Scrapie in Sheep: Welfare and Control of a Prion Disease

Scrapie is a fatal prion disease of sheep that causes progressive neurological deterioration and intense pruritus. Genetic selection for resistance and improved flock management can eliminate this welfare-significant disease.

Key Facts

Scrapie is a transmissible spongiform encephalopathy caused by misfolded prion proteins, related to BSE and CJD
The incubation period is typically 2 to 5 years, meaning animals appear healthy while incubating disease
Clinical signs include intense scratching against fences, wool loss, progressive incoordination, and wasting
The disease is invariably fatal — there is no treatment once clinical signs appear
Sheep carrying two copies of the ARR allele of the PRNP gene are highly resistant to classical scrapie
National scrapie plans in the UK and EU have used genetic selection to dramatically reduce prevalence
Atypical scrapie, caused by a different prion strain, occurs at lower frequency and in genetically resistant animals

Welfare Considerations

Sheep with scrapie experience months of progressive neurological deterioration characterised by intense, unrelenting pruritus that drives compulsive rubbing causing severe skin damage, exhaustion, and secondary infection. As the disease progresses, coordination fails and animals become unable to eat or drink normally. The welfare impact is significant and prolonged. Prevention through breeding for genetically resistant animals with the ARR/ARR genotype is the most effective long-term welfare intervention, effectively eliminating disease from flocks over successive generations.

What You Can Do

If you farm sheep, participate in the National Scrapie Plan or equivalent genetic improvement scheme
Select breeding rams with ARR/ARR PRNP genotype to build flock resistance over generations
Report suspected scrapie cases to your national veterinary authority — statutory notification is required in most countries
Support research into atypical scrapie which is not addressed by current genetic resistance programmes
Humanely euthanise clinically affected animals promptly rather than allowing prolonged decline