Scrapie Susceptibility and Genetics

Genetic testing, also referred to as DNA testing or genotyping, can determine a sheep's susceptibility to Scrapie. Scrapie resistance is determined by gene factors called codons. The most important codons relating to Scrapie resistance are the codons numbered 171 and 136.

A blood sample is all that is required to test for Scrapie susceptibility. It should be noted that genotyping only indicates an animal's susceptibility to Scrapie, not the presence or absence of the actual Scrapie disease agent.

In general, codon 171 yields "Q" or "R" factors and codon 136 yields "A" or "V" factors. It is desired to breed with rams that have at least one "R" factor. Selecting and retaining rams with "RR" in their genetic code will have the most impact on developing a Scrapie-resistant flock.

At this time, there are no approved official genetic tests for goats. The United States Department of Agriculture is currently conducting research in order to determine which codons affect Scrapie susceptibility in goats.