Agriculture_Markets
Andrew M. Cuomo, Governor | Richard A. Ball, Commissioner
 
 
New York Ram Project

New York Scrapie Eradication Program
for New York Sheep and Goat Producers


History of Scrapie

The disease known as scrapie has been recognized for more than 250 years. The unusual name was coined from sheep trying to relieve the intense itching which results in "scraping" off the wool. In 1947, scrapie was introduced into a Michigan flock through sheep imported from Britain. Scrapie has spread throughout the U.S. since that time.

The Cause

Scrapie is a member of a family of diseases known as transmissible spongiform encephalopathies (TSEs), which are caused by an infectious protein called prions. After prions are ingested, they enter the lymphatic system and travel to lymph nodes. After many months, the prions are found in the brain where they cause "holes" in the brain tissue giving it a sponge-like appearance. Other TSE-type diseases are Bovine Spongiform Encephalopathy (BSE) in cattle, Chronic Wasting Disease (CWD) in deer and elk, and Creutzfeldt-Jakob disease (CJD) in humans.

A Slow Developing Disease

Sheep (and goats) are infected at a very young age, but may not show symptoms of disease until two to six years of age. Goats are susceptible to scrapie when raised together with sheep but do not appear to spread the disease. Since scrapie affects the central nervous system, it can be confused with a number of other diseases, however it is always fatal. Symptoms develop slowly and may go unrecognized at first. Symptoms may include:

  • Weight loss despite normal appetite
  • Behavioral changes
  • Excessive itching and rubbing
  • Wool pulling or biting
  • Lip smacking
  • Loss of coordination
  • Startling at sudden noise or movement
  • High-stepping gait (front legs)
  • Bunny-hop movement (rear legs)
  • Tremors
  • Swaying of back-end
  • Down and unable to stand
  • Death
Scrapie Diagnosis

A positive diagnosis of scrapie in a flock is based on symptoms, duration of illness, and submission of brain tissues from an affected animal. The presence of prions in a microscopic section of brain tissue is the only method to be certain that sheep are infected with scrapie. A test of lymph tissue contained in the third eyelid of sheep can be performed by a regulatory veterinarian in some instances, but this test is not used for routine scrapie diagnosis. If you suspect that one of your sheep may be infected with scrapie, you should contact your local veterinarian for a diagnosis.

Scrapie and Genetics

Research has shown that certain genes in the DNA of sheep play a role in the development of scrapie. A simple DNA test on a blood sample can reveal the resistance or susceptibility of sheep to scrapie. Resistance or susceptibility can be determined by an approved laboratory by examining the DNA at Codon 171 of the genetic make-up. Letter designations are reported for each strand of the DNA. An "R" at Codon 171 indicates resistance to scrapie, whereas, a "Q" indicates susceptibility. Three combinations are possible since there are two strands of DNA:

RR = Highly resistant
QR = Moderate resistance
QQ = Susceptible

By knowing the genetics of breeding animals, producers will have the ability to breed more resistance to scrapie into their flock. Producers who retain their own replacement ewe lambs can begin influencing their flock resistance to scrapie by selecting rams that have been DNA tested and certified by an approved lab as carrying the "RR" gene at Codon 171. In the future, this new research will hopefully greatly increase a flock’s resistance to scrapie. There is no genetic test available for goats at this time.

Scrapie Eradication Program

USDA also offers assistance in the eradication of scrapie by utilizing genetics in a flock based clean-up plan by surveying cull ewes at slaughter. Infected ewes are traced back to their originating flock, which is DNA tested and susceptible sheep are removed.
USDA covers the costs associated with the clean-up of infected flocks including the DNA testing and indemnification for infected and susceptible sheep at fair market value. Other aspects of the eradication program include identification of sheep and goats with official USDA scrapie tags in:
  • Sheep and goats of any age being sold for breeding or as a pet
  • All sheep and goats being exhibited
  • All sheep and goats (wethers included) over 18 months old, in slaughter channels. This includes animals going to a livestock market or directly to a slaughter plant.
Producers must also keep good records including names and addresses of purchases and sales of sheep from the flock.

Voluntary Scrapie Flock Certification Program

USDA provides producers the opportunity to further protect sheep from scrapie and to enhance the marketability of animals through certifying scrapie-free flocks. The program monitors flocks over a period of five years or more to identify flocks that are free of scrapie.

Because there is no live animal test for this disease and scrapie has a long incubation period, a flock is considered free of disease if no sheep have been diagnosed with scrapie over a period of time.

The economic value of animals in enrolled flocks increases the longer they are in the program, especially once the flock is certified. Animals from certified flocks are a valuable source for replacement breeding animals, especially when the genetics of the replacements are known. A list of flocks enrolled in the certification program and their status is available on the USDA web site.

To participate in the program, flock owners must:
  • Report any scrapie suspects immediately to animal health official.
  • Officially identify all sheep over one year of age or when a change of ownership occurs (except slaughter).
  • Maintain adequate records including all sales, purchases, births and deaths for a minimum of five years.
  • Agree to an annual inspection by regulatory health officials for symptoms of scrapie, record completeness, and verifying identification of the flock.
  • Purchase replacement breeding animals from flocks of equal or higher status.
New York Efforts

DAI, in cooperation with USDA APHIS, has continually worked to eradicate scrapie by issuing sheep producers with official identification tags to use when selling animals from their flocks and educating producers and veterinarians on new information regarding scrapie and its eradication efforts.

Approved Laboratory for Genetic Testing

Biogenetic Services, Inc.
801 32nd Avenue
Brookings, SD 57006
www.biogeneticservices.com

More Information Available on the Web

United States Department of Agriculture Animal and Plant Health Inspection Service
USDA APHIS

New York State Department of Agriculture and Markets’ Division of Animal Industry
NYSDAM DAI