Scrapie - Advisory Notes for Farmers (PB9446)

When does scrapie occur?

Age

Most cases of scrapie occur in sheep between two and five years of age. Although rarely seen in sheep less than one year of age or over five years old, age alone cannot be used to rule out the presence of scrapie. It is rarely reported in goats in the UK but, again, the possibility of the disease cannot be ruled out.

Numbers affected

Because clinical signs of disease appear a long time after initial infection, cases generally appear singly in a flock. This is very different from diseases such as sheep scab (psoroptic mange), which can spread quickly through a flock. Occasionally, several cases can occur over a short period of time, mostly in animals born at about the same time and possibly to the same sire.

Season

Cases can occur at any time of year, but stress can cause the clinical signs to appear. Cases are often more easily identified at times when sheep and goats are collected for management purposes, such as when sheep are brought in for lambing, or in the autumn, at tupping.

Development of clinical signs

Most sheep show a gradual development of clinical signs over a period of several weeks or even months, although in some cases an animal’s condition may worsen rapidly. Some sheep and goats affected with scrapie may just be found dead without showing any clinical signs beforehand.

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