Scrapie - An Introduction
Scrapie is a fatal brain disease of sheep. Signs of scrapie should not be ignored, but should be tackled before it becomes a flock problem.
Scrapie develops due to changes in a protein present in the brain known as prion protein. Sheep affected by scrapie often display a general change in temperament or behaviour weeks before more specific signs develop. In most cases animals will show a combination of signs, but none of the signs alone can be regarded as a definite indication of scrapie. Scrapie should be considered in any sheep or goat showing nervous signs or changes in behaviour. Scrapie has been present in sheep for over 200 years and by law any animals suspected of having scrapie must be reported to the flock owner’s local Divisional Veterinary Office (DVO).
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.
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 of scrapie can occur over a short period of time, mostly in animals born around the same time and possibly to the same sire. Cases can occur at any time of year, but stress can cause the clinical signs to appear. Scrapie is 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.
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.
Clinical signs of scrapie -
Irritation
- repeated rubbing of flanks and hindquarters against objects such as fences, posts or hay racks
- repeated scratching of the flanks
- nibbling or grinding of 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
- excessive wool loss or damage to the skin
Changes in behaviour
- becoming excitable
- drooping ears
- increased nervousness or fear response
- lagging behind
- aggression
- depression or vacant stare
Changes in posture and movement
- trembling (mainly of the head)
- unusual high stepping trot in early stages
- severe lack of coordination
- stumbling
- standing awkwardly
- weak hind legs
- unable to stand
Later clinical signs
- weight loss
- death
If scrapie is suspected
Flock owners must immediately inform their local DVO. Signs of scrapie should not be ignored. If scrapie develops in a flock it will be difficult to get rid of as it spreads slowly and infection can remain in the environment for a long time.
Scrapie should be tackled before it becomes a flock problem.
For further information on scrapie please contact your local Divisional Veterinary Office.
