Bovine Viral Diarrhoea


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  • 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
  • Bovine Viral Diarrhoea

    1. 1. Bovine Viral Diarrhoea (BVD) Mount Vets
    2. 2. Prevalence of BVD* Herds Testing Positive to Disease Exposure Disease Dairy Beef BVD 57% 66% Leptospirosis 68% 51% IBR 67% 65% *From DairyCheck and BeefCheck 2009
    3. 3. Exposure to Herds tested on project
    4. 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. 5. Pregnancy – No Live Calf BornEarly Foetal death andembryonic Foetal death and abortion mummificationdeath0 1 2 3 4 5 6 7 8 9 Months of gestation
    6. 6. Pregnancy – Calf Born Alive Sero-positive / vaccinated calf Congenital defectsEarly Foetal death andembryonic Foetal death and abortion mummificationdeath0 1 2 3 4 5 6 7 8 9 Months of gestation
    7. 7. Congenital Defects● Classically cerebellar hypoplasia Ataxia/ Incoordination● Also Hydrocephalus Ocular lens cataracts Micro-ophthalmia
    8. 8. Pregnancy – Calf Born Alive Sero-positive calf Congenital defects PI (persistently infected)Early Foetal death andembryonic Foetal death and abortion mummificationdeath0 1 2 3 4 5 6 7 8 9 Months of gestation
    9. 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. 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
    11. 11. Number of herds with PI animals found
    12. 12. PI’s by farm type
    13. 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. 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. 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
    16. 16. Control of BVD within a Herd
    17. 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
    18. 18. Numbers of Pi’s on each project farm
    19. 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. 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?
    21. 21. Did you test the bull before you bought him?
    22. 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. 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
    24. 24. Two Initial Injections are important 4 weeks apart Annual booster
    25. 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. 26. Scenario No. 2Incorrect 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. 27. Scenario 3 – Commencing a vaccination program withoutblood 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
    28. 28. Thank you for your attention