Scrapie is a terminal, degenerative disease that affects the central nervous system of sheep and goats. Scrapie belongs to the transmissible spongiform encephalopathies family of diseases. The exact cause of scrapie is unknown, but it is believed to be associated with an abnormal protein known as prion.
The name scrapie is derived from the clinical signs of the condition where the affected sheep and goats scrape off the fleeces against trees and rocks. Scrapies is spread through urine among sheep and goats. Scrapies mostly affects sheep and goats that are around 3 to 5 years of age.
Since scrapies develops slowly, the signs and symptoms are seen when the animals have grown to adulthood that is 3 to 5 years but in some cases it is noticed at 8 years of age. The following are the main symptoms of scrapies.
Older animals portray change in behavior such as abnormal gaits, apprehension, tremors and uncoordination. Other symptoms include:
- General weakness of the affected animal.
- Intense itching and rubbing on fences and trees.
- Shedding of goat and sheep hair due to itching.
- Lip smacking and moving in uneven manner.
- Convulsions and unexplained falling.
- Loss of weight.
- Wool pulling.
- Swaying of hips and hind limbs.
- Biting at limbs or side.
- Sensitivity to movement and noise.
The infected animal can succumb to scrapies after you to two months after the symptoms start showing.
The main mode of scrapies transmission is through placenta fluids and tissues of an infected female to her offspring at birth. Other animals that are exposed to the birth environment are at risk of contacting scrapies through the placenta fluids.
Cases of natural transmission have bee reported where a scrapies free sheep is infected through the alimentary tract after grazing on pastures where scrapies out break has been reported. Male sheep and goats contract the disease but do not transmit is to other animals. Sheep with a particular genetic makeup are at risk of developing srapies. The genetic makeup of sheep also determine the propensity and incubation period of scrapies.
Scrapies is diagnosed by conducting a biopsy of the peripheral lymphoid tissues of the sheep. However, this is not an accurate way to determine if a sheep has scrapies because the results may be negative and the particular sheep may be suffering form the disease. Scrapies is accurately diagnosed after death of an infected animal by examining the animals brain tissue, tonsils, spleen or the lymph nodes.
There is no treatment or vaccine available for scrapie disease. So the only way to ensure minimal loss is experienced due to scrapies out break is to take preventive measures that will help in minimizing the risk of scrapies in sheep. Some of these preventive measures include:
- Doing blood test to sheep so as to determine their genetic makeup.
- Doing selective breeding for scrapies genetic resistance sheep.
- Conducting scrapies test to the female sheep often.
- Isolation of the infected animal from other animals.
- Separation of female sheep from other animal during birth.
- Disinfection of equipments used between animals.
- Animal identification and record keeping.
A scrapies outbreak is the worst thing that can happen to a flock owner. So each stock owner should know how to respond to a scrapies out break. The following are tips and guidelines of the best way to respond to a scrapies out break.
- Destroy all infected animals
- Do a strict surveillance and trace potential and high risk animals
- In case you live in an area where there is scrapies outbreak, limit and control your sheep movement
- Disinfect and decontaminate the infected areas
- Conduct zoning to identify infected and free areas
- Since scrapies is a deadly disease, flock and farm owners should take all the necessary precautions to avoid scrapies out break n their farms and subsequent loss of animals.
- Purchase animals for certified scrapies free areas is very advisable.
- Prevent overcrowding and underfeeding of animals as this triggers the symptoms of scrapies.
- Avoid keeping sheep and goats in areas where scrapies has been reported as prion can live in the environment for years.
Sources and Citations
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