1. C S Parker BVM&S DBR MRCVS
Sheep Disease Schemes
C S Parker BVM&S DBR MRCVS

2. Schemes Available Scrapie Maedi Visna Enzootic Abortion
Future- Contagious lymphadenitis
Far future foot rot?

3. Scrapie What causes it What are the signs How is it transmitted
MAFF monitoring
Scrapie Genotyping

4. What causes Scrapie ? 3 theories prion genetics
Nobody knows. Possibly in excess of 20 different variations or serotypes
Is an infective agent involved
£ theories
Unusual small virus
prion- a malformed brain protein, This abnormal protein builds up in cells, brain is particularly effected
a virino, a small piece of DNa that acts as a virus
Whatever - very resistent to heat/UV/sterilisation etc
Transmissable in fluids etc, therefore infectious

5. Diagnosis Clinical Signs Post mortem
Disease has a long incubation years, therefore diagnosis prior to clinical signs developing can require sacrifice of stock
MAFF scrapie monitoring scmeme

6. DEFRA scrapie monitoring scheme
Voluntary certification scheme
Holding subject to Veterinary checks
animals identified
No case scrapie confirmed for 3 years
Proportion of cull ewes brain sampled
Restocked from similar premises

7. Clinical Signs Itching rubbing and nibbling
Intense pruritis, sheep rub against fixed objects
extensive wool loss + skin damage
Exstatic sheep
nibbling reflex

8. Clinical Signs Hyperexcitability general trembling odd expression
Sheep dash about
Head for dark corners etc

9. Clinical Signs
Inco-ordination

10. How is it transmitted At birth pasture contamination Other vectors?
Average age at death months
Most sheep infected since early life, infected at birth but not by milk P

11. Scrapie genotyping Only one test in animals life tested at any age
blood test
can be limited to stud rams
can be combined at VM testing
Known that sheep require combination of infective agent + right genetic make-up. If select sheep for correct genes - cannot be infected.
Advised that flockmaster tests 3 rams for every teo replacements required.
Ewes selected for embryo transfer should also be tested.
Not a test for the prescience of scrapie

12. How does it work 3 codons tested 136 154 & 171 Various combinations
Gene test available in 4 forms
Full genotyping all 3 significant codons tested - Cheviots, Scots blackface,
Lleyn, Swaledale texel etc.
Two codons test - Bleu de maine Border Leicester etc
! codon -171 cotswolds hampshire Down Soay etc

13. What does it cost? Full testing 1-19 £36 Two codons £30 Codon 171 -£13

14. Maedi Visna Chronic disease Maedi -chronic pneumonia
Visna nervous wasting disease

15. Clinical Signs
long incubation
progressive pneumonia
nervous form

16. transmission
milk/colostrum
respiration

17. Control Schemes
Monitoring scheme
Accreditation scheme

18. MV monitoring scheme commercial flocks Not strict isolation rules
Not MV accredited
Same test protocol as accreditation scheme
Only 1 entry test required

19. MV accreditation
Strict isolation- 2 metres for grazing, 7 days time lapse
May share buildings <10 days - 2m barrier
2 initial tests then bi-annual

20. Future schemes
EAE
Foot Rot