The Vaginal Microbiome of Mares on the Post-Foaling Day Under Field Conditions.

The vaginal bacteria are critical for neonatal immunity, as well as for further infections and pathologies in foals and mares during the postpartum period. The vaginal microbiota was examined in six mares. Swabs were taken from the vaginal caudal wall within 12 h after natural delivery. Next-generation sequencing was used to analyze the composition of the vaginal microbiota and identify shared bacterial taxa. The post-delivery vaginal microbiome of mares included 18 identified families, 25 genera, and 33 species. The core families of the mares' microbiome comprised Leptotrichiaceae (21.72%), Peptostreptococcaceae/Tisserellales (15.54%), Corynebacteriaceae (13.32%), Aerococcaceae (10.84%), and Campylobacteraceae (4.26%). Shared bacterial species included Corynebacterium kutsheri, Campylobacter spp., Facklamia spp., and Oceanivirga uncultured bacteria. We found the presence of various Corynebacterium and Streptococcus species that could be involved in uterine disorders. Further research should focus on the possible pathogenicity of these bacteria for mares in the postpartum period and newborn foals.