Bovine Viral Diarrhoea (BVD)

Mount Vets

Prevalence of BVD*

Disease Dairy Beef

BVD 57% 66%

Leptospirosis 68% 51%

IBR 67% 65%

*From DairyCheck and BeefCheck 2009

Herds Testing Positive to Disease Exposure

Exposure to Herds tested on project

What is BVD?

● Stands for Bovine Viral Diarrhoea● Spread mainly in faeces and nasal and ocular secretions● Can cause a transient scour● Has various effects depending on age and situation● Naïve/unvaccinated pregnant animal

Lose the calf – EED, mummified calf or abortionNot lose the calf – mutated, Persistent Infector or vaccinated

● Young naïve/unvaccinated non-pregnant animalWeakens immune system preventing protection and recovery

from scours and pneumonias, etc.

0 1 2 3 4 5 6 7 8 9

Months of gestation

Earlyembryonicdeath

Foetal death andmummification

Foetal death and abortion

Pregnancy – No Live Calf Born

0 1 2 3 4 5 6 7 8 9

Months of gestation

Earlyembryonicdeath

Foetal death andmummification

Foetal death and abortion

Congenital defects

Sero-positive / vaccinated calf

Pregnancy – Calf Born Alive

Congenital Defects

● Classically cerebellar hypoplasiaAtaxia/ Incoordination

● AlsoHydrocephalusOcular lens cataractsMicro-ophthalmia

0 1 2 3 4 5 6 7 8 9

Months of gestation

Earlyembryonicdeath

Foetal death andmummification

Foetal death and abortion

PI (persistently infected)

Congenital defects

Sero-positive calf

Pregnancy – Calf Born Alive

The Persistent Infector animal

● A BVD virus “factory”Sees BVD virus as “self”One tube of PI bood diluted with

7000 litres of water is still infectious1000 times more infective than an

infected adult

● Often poor doersBut may appear normal

● The “Trojan Cow”Often route onto farm

The main source of c

ontinued

BVD infectio

n on the fa

rm

The Life of a PI

● Survival50% die by the age of 180% die by the time they are 2BUT some live to be up to 8 years old showing that it is possible

for them to enter the adult breeding herd

● A PI cow always gives birth to a PI calfMaintains virus in the herd

Number of herds with PI animals found

PI’s by farm type

Mucosal disease

● PI animal becomes ‘super-infected’ with BVD virus

● Virus destroys the whole gut surface● Severe ulceration, dehydration● Death after about 2 weeks● No treatment.● Domino effect on groups of

PI’s

BVD Infection Suppresses the Immune System

● Diseases which increase when BVD on farm:Calf scours - Rotavirus and Coronavirus Pneumonia - RSV, IBR and PastuerellaSalmonellaJohnesFoul in the Foot

● Control and Eradication schemesSignificant improvement in calf disease levels

Typical Picture of BVD in an Infected Herd

● Often not initially noticedEffects build up, like a dripping tap

● Visual effectsSporadic deathAbortions and congenital deformities

● Less obvious signsImmune disruption

Poor calf health – scour, pneumonia

Mastitis etc.

Poor fertility

Control of BVD within a Herd

Control Strategy for BVD

● Assess Herd BVD StatusBulk milk test in dairy herds or blood sampling in beef.

● Remove BVDv from herdIdentify and cull PIs through blood sampling

● Assess herd biosecurity and put in place extra measures if necessary

● Implement vaccination programme

Numbers of Pi’s on each project farm

Scenario No. 1 - Herd 31

● Naïve herd in November 2010 - -ve on Bulk milk sample

● Bought a freshly calved heifer which was a PI in December 2010 and put her straight into the milking herd

● Heifer died in April

● July 2011 persistent pneumonia in youngstock. Bloods taken to find causative agent. Bulk milk also taken.

● All positive for BVD antibodies therefore must have been in contact with a PI. Bulk milk now very high Ab reading.

● Herd BVD vaccination commenced

● 21 PI’s found to date but have stopped finding them as got to the point at which the vaccine started to protect the cows

Keeping Clear – Good Biosecurity

● Assess your riskBuying-in cattleNeighbours stockOn farm visitors

● Ideal situationClosed herdDouble fencingQuarantine and test

● Just how secure can you be?

Did you test the bull before you bought him?

Practical Vaccination Regimes why and when

● To prevent birth of PIsUse in an endemically infected herd while we identify

and cull PI’sNaïve herd to reduce impact if virus enters

● Vaccinate the whole breeding herd● Calves?● Ongoing

Annual boosting injectionsVaccination of heifers a minimum of 2 months prior to

breeding

Bovilis BVD

● DosingPrimary course 2 doses

4 weeks apart 2nd dose at least 4

weeks before 1st service

Annual booster

● It protects the foetusPrevent birth of PI’s

Two Initial Injections are important

4 weeks apart Annual booster

Please Read the Vaccine Instructions

● Keep refrigerated at all timesDo not freeze

● Follow directionsShake bottle well before use

● Good vaccination techniqueSterile injection equipment

● Do not keep open vialsUse within timescale on datasheet

● Use at the right time! For BVD before bull goes in with heifers (or cows)

Scenario No. 2 Incorrect Vaccination protocol - Herd 32

● Endemically infected herd● Full vaccination program in place. Different vaccine to that

we normally use. Choice was due to timing i.e. can serve 3 weeks after second dose.

● Heifers have received 1st service before 3 weeks after the 2 nd injection

● 13 PI’s found. 12 from heifers before vaccination complete● 1 PI from a few days after. Drug company contacted and

investigation started

Scenario 3 – Commencing a vaccination program without blood sampling for PI’s - Herd 13

● Small beef herd● Previous problems with BVD● Vaccinating for 5 years● Blood screen showed 4 PI’s● Has vaccination not worked?● One of PI’s an older suckler cow. Two of the PI’s her

offspring● 4th PI was a poor doing calf that had been given to the

farmer. So vaccination had worked but had been put into place with a PI already breeding in the herd

Thank you for your attention