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.
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)
- Swaying of back-end
- Down and unable to stand
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 flocks 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
Producers must also keep good records including names and addresses
of purchases and sales of sheep from the flock.
- 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.
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:
New York Efforts
- 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
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
Approved Laboratory for Genetic Testing
Biogenetic Services, Inc.
801 32nd Avenue
Brookings, SD 57006
More Information Available on the Web
United States Department of Agriculture Animal and Plant Health
New York State Department of Agriculture and Markets Division
of Animal Industry