Department of Veterinary Sciences, University of Turin, 10095, Grugliasco (TO), Italy.
Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.
BMC Vet Res. 2024 Aug 12;20(1):363. doi: 10.1186/s12917-024-04225-2.
Microbial colonization during early life has a pivotal impact on the host health, shaping immune and metabolic functions, but little is known about timing and features of this process in dogs. The objectives of this study were to characterize the first step of intestinal microbiota development in naturally delivered canine puppies and to investigate its relationship with the maternal bacterial flora, using traditional culture and molecular analyses. Sixty puppies of two breeds, Appenzeller Cattle Dog (n = 3 dams) and Lagotto Romagnolo (n = 6), housed in the same breeding kennel, were included in the study. Swabs were collected in duplicate (for culture and for molecular analysis) from the dams' vagina and rectum at the end of parturition, from puppies' rectum, before maternal care, and from the environment (floor of the nursery and parturition box).
93.3% meconium samples showed bacterial growth, limited to a few colonies in 57.0% of cases. High growth was detected for Enterococcus faecalis, which was the most frequently isolated bacterium. The genus Enterococcus was one of the most represented in the dams' rectum and vagina (88.9% and 55.6%, respectively). The genera Staphylococcus, Enterococcus, Escherichia and Proteus were also often isolated in meconium but were usually present in maternal samples as well, together with ubiquitous bacteria (Acinetobacter, Psychrobacter). In the environmental samples, just a few bacterial species were found, all with low microbial load. Additionally, bacteria of the phyla Proteobacteria, Firmicutes, and Actinobacteria were identified in meconium through molecular analysis, confirming the culture results and the early colonization of the newborn gut. Maternal, meconium and environmental samples had similar alpha diversity, while beta-diversity showed differences among families (i.e. a dam and her litter), and association indexes revealed a significant correlation between family members and between sample origin, suggesting a strong contribution of the maternal flora to the initial seeding of the canine neonatal gut and a strong individual dam imprint.
This study showed that the meconium of vaginally delivered puppies has its own microbiota immediately after birth, and that it is shaped by the dam, which gives a specific imprint to her litter.
生命早期的微生物定植对宿主健康具有关键影响，可塑造免疫和代谢功能，但人们对狗的这一过程的时间和特征知之甚少。本研究的目的是描述自然分娩犬幼崽肠道微生物群发展的第一步，并使用传统培养和分子分析研究其与母体细菌群落的关系。本研究纳入了同一繁殖犬舍的 2 个品种的 60 只幼犬，阿彭策尔牛犬（n = 3 只母犬）和拉戈托罗马尼奥洛犬（n = 6 只）。在分娩结束时，从母犬的阴道和直肠、幼犬的直肠、母犬护理前以及环境（托儿所地板和分娩箱）中采集了 2 份阴道和直肠拭子（用于培养和分子分析）。
93.3%的胎粪样本显示有细菌生长，其中 57.0%的样本仅生长少数菌落。高生长检测到粪肠球菌，这是最常分离的细菌。肠球菌属是母犬直肠和阴道中最常见的细菌之一（分别为 88.9%和 55.6%）。葡萄球菌属、肠球菌属、大肠杆菌属和变形菌属也经常在胎粪中分离出来，但也通常存在于母本样本中，还有无处不在的细菌（不动杆菌属、嗜冷杆菌属）。在环境样本中，只发现了少数几种细菌，且微生物负荷都很低。此外，通过分子分析还在胎粪中鉴定出了变形菌门、厚壁菌门和放线菌门的细菌，证实了培养结果和新生肠道的早期定植。母体、胎粪和环境样本具有相似的 alpha 多样性，而 beta 多样性则显示出家族之间的差异（即一只母犬及其幼崽），关联指数显示家族成员之间以及样本来源之间存在显著相关性，这表明母体菌群对犬新生肠道的初始定植具有重要贡献，并且母犬对其幼崽有很强的影响。
本研究表明，阴道分娩的幼犬胎粪在出生后立即具有自己的微生物群，并且由母犬塑造，这使其幼崽具有特定的印记。
