4. 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 abortion
Not lose the calf – mutated, Persistent Infector or vaccinated
● Young naïve/unvaccinated non-pregnant animal
Weakens immune system preventing protection and recovery
from scours and pneumonias, etc.
5. Pregnancy – No Live Calf Born
Early
Foetal death and
embryonic Foetal death and abortion
mummification
death
0 1 2 3 4 5 6 7 8 9
Months of gestation
6. Pregnancy – Calf Born Alive
Sero-positive / vaccinated calf
Congenital defects
Early
Foetal death and
embryonic Foetal death and abortion
mummification
death
0 1 2 3 4 5 6 7 8 9
Months of gestation
8. Pregnancy – Calf Born Alive
Sero-positive calf
Congenital defects
PI (persistently infected)
Early
Foetal death and
embryonic Foetal death and abortion
mummification
death
0 1 2 3 4 5 6 7 8 9
Months of gestation
9. The Persistent Infector animal
● A BVD virus “factory”
ed
nu
Sees BVD virus as “self”
One tube of PI bood diluted ti m
o n fa r
with 7000 litres of water is still
infectious fc e
o th
ce on
1000 times more infective than
an infected adult
ur n
so tio
● Often poor doers a in ec
m inf
he VD
But may appear normal
T B
● The “Trojan Cow”
Often route onto farm
10. The Life of a PI
● Survival
50% die by the age of 1
80% die by the time they are 2
BUT 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 calf
Maintains virus in the herd
13. 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
14. BVD Infection Suppresses the Immune System
● Diseases which increase when BVD on farm:
Calf scours - Rotavirus and Coronavirus
Pneumonia - RSV, IBR and Pastuerella
Salmonella
Johnes
Foul in the Foot
● Control and Eradication schemes
Significant improvement in calf disease levels
15. Typical Picture of BVD in an Infected Herd
● Often not initially noticed
Effects build up, like a dripping tap
● Visual effects
Sporadic death
Abortions and congenital deformities
● Less obvious signs
Immune disruption
Poor calf health – scour, pneumonia
Mastitis etc.
Poor fertility
17. Control Strategy for BVD
● Assess Herd BVD Status
Bulk milk test in dairy herds or blood sampling in beef.
● Remove BVDv from herd
Identify and cull PIs through blood sampling
● Assess herd biosecurity and put in place extra measures if necessary
● Implement vaccination programme
19. 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
20. Keeping Clear – Good Biosecurity
● Assess your risk
Buying-in cattle
Neighbours stock
On farm visitors
● Ideal situation
Closed herd
Double fencing
Quarantine and test
● Just how secure can you be?
22. Practical Vaccination Regimes
why and when
● To prevent birth of PIs
Use in an endemically infected herd while we identify
and cull PI’s
Naïve herd to reduce impact if virus enters
● Vaccinate the whole breeding herd
● Calves?
● Ongoing
Annual boosting injections
Vaccination of heifers a minimum of 2 months prior to
breeding
23. Bovilis BVD
● Dosing
Primary course 2 doses
4 weeks apart
2nd dose at least 4
weeks before 1st
service
Annual booster
● It protects the foetus
Prevent birth of PI’s
25. Please Read the Vaccine Instructions
● Keep refrigerated at all times
Do not freeze
● Follow directions
Shake bottle well before use
● Good vaccination technique
Sterile injection equipment
● Do not keep open vials
Use within timescale on datasheet
● Use at the right time!
For BVD before bull goes in with heifers (or cows)
26. 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
27. 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
Extra BVD project slides %age positive to exposure Overall number of herds with Pis Split into beef and dairy Numbers of Pis Numbers of Johnes positive 3 different on farm scenarios; Palfrey, Tucker and Jones
