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

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

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

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

Diagnosis Clinical Signs Post mortem Disease has a long incubation 3 - 5 years, therefore diagnosis prior to clinical signs developing can require sacrifice of stock MAFF scrapie monitoring scmeme

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

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

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

Clinical Signs Inco-ordination

How is it transmitted At birth pasture contamination Other vectors? Average age at death 36 - 40 months Most sheep infected since early life, infected at birth but not by milk P

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

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

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

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

Clinical Signs long incubation progressive pneumonia nervous form

transmission milk/colostrum respiration

Control Schemes Monitoring scheme Accreditation scheme

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

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

Future schemes EAE Foot Rot