Scrapie is a prion disease that affects sheep and goats. It is a degenerative, fatal disease that affects the central nervous system (the brain and the spinal cord). Learn how to recognize the disease, protect flocks and herds, and what we're doing to keep Canadians safe.
On this page
- Forms of the disease
- The disease in Canada
- Reporting the disease
- Signs of the disease
- Transmission
- Diagnosis
- Treatment
- Protecting Canadian livestock from scrapie
- More information
Forms of the disease
There are 2 forms of scrapie, classical and atypical.
- Classical
- Classical scrapie has over 40 variants and can be transmitted from animal to animal, often spreading through excretions during birth.
- Atypical
- Atypical scrapie is rarer and occurs spontaneously, usually in older animals. It is not believed to spread between animals.
To date, there has been no known transmission of scrapie to humans.
The disease in Canada
Scrapie was detected in Canada for the first time in sheep in 1938, and has been detected routinely since then. Scrapie was made a reportable disease in Canada in 1945. A control program has been in place since then.
Scrapie is found in many countries all over the world.
Confirmed cases
Flocks infected with scrapie in Canada (2011 to present)
Reporting the disease
Scrapie is a reportable disease under the Health of Animals Act.
This means that, by law, all animals infected or suspected of being infected with scrapie must be reported to a Canadian Food Inspection Agency (CFIA) district veterinarian.
To report a suspected or known case of scrapie, contact your local CFIA animal health office.
How sheep and goat producers can help keep Canadians safe
- Contribute to scrapie surveillance
- Scrapie surveillance pamphlet
- Report a suspected or known case of scrapie: contact your local CFIA animal health office
Signs of the disease
Scrapie develops slowly. When present, clinical signs vary tremendously between cases of scrapie and are only seen in adult animals, typically between 2 and 5 years of age.
In some animals, the disease has taken up to 8 years to develop. However, once an animal appears ill, it will typically die within a few months.
An adult animal may show signs such as:
- changes in behaviour
- poor body condition / weight loss
- changes in posture or movement
- skin irritation
However, a mature animal with no obvious signs other than a poor coat, or one that is found dead, can also be diagnosed with the disease.
The disease seems to present itself differently in different countries. Wasting and debility (weakness) appear to be more prominent clinical features in North America, while pruritus (intense itching) remains the most noted clinical feature in Europe. Owners of scrapie-infected animals may be unaware that there is a problem with their flock or herd. Over time, especially in infected herds and flocks that contain a high percentage of susceptible sheep or goats, owners may experience significant production losses. Infected animals sold from these herds and flocks can spread the disease to other herds and flocks.
Transmission
Animals become infected with classical scrapie through exposure to other scrapie-infected animals and their scrapie-contaminated environment.
Scrapie is most commonly spread from an infected female to her offspring or other small ruminants (sheep and goats) exposed to the birth environment. Fluid and tissue from the placenta can contain large quantities of scrapie prions.
Healthy animals become infected by eating or licking any contaminated material in the birth environment. Genetically susceptible newborn lambs and kids have an increased risk of infection when born into a contaminated environment.
Animals incubating the disease without clinical signs can also be a source of infection to others. Prions in scrapie-infected sheep have been found in the milk, feces, saliva and urine of infected animals so transmission may also occur by these routes.
Exposure to an environment inhabited by scrapie-infected animals could put healthy animals at risk of contracting the disease.
Research shows that sheep with a particular genetic makeup are more at-risk of developing scrapie. Using genetic testing and selection, sheep producers can breed for resistance to scrapie.
Some genetic profiles that can offer resistance to developing scrapie in goats have also been identified, and are being explored for use in the National Scrapie Eradication Program (NSEP).
Diagnosis
Although animals infected with scrapie sometimes show signs, scrapie can only be confirmed by testing specific tissues from an infected animal after it is dead.
Biopsies of rectal lymphoid tissue or third eyelid lymphoid tissue from live sheep or goats can accurately identify some animals that have scrapie. These live animal biopsy tests can be useful for screening flocks or herds for the presence of infection but do not guarantee that the tested animal is free from the disease.
Treatment
No treatment or vaccine exists for the disease.
Protecting Canadian livestock from scrapie
At the CFIA, we have taken measures to prevent the introduction and spread of scrapie in Canada.
Learn about our National Scrapie Eradication Program.
Traceability
All Canadian sheep that leave their farm of origin are tagged with a radiofrequency identification device (RFID) to facilitate tracking activities should a disease issue occur.
Examining animals
Operators of abattoirs under federal inspection must, by law, evaluate each animal when it arrives at their facility in order to detect abnormal behaviour, physiology or appearance.
A CFIA inspector also inspects each animal to ensure that the ones showing potential signs of scrapie have been appropriately identified and segregated until a CFIA veterinarian can examine them.
If the animal is not slaughtered within 24 hours of this examination, a new examination and inspection must be performed.
This is an important step, as one cannot detect any visible abnormalities that are characteristic of scrapie in the carcass once the animal has been slaughtered.
What the operator is looking for:
- changes in behaviour
- changes in posture or movement
- poor body condition
If the CFIA veterinarian confirms that the animal presents signs, it will be condemned and will not be permitted to proceed to the slaughter floor or to other areas of the establishment where edible products are being processed. The animal will be isolated, humanely euthanized and then sampled for disease.
The carcass will be retained at the slaughterhouse until the results are received. If a test result returns positive, all parts of animal will be disposed of by federally approved prion destruction methods, such as burial, incineration or specified risk material (SRM) rendering.
In addition to testing animals that show potential signs of scrapie, we test a targeted number of sheep and goats over 12 months of age each year for scrapie surveillance after slaughter.
Good manufacturing practices and hygienic measures are routinely used to lower the risk of cross-contamination between products and from the environment.
Some measures in place include:
- daily sanitation of the slaughter environment
- ongoing sanitation and cleaning of tools and equipment
- control of product flow
- identification and segregation procedures