Scientific Opinion on Risk of transmission of TSEs via semen and embryo transfer in small ruminants (sheep and goats)
An assessment of the risk of transmission of Transmissible Spongiform Encephalopathies (TSEs) via semen and embryo transfer in small ruminants (sheep and goats) was performed. The TSE agents considered were Classical scrapie, Atypical scrapie and Bovine Spongiform Encephalopathy (BSE). Because of the lack of specific data for goats the assessment was carried out mainly using data obtained in sheep and, because of the similarities of TSE pathogenesis between sheep and goats, the assessment was also considered to be valid in goats. According to the data currently available, the risk of TSE transmission associated with semen and embryos collected from Classical Scrapie incubating sheep and goats ranges from negligible to low but the data are insufficient to conclude that such a risk is negligible. Because of the similarities between Classical scrapie and BSE pathogenesis in small ruminants, this statement is also to be considered valid for BSE. The lack of knowledge of the pathogenesis and anatomical distribution of the Atypical scrapie agent within affected animals hampers the possibility to provide an assessment of its transmission risk via semen or embryos. Due to the use of animal-derived hormones and surgical devices for artificial insemination and embryo transfer procedures there is an inherent but unquantifiable risk of iatrogenic TSE transmission associated with these practices.