LAUSR

Simple Summary Blood has been considered a sterile environment. However, recent studies demonstrated the presence of bacterial DNA in healthy individuals. Most of the research has focused on human health, although this is an expanding topic in animal health. More needs to be done to understand the origin of bacteria found in blood, especially in relation to the host’s health status. This study aims to characterize the blood microbiome in healthy dogs and dogs with gastrointestinal disease and to compare the microbial blood population with the fecal microbiome. Results showed a clear separation of blood and fecal microbiome between the healthy and unhealthy groups, suggesting a translocation of the bacteria from the gut to the blood. More investigations are necessary to understand the bacteria’s origin and viability in blood. Abstract Recent studies have found bacterial DNA in the blood of healthy individuals. To date, most studies on the blood microbiome have focused on human health, but this topic is an expanding research area in animal health as well. This study aims to characterize the blood microbiome of both healthy dogs and those with chronic gastro-enteropathies. For this study, blood and fecal samples were collected from 18 healthy and 19 sick subjects, DNA was extracted through commercial kits, and the V3-V4 regions of the 16S rRNA gene were sequenced on the Illumina platform. The sequences were analyzed for taxonomic annotation and statistical analysis. Alpha and beta diversities of fecal microbiome were significantly different between the two groups of dogs. Principal coordinates analysis revealed that healthy and sick subjects were significantly clustered for both blood and fecal microbiome samples. Moreover, bacterial translocation from the gut to the bloodstream has been suggested because of found shared taxa. Further studies are needed to determine the origin of the blood microbiome and the bacteria viability. The characterization of a blood core microbiome in healthy dogs has potential for use as a diagnostic tool to monitor for the development of gastro-intestinal disease.