In Canada, scrapie is a reportable disease under the Health of Animals Act, and all suspected cases must be reported to the Canadian Food Inspection Agency (CFIA).
If a producer or their veterinarian suspects scrapie in any animal they are obliged to report it to the nearest CFIA office. If in doubt, phone the CFIA. The prevalence of scrapie is very low in Canada; reporting is key to finding the remaining scrapie infected animals.
How to recognize scrapie
Age
Scrapie is a disease that develops slowly. Clinical signs are only seen in adult animals, typically between two and five years of age. Once an animal shows signs of scrapie, it will typically die within a few months.
Number affected can vary
You can't always tell if an animal has been infected. Clinical signs of classical scrapie, when apparent, occur a long time after infection. The flock/herd may be infected, but only one animal may shows signs. Single cases can occur in a flock/herd. Multiple cases are more likely where animals are kept indoors.
Season
Scrapie cases can occur at any time of year, but stress can cause the clinical signs to appear. Cases are more easily identifiable at times when animals are collected for management purposes, such as lambing/kidding, weaning, or breeding.
Clinical signs of scrapie
Clinical signs vary tremendously between cases of scrapie, and there are no signs that are a definite indication of the disease. There is often a general change in temperament or behaviour in the weeks before more specific signs develop. In some cases, an affected animal's condition may worsen rapidly or it may be found dead. An adult animal may show changes in general behaviour such as aggression or apprehension, tremors, incoordination, or abnormal gait. However, a mature thin animal with a poor coat may also be diagnosed with the disease.
Animals with scrapie can show a combination of the following signs:
Changes in behaviour:
- become excitable
- have drooping ears
- show increased nervousness or fear
- lag behind
- apprehension
- aggression
- depression or have a vacant stare
- excessive licking
Skin irritation:
- repeated rubbing of the head and body against objects such as fences, posts, or haystacks;
- repeated scratching of the flanks. Horned animals may scratch with their horns;
- nibbling or grinding teeth when rubbing themselves or when rubbed firmly on the back;
- continued scratching of the shoulder or ear with a hind foot. Unusual or agitated nibbling of the feet, legs, or other parts of the body; and
- excessive wool or hair loss or damage to the skin.
Changes in posture and movement:
- trembling (mainly of the head)
- unusual high-stepping trot in early stages
- severe incoordination
- stumbling
- standing awkwardly
- weak hind leg
- unable to stand
Later clinical signs:
- weight loss, despite a good appetite
- death
The disease will eventually result in death of the animal.
Several other problems can cause scrapie-like signs in sheep and goats, including ovine progressive pneumonia, listeriosis, rabies, the presence of external parasites (lice and mites), pregnancy toxemia, and toxins.
If you observe a change in behaviour in your herd or flock, contact your veterinarian. If your veterinarian suspects scrapie on farm, they are obligated to report it to the CFIA.
What CFIA does when a scrapie suspect is reported
A CFIA veterinarian will examine the animal as soon as possible after a report is made. What happens next depends on what the CFIA veterinarian observes on their visit. Your animal:
- may not be considered a scrapie suspect and no further action will be taken.
- could be quarantined and placed under observation. If the affected animal is a sheep, it may be given a genetic test to determine its susceptibility to scrapie.
- could be ordered destroyed and tested for scrapie. If scrapie is confirmed, the CFIA will take disease control actions. Under the Health of Animals Act, the CFIA may compensate owners for animals ordered destroyed.
What happens when scrapie is confirmed
The CFIA takes disease control actions in response to an animal confirmed to have scrapie. While disease response situations can vary, the steps involved in a scrapie response normally include some or all of the following:
- initial investigation;
- quarantine;
- detailed investigation;
- destruction, disposal and associated compensation;
- cleaning and disinfection; and
- surveillance testing for five years.
For more information about scrapie disease control actions on farm, refer to What to expect if scrapie has been detected on your farm.