplus steers and heifers.                                    $34 per breeder per year.13
                                                                                                                          are not inadvertently mixed with cattle in the early
                                                                                                                                                                                        Several rounds of testing may need to be done
                                                                                                                          stages of pregnancy.
                                                                                                                                                                                        to remove all PIs.
Control options for BVDV for                                                                                              The PI auto vaccinator cattle should be placed in a
                                                                                                                                                                                     5. Adopt a herd vaccination program with
                                                                                                                          small yard with the replacement heifers each year at
best herd management practices                                                                                            least 16 weeks prior to the start of mating.
                                                                                                                                                                                        appropriate use of a vaccine capable of
                                                                                                                                                                                        inducing immunity sufficient to reduce PIs
                                                                                                                          Heifers should be tested before mating to ensure
                                                                                                                                                                                        Once the status of herd infection is determined,
Before considering the options available to control or prevent BVDV infection                                             they have had exposure to BVDV and have
                                                                                                                                                                                        a vaccination program can be developed to cover
the following should be done.                                                                                             developed immunity.
                                                                                                                                                                                        the most susceptible cattle at the highest risk
Work with your veterinarian to determine                                                                                  As PI cattle have a significantly shorter life                of exposure.
                                                                                                                          expectancy than normal cattle, they may die out,
1. The BVDV status of the herd or breeding group                   introduced or there has been contact with                                                                            Properly conducted, vaccination of a herd/
                                                                                                                          leaving the herd susceptible to infection over time.
   •			The status of the herd can be cost effectively              other cattle then re-sampling to define the herd                                                                     management group will result in a high proportion
        determined by serology using the BVDV guidelines.          BVDV status is recommended.                         3. Adopt management practices and biosecurity                    of females being immune to infection - which will
                                                                                                                          to minimize the risk of introduction of BVDV                  decrease losses due to exposure to BVDV.
   •			Only once the status of the herd is determined,         •			Testing to identify and remove PI animals
       can an appropriate control program, which may               can be incorporated and is recommended for             •			Establish a closed herd and use only semen and            Vaccination must be maintained to ensure long-term
       involve vaccination be devised.                             all seed stock producers - identified utilising            embryos from confirmed BVDV free donors                   protection. If ceased, over time the herd is likely
                                                                   detection of BVDV antigen in blood or tissue                                                                         to become susceptible to exposure to BVDV.
2. The risk of introduction / re-infection of the herd                                                                        T
                                                                                                                          •				 est all introduced cattle to confirm they are
                                                                   samples testing.
                                                                                                                              not PIs                                                   For further information consult bvdvaustralia.com
3. The cost benefit of BVDV control for the
                                                               •			Prior to all embryo transfer and artificial
   specific herd and management system                                                                                        Q
                                                                                                                          •				 uarantine all introduced cattle until test results
                                                                   insemination programs, all donors and recipients.
                                                                                                                              are known
4. Review the level of herd security and                           should be tested to determine their BVDV
   quarantine procedures for purchased animals                     status to ensure BVDV will not impact on                   D
                                                                                                                          •				 o not introduce pregnant females - there are
   •			Control programs should be reviewed before                  the success of the programs. All should be                 no tests available to determine whether or not
       each mating season and if cattle have been                  PI-negative and vaccinated.                                they are carrying a PI calf



                                                                                                                                                                                                                   havuherd
BVDV causes Reproductive and
Productivity losses
•    BVDV causes productivity losses in cattle herd production
•    BVDV causes reproductive losses
•    BVDV causes immunosuppression
•    BVDV is associated with Bovine Respiratory Disease (BRD) complex

Active immunisation with Pestigard is an effective and
                                                                                               ®



economical solution to controlling BVDV
                                                                                                       1st Season or
                                      Heifers                          Cows*                                                                    Bulls*
                                                                                                         New Bulls
      Schedule                    Primary Course                   Annual Booster                        Primary Course                     Annual Booster

        Timing               1st Dose:       2nd Dose:                                              1st Dose:        2nd Dose:
                            6-8 weeks        2-4 weeks                 2-4 weeks                   6-8 weeks         2-4 weeks                 2-4 weeks
                            pre-joining      pre-joining               pre-joining                 pre-joining       pre-joining               pre-joining


        Farm                      1st Dose may
                                                              May be given at pregnancy
                                                                                                         1st Dose may                       1st Dose may
                                                                testing or branding.
    Management                    be given up to
                                                               Pregnant cows can be
                                                                                                         be given up to                     be given up to
     Flexibility               6-months pre-joining                                                   6-months pre-joining               6-months pre-joining
                                                                     vaccinated†

     Pestigard ®               3                 3                        3                          3                  3                         3
• Protective immunity is expected to develop within 14 days of the second dose.
* Previously unvaccinated cows and bulls will require a primary course of vaccination consisting of two doses of vaccine,
  with an interval of 4-6 weeks between doses. The primary course of vaccination should preferably be completed 2-4
  weeks prior to joining/insemination.
† If a cow is pregnant with PI calf, vaccination will have no effect on the status of the PI calf.


                                                                                                                         ®




Can be used for 30 days after opening
For further information on a Pestigard vaccination program contact your Pfizer Professional Sales Representative. Pfizer Australia Pty Ltd,
38–42 Wharf Road, West Ryde NSW 2114. Freecall: 1800 335 374. ®Registered trademark of Pfizer Australia. References: 1. Meyling A et al.
Rev Sci Tech Off Int Epiz 1990;9:75–93. 2. Taylor LF et al. Can Vet J 1997;38:29–37. 3. Lee SC et al. Can Vet J 1994;35:641–642. 4. Taylor LF et al. Can Vet J
1994;35:425–432. 5. Taylor LF et al. Can Vet J 1997;38:23–28. 6. McGowan MR and Kirkland PD. Proceedings from Australian Association of Cattle Veterinarians
Annual Conference 1992:129-131. 7. Dunn SE et al. Final Report to Meat Research Corporation. Project 1994 DAN 064:1–79. 8. Kirkland PD and Walker KH. Perth
Conference Proceedings 2000:120–121. 9. Loneragan GH et al. JAVMA 2005;226(4):595–601.10. Larson RL et al. The Bovine Practitioner 2004;38(1):93-102.
11. Traven M et al. J Vet Med 1991;38:453-462. 12 Hessman B, Effects of bovine viral diarrhea virus (BVDV) persistently infected (PI) calves in the feedyard
and management of PI calves after initial identification. Oral presentation by the author at the BVDV Control; The Future is Now conference, Denver,
Colorado, USA, 2006 January 31. 13. The Impact of Bovine Virus Diarrhoea Virus (BVDV) on the Reproductive Performance of Beef and Dairy
Herds - Update on Autralian Research. M. R. McGowan and P.D Kirkland, The University of Queensland, School of Veterinary Science, St
Lucia 4072, Brisbane, Queensland 4072, Australia and Elizabeth Macarthur Agricultural Institute, PMB 8 Camden, NSW 2570,
Australia. Presented by author at the 2008 Australian Veterinary Association conference, Perth, May 27th 2008
AM02545 OGILVY HEALTHWORLD PAPE0090

				
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