Puppy meconium microbiome in relation with vaginal and faecal dam microbiome

Knowledge of the microbial flora of the meconium and of its colo- nization timing and pathways is limited in puppies. The aim of this study was to evaluate the characteristics of the early meconium microbiota by collecting the samples immediately after birth and before maternal care and suckling. Four litters (N = 24 puppies) of each of two medium size breeds, Appenzeller Cattle Dog and Lagotto Romagnolo, housed in the same breeding kennel and fed the same dry commercial diet, were examined (bitches' age, mean ± SD: 4.6 ± 1.4 years). No antimicrobials or supplements were administered during pregnancy; all parturitions were natural (mean litter size: 6.0 ± 2.4). Mini-swabs were used to collect meconium samples from the rectum of the neonates. Samples were also collected from the vagina and rectum of dams at the end of parturition. Environmental controls were performed. Microbiota was investigated by 16S rRNA sequencing. Nucleic acids were extracted using the RNeasy Power Microbiome kit (Qiagen). Illumina libraries were created, and data were analysed using Qiime2 (standard pipeline) and R (cluster analy- sis). Taxonomic identification results were obtained (Silva database). Meconium had a low number of bacteria, with high diversity, and did not differ from the environmental samples. Bacteria from the phyla Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, and Fusobacteria were detected. Association indices showed a sig- nificant correlation between samples from the same dam-litter pairs. These results confirm the observations made by culture-dependent methods [1]: meconium colonization begins immediately, with small numbers of different bacteria, and the dam imprints the initial intes- tinal colonization of her puppies. [1] Del Carro, BMC Vet Res, 2022;18.