Scrapie: Sheep’s Silent Killer

Scrapie Sheep's Silent Killer

As all sheep producers know, Scrapie can be a extremely costly and disruptive disease to your flock. Its high infection rate can decimate a flock of sheep in a matter of months. Within a matter of years, the infected flocks continue to spread the infection to non-infected sheep and can make the whole flock economically unviable. The presence of scrapie in the US has inhibited us from exporting a majority of our breeding materials along with meat and by-products to many other countries. Recently, there has been an increased focus on scrapie and the other transmissible spongiform encephalopathy diseases which has led the US to form a full-fledged program to eradicate these diseases in the US.

History of The Disease

Scrapie was first recognized as a disease in sheep in Great Britain and other western european countries more than 250 years ago. To date, only two countries are completely free of scrapie; Australia and New Zealand, both of which, are major sheep-producing countries. In the US, the first case was diagnosed in 1947, where a Michigan farmer had imported British sheep through Canada for several years. From that first case to today, there has been more than 1000 flocks diagnosed with the illness.

Some Breeds Are More Susceptible

Studies have shown, that certain breeds of sheep are more susceptible to scrapie than others. The studies found that Suffolk and Cheviot are the most susceptible, but, that doesn’t mean other breeds aren’t affected by this illness. Scrapie has been found in almost every breed including Cotswold, Dorset, Finnsheep, Hampshire, Merino, Montadale, along with several crossbreeds.

Clinical Signs

Unfortunately, there is no cure or treatment that your sheep can undergo for scrapie, however, if you catch the signs early enough, then you might be able to stymie it from spreading to the entire flock. Signs of scrapie vary widely among those it has infected, and signs can develop very slowly.

Early signs can include subtle changes in behavior or temperament of the infected. These subtle changes are usually followed by scratching or rubbing against fixed objects to alleviate the itching caused by the disease. Other signs could include loss of coordination, lip smacking, weight loss despite no loss in appetite, biting of feet and limbs, along with gait abnormalities.

Additionally, an infected animal may appear normal at rest, but if disturbed by a sudden noise, excessive movement, or stress from handling, the animal may fall down and appear to have convulsions.

Transmission

Scrapie is spread through fluid and tissue from the placentas of infected females. Which means that the disease can spread to an infected female’s offspring at birth as well as to other animals that are exposed to the same birth environment. Males can contract scrapie, but they cannot transmit the disease to other animals. A sheep’s genes affect both its susceptibility to the disease and the length of the incubation period.

What You Can Do

Sheep with certain genetic types are more resistant to scrapie than others. Blood tests can determine the genetic profile of a sheep. Producers that want to minimize the risk of scrapie in their flock can consider selective breeding for genetic resistance to this detrimental disease. However, even genetic resistant sheep can still be infected with scrapie.

Additionally, good food management and bio-security practices such as individual animal identification, record keeping, quarantining sick animals, clean birthing environments, and equipment disinfection practices can help reduce the environmental risks of infecting your livestock.

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