The following information was taken from the Canadian Food Inspection Agency and the United States Department of Agriculture’s websites.
It is important for producers to be able to recognize the signs of scrapie on their farm. As these can vary, producers must be aware of the different symptoms so they know what to look for and how to respond to the situation. According to the Canadian Food Inspection Agency (CFIA), scrapie is slow to develop, usually taking more than a year and a half for clinical signs to appear in an infected animal. In some cases however, it has been known to take up to eight years to develop, but typically, cases occur in animals between two and five years of age. Once an animal appears ill, it will die in one to two months.
The CFIA says that symptoms vary tremendously between cases of scrapie. One may observe an older animal with changes in general behaviour such as aggression or apprehension, tremors, incoordination or abnormal gaits. However, scrapie can also present itself as a mature poor-doing animal with a poor wool coat or even simply as a found dead.
The United States Department of Agriculture (USDA) agrees that signs of scrapie vary widely among individual animals and develop very slowly. They say that due to damage to nerve cells, affected animals usually show behavioral changes, tremor (especially of head and neck), rubbing, and locomotor incoordination that progresses to lying down and death.
The USDA sights early signs such as subtle changes in behavior or temperament. These changes may be followed by scratching and rubbing against fixed objects, apparently to relieve itching. Other signs are loss of coordination, weakness, weight loss despite retention of appetite, biting of feet and limbs, lip smacking, and gait abnormalities, including high–stepping of the forelegs, hopping like a rabbit, and swaying of the back end.
The USDA also says that an infected animal may appear normal if left undisturbed at rest. However, when stimulated by a sudden noise, excessive movement, or the stress of handling, the animal may tremble or fall down in a convulsive–like state.
According to the USDA, producers should be aware that several other problems can cause clinical signs similar to scrapie in sheep, including the diseases ovine progressive pneumonia, listeriosis, and rabies; the presence of external parasites (lice and mites); pregnancy toxemia; and toxins.
Scrapie can be present in both open and closed flocks and herds. It must be understood that just because a flock or herd has been closed for a number of years, does not mean that scrapie may not be present. It is important for producers to pay close attention to their animals and investigate any odd behaviour or sudden behavioural changes that may occur.
In Canada, scrapie is a reportable disease under the federal Health of Animals Act, and a control program exists to prevent its spread. As scrapie is a reportable disease, any suspect scrapie case must be reported to a CFIA veterinarian immediately. If, at any time, you suspect that scrapie may be on your farm, contact your local CFIA veterinarian. You can find your local Canadian Food Inspection Agency District Office on the CFIA web site at http://www.inspection.gc.ca/english/anima/heasan/offbure.shtml or by consulting the blue pages of your local phone directory.
Both the CFIA and the USDA offer further information about scrapie on their websites as well. The USDA’s website shows a number of videos related to scrapie, including clinical signs of scrapie and footage of an infected sheep. These videos can be found on the USDA website at: http://www.aphis.usda.gov/animal_health/animal_diseases/scrapie/
CFIA information can be found at: http://www.inspection.gc.ca/english/anima/disemala/scrtre/surve.shtml.
More information about scrapie can also be found by contacting Scrapie Canada at 1-866-534-1302 or by e-mail at admin@scrapiecanada.ca