Are some goats resistant to scrapie? Information Sheet

Are some goats resistant to scrapie?
What’s the news?

How is scrapie usually transmitted?

Recent studies suggest that two goat prion gene
alleles can make goats resistant to classical scrapie.
This finding would offer goat producers a chance
to eliminate scrapie susceptibility from their goat
herds through selective breeding.

The classical form of the disease is naturally
transmitted from infected does during kidding via
ingestion of infected placenta or birthing fluids by
herd mates and newborn kids. Previous
contamination of premises is believed to be
another source of scrapie infection. Once infected,
the animal remains infected for life. Good
management and biosecurity practices are critical
in reducing the chance of infection in goat herds.

“Scrapie resistance genotype testing offers
goat breeders valuable tools for genetic selection
that sheep breeders have used for years
to promote scrapie eradication.”
—Dr. Joan Dean Rowe
Veterinarian and Dairy Goat Breeder

What is scrapie?
Scrapie is an infectious degenerative disease
affecting the central nervous system of sheep and
goats and is believed to always be fatal. Scrapie
results from infection with a disease-causing agent
known as a prion. Prions disrupt the normal
nervous system structure and ultimately lead to
formation of abnormal protein deposits in the
central nervous system, which in turn leads to
progressive neurological degeneration. Scrapie is
a transmissible spongiform encephalopathy (TSE),
which is a class of diseases that includes bovine
spongiform encephalopathy (BSE, or “mad cow”
disease) and chronic wasting disease of deer
and elk.

What are the important prion gene
alleles for resistance in goats?
The two alleles that appear to make goats resistant
to classical scrapie are S146 and K222. Goats that
have a single copy of either of these alleles have
been resistant to scrapie infection during natural
disease outbreaks and also direct challenge
experiments.
Both of these alleles occur naturally in U.S. goats.
So far, the S146 allele has been identified in both
dairy and meat goat breeds, including Alpine,
Nubian, Boer, Saanen, LaMancha, Pygmy, and
Tennessee fainting goats (myotonic).
The K222 allele has been found
most often in dairy breeds,
including Toggenburg,
LaMancha, Alpine, Saanen,
and Anglo-Nubian goats.

Photo courtesy of Jennifer Bice,
Redwood Hill Farm.

Should I genotype my goats?
Why should I breed my goats for the
S146 and K222 alleles?
Scrapie negatively affects animal health and
welfare, animal movement, and trade. Infected
flocks can experience significant production loss.
Breeders can use genotyping information to select
breeding stock to increase frequency of the
beneficial alleles within their herds. Breeding for
resistance could help control classical scrapie at
the herd and population levels.
“By genotyping their goats, producers could potentially
reduce the risk of infection in their herds,
develop options to conserve genetics and animals if a
herd were to become infected,
and add market value to their breeding stock.”
—Dr. Joan Dean Rowe
Veterinarian and Dairy Goat Breeder

As with sheep, general management and
biosecurity practices are very important in
reducing scrapie infection in goats, and goat
producers are encouraged to maintain overall herd
health, enhance productivity, and reduce
inbreeding by selecting goats superior for many
traits, not just scrapie resistance.

Where can I have the testing done?
Goat genetic testing services are available at
Veterinary Genetics Laboratory of UC-Davis
(https://www.vgl.ucdavis.edu/services/GoatScrapi
e.php).
Testing services are being developed at NeoGen
Genomics, Inc.
(http://genomics.neogen.com/en/research-anddevelopment-genomic-discovery#sheep-andgoat).
Special pricing for genotyping might be
available for members of certain goat
associations.

Does the United States have an
official program for genetic testing
in goats?
Scrapie-resistance alleles in goats have not been
formally recognized in the United States, so
genetic testing in goats is not considered official
testing for scrapie program purposes. As part of
the National Scrapie Eradication Program,
however, USDA is considering conducting a
genetic-based herd-cleanup pilot project in goats—
similar to the one conducted for sheep—focused
on the S146 and K222 goat alleles.
For more information, please visit
https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animaldisease-information/sheep-and-goat-health/national-scrapieeradication-program/ct_scrapie_disease_information

References
A New Tool: Genetic Scrapie Resistance in Goats. SN White and DA
Schneider. June 2018. https://www.aphis.usda.gov/
animal_health/animal_diseases/scrapie/downloads/whiteschneider-2018-goat-scrapie-resistance-dna-test.pdf
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