BVDv: What is it and where does it come from? Rebecca Cavill BVetMed MRCVS CertAVP (Cattle) PgCert Photos from Nadis website

BVDv: What is it? It is caused by a pestivirus It is a virus that causes bovine diarrhoea (alongside other clinical signs) It is estimated that 90% of herds in the UK have had exposure to BVD (NADIS) It can survive in the environment for up to 7days It can be eradicated and there are eradication programmes in Scotland and the EU (Norway, Sweden, Finland and Denmark are almost free) It is shed by persistently infected animals (Pis)

How does it spread? BVD can be spread from animal to animal as easily as the common cold The virus does not persist well in the environment and is most commonly spread by PIs, however, it can be brought in on equipment and clothes or by transiently infected animals Once animals come across the virus there are two possible results of infection: Transient infection Persistent infection If after birth then transient infection as they have an immune system which can detect and clear the virus usually over a three week period. Persistent infection occurs when in utero. If a cow is between 1- 4months when she comes across the virus she will clear it and become immune but her foetus’s immune system is not fully developed and so does not recognise the virus as foreign, instead incorporating it as part of itself. This means that PI’s create large amounts of virus which are present in all their tissues and secretions including tears, saliva, faeces and urine.

What does it cause? BVD causes immunosuppression and this can be present as calves with pneumonia, scour, ringworm or poor growth rates. In adult cattle you may see scour, infertility, early embryonic loss (slipping of calving season), abortion, stunted or deformed calves, birth of dead calves PI animals can look completely normal or they stick out as poor-doers (the animal you keep back in each group). They can also develop mucosal disease which leads to ulcers in the mouth, gut and feet. Mucosal disease is fatal Blind calves, dummy calves

Case study: Dairy herd which rears bull calves on a rose veal contract Target is 145kg at 8months Bonus of 30p/kg over 145kg and 20p/kg between 125-144kg Vaccinating for BVD Vaccinates calves with Rispoval 4 (includes BVD) Buys in calves from tb restricted farm to rear for bull beef contract In November 2016 increased incidence of pneumonia despite vaccination 38 cases over two months (compared to 6 in previous two months) Respiratory screen which identified a PI Previously averaging 160.77kg at 8months with 6/41 not reaching 145kg (none not reaching 125kg) Two further groups slaughtered, pi held back so first group averaged 155.18kg with 5/19 not reaching 145kg (and one of these not reaching 125kg) and second group averaging 144kg with 9/15 not reaching 145kg (2 of these under 125kg) Mortality in previous 12months 3/120; in this 13months now 6/130 and 2 likely to be culled due to chronic pneumonia & several poor-doers

How to keep it out: Buying in: Know your sources Know their status Quarantine Don’t forget the bull!!! Test the dam AND the calf Vaccinate Bought-in calves access to early pregnant cows Bringing in Equipment People Boundaries Nose-to-nose contact Cull PIs

Any questions?