The SFCP National Standards were developed by the Canadian Food Inspection Agency (CFIA), in collaboration with the sheep industry, as the basis for Canada’s on-farm, voluntary scrapie control program. It is intended to be a long-term, internationally recognized flock/herd scrapie control program for the sheep and goat industries. This program is unique as a CFIA approved disease control strategy. The CFIA only provides a guiding hand in ensuring that the program retains key requirements to meet international standards. The day-to-day management and verification is placed in the hands of industry. If shown to be effective, the SFCP may be used as a template for other industry-led TSE control programs.
Given the nature of scrapie (see ‘What is scrapie?’), infection in a flock/herd may go undetected for many years. As well, with no reliable live animal test for detecting the disease in individual animals, one-time testing and eradication not possible. Working with these restrictions, the SFCP is designed to gradually assess whether flocks/herds are currently infected and to minimize the risk of contracting scrapie in the future. Flocks/herds advance through the various levels of the program as the risk of scrapie infection decreases. Producers have the option of following one of three pathways under the program. In Pathway 1, the assessment of risk (level the flock/herd has achieved on the program) is determined by the number of years that the producer has followed program requirements and scrapie has not been detected. In this pathway, flocks/herds advance one level (E, D, C, B, A, certified) for every year that the requirements are met. In Pathways 2 & 3, other technologies, such as genotyping for resistance to scrapie, are used in combination with disease surveillance to reach certification in a fewer number of years.
Requirements for all pathways include:
There are many reasons for controlling scrapie in the sheep and goat industries, including improved animal welfare, marketing advantages for individual producers, and strengthening the overall image of the industries. However, if the costs of the program greatly outweigh the benefits for individual producers, there will be little uptake of this voluntary program. Therefore, the primary goal of the pilot project is to generate information by testing the program on 60 sheep flocks and 10 goat herds from across the country. Producers can then apply a cost/benefit analysis of using the SFCP for managing the risk of scrapie on their own farms. In addition to determining program costs, the pilot project will test the on-farm practicality of the National Standards as developed by CFIA. Standards will be reviewed annually (or as needed) with CFIA and a producer committee to ensure the program is as user friendly as possible while retaining CFIA approval.
Variations at three regions of the sheep prion gene (codons 136, 154, 171) are associated with how easily sheep exposed to scrapie will become infected. By genotype testing, it is possible to determine which animals are genetically resistant to scrapie and will pass that resistance on to their lambs. Through this project, sheep breeders are offered the opportunity to genotype registered sheep at a discounted rate. Targeting purebred animals will hopefully lead to an eventual increase in scrapie resistance of the entire national flock.
Although genotyping is used in scrapie control programs in many countries, this project is currently the most extensive testing program in the world. Because the Canadian project includes ewes as well as rams, producers are better able to use the information to develop breeding programs that consider quality and performance first and then look at scrapie resistance among those top performing animals. There is no requirement for producers testing with this project to cull animals of a particular genotype. It is important to note that animals with susceptible genotypes do not have scrapie; only a greater potential of contracting the disease if they are exposed. The desired outcome of the project is to maintain flock productivity while increasing the scrapie resistance of the flock. This may include selective mating of highly productive animals with a genetic susceptibility to contracting scrapie with those of a more resistant genotype (Please see the accompanying article ‘Tips for using genotype information to breed for scrapie resistance in sheep’).
The National Survey of Scrapie Genetics at a Glance: