Goat genetics and scrapie
Genotyping sheep for susceptibility to scrapie infection is an internationally recognized tool in scrapie disease control programs in many countries, including Canada's National Scrapie Eradication Program (NSEP). More scientific information on goat genetics and scrapie susceptibility has become available both internationally and in Canada. The Canadian goat industry may now use genetics as a risk management tool for scrapie. Genotyping goats for susceptibility to scrapie infection will also be piloted as a disease control measure in the future, along with the other tools currently available in Canada's NSEP.
A genotype is an individual's collection of genes. Like all mammals, goats receive one allele for each gene from their dam (doe) and one allele from their sire (buck). Alleles are the different versions of a gene. Scrapie genotyping has been routinely used in sheep, and is now available to start using in goats. Genotype testing reveals the specific alleles inherited for the animals' prion gene that makes an animal more or less susceptible to scrapie.
Scrapie genotyping in goats
Results of a large amount of international and Canadian research on goat genotypes and susceptibility to scrapie are now available. Multiple variations in the goat prion gene have been studied and associated with different levels of scrapie resistance, depending on the breed of goat, the originating region of the animal and the individual study. Data from Canada, the United States and the European Union agree that goats having a single copy of either the S146 or K222 alleles have shown a strong degree of resistance to natural infection with scrapie.
These two alleles naturally occur in Canadian goat breeds, and can be used by the Canadian goat industry to routinely start genotyping in their breeding programs. These alleles will likely continue to be found in additional goat breeds in Canada as more goats are genotyped.
Producers who choose not to selectively breed for scrapie resistance are strongly urged to either close their herd or buy goats from herds in a scrapie flock certification program and start scrapie testing in mature deadstock.
How scrapie genotyping is used in the National Scrapie Eradication Program
It is important to understand that scrapie genotyping is not disease testing. Scrapie genotyping is used in the NSEP in sheep as a tool used by the CFIA during disease control actions with an infected sheep flock, to try to decrease the number of sheep ordered destroyed in the flock. At this stage, the CFIA will be preparing to pilot the use of genotyping in goats as an added tool during disease control actions, in eligible positive goat herds. The CFIA continues to contribute to and evaluate new science as it applies to goat scrapie, and when possible, will continue to transfer it to the NSEP.
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