{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T11:53:39Z","timestamp":1791287619446,"version":"4.1.0"},"reference-count":45,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2023,5,4]],"date-time":"2023-05-04T00:00:00Z","timestamp":1683158400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Veterinary Sciences"],"abstract":"<jats:p>At present, there are no data on the presence of bacteria in healthy canine and feline pregnancies at term. Here, we investigated the uterine microbiome in bitches (n = 5) and queens (n = 3) undergoing elective cesarean section in two facilities. Samples included swabs from the endometrium, amniotic fluid, and meconium, and environmental swabs of the surgical tray as controls. Culture and 16S rRNA gene sequencing were used to investigate the presence of bacteria. Culture was positive for 34.3% of samples (uterus n = 3, amniotic fluid n = 2, meconium n = 4, controls n = 0), mostly with low growth of common contaminant bacteria. With sequencing techniques, the bacterial abundance was significantly lower than in environmental controls (p &lt; 0.05). Sequencing results showed a species-specific pattern, and significant differences between canine and feline bacterial populations were found at order, family, and genus level. No differences were found in alpha and beta diversities between feto-maternal tissues and controls (p &gt; 0.05). Dominant phyla were Bacteroidetes, Firmicutes, and Proteobacteria in different proportions based on tissue and species. Culture and sequencing results suggest that the bacterial biomass is very low in healthy canine and feline pregnancies at term, that bacteria likely originate from contamination from the dam\u2019s skin, and that the presence of viable bacteria could not be confirmed most of the time.<\/jats:p>","DOI":"10.3390\/vetsci10050331","type":"journal-article","created":{"date-parts":[[2023,5,5]],"date-time":"2023-05-05T02:08:42Z","timestamp":1683252522000},"page":"331","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Challenging the Hypothesis of in Utero Microbiota Acquisition in Healthy Canine and Feline Pregnancies at Term: Preliminary Data"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6061-4889","authenticated-orcid":false,"given":"Penelope","family":"Banchi","sequence":"first","affiliation":[{"name":"Department of Veterinary Sciences, University of Turin, 10095 Grugliasco, Italy"},{"name":"Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Barbara","family":"Colitti","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Turin, 10095 Grugliasco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrea","family":"Del Carro","sequence":"additional","affiliation":[{"name":"Iunovet-Clinique Vet\u00e9rinaire Saint Hubert, 06240 Beausoleil, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michela","family":"Corr\u00f2","sequence":"additional","affiliation":[{"name":"Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8181-5866","authenticated-orcid":false,"given":"Alessia","family":"Bertero","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Turin, 10095 Grugliasco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5408-6397","authenticated-orcid":false,"given":"Ugo","family":"Ala","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Turin, 10095 Grugliasco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Angela","family":"Del Carro","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Turin, 10095 Grugliasco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5010-6311","authenticated-orcid":false,"given":"Ann","family":"Van Soom","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luigi","family":"Bertolotti","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Turin, 10095 Grugliasco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ada","family":"Rota","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Turin, 10095 Grugliasco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,5,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"48","DOI":"10.1186\/s40168-017-0268-4","article-title":"A critical assessment of the \u201csterile womb\u201d and \u201cin utero colonization\u201d hypotheses: Implications for research on the pioneer infant microbiome","volume":"5","author":"Arrieta","year":"2017","journal-title":"Microbiome"},{"key":"ref_2","first-page":"237ra65","article-title":"The placenta harbors a unique microbiome","volume":"6","author":"Aagaard","year":"2014","journal-title":"Sci. Transl. Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1152","DOI":"10.2217\/fmb-2020-0243","article-title":"Evidence of bacterial DNA presence in chorionic villi and mniotic fluid in the first and second trimester of pregnancy","volume":"16","author":"Campisciano","year":"2021","journal-title":"Future Microbiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1794266","DOI":"10.1080\/19490976.2020.1794266","article-title":"The meconium microbiota shares more features with the amniotic fluid microbiota than the maternal fecal and vaginal microbiota","volume":"12","author":"He","year":"2020","journal-title":"Gut Microbes"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"23129","DOI":"10.1038\/srep23129","article-title":"Human gut colonisation may be initiated in utero by distinct microbial communities in the placenta and amniotic fluid","volume":"6","author":"Collado","year":"2016","journal-title":"Sci. Rep."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"e127806","DOI":"10.1172\/jci.insight.127806","article-title":"Fetal exposure to the maternal microbiota in humans and mice","volume":"4","author":"Younge","year":"2019","journal-title":"JCI Insight"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"626421","DOI":"10.3389\/fmicb.2021.626421","article-title":"The Composition of the Microbiota in the Full-Term Fetal Gut and Amniotic Fluid: A Bovine Cesarean Section Study","volume":"12","author":"Husso","year":"2021","journal-title":"Front. Microbiol."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Rota, A., Del Carro, A., Bertero, A., Del Carro, A., Cucuzza, A.S., Banchi, P., and Corr\u00f2, M. (2021). Does Bacteria Colonization of Canine Newborns Start in the Uterus?. Animals, 11.","DOI":"10.3390\/ani11051415"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1016\/j.theriogenology.2015.03.002","article-title":"Occurrence of bacteria and polymorphonuclear leukocytes in fetal compartments at parturition; relationships with foal and mare health in the peripartum period","volume":"84","author":"Hemberg","year":"2015","journal-title":"Theriogenology"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"6875","DOI":"10.1038\/s41598-022-10869-7","article-title":"Comprehensive human amniotic fluid metagenomics supports the sterile womb hypothesis","volume":"12","author":"Wang","year":"2022","journal-title":"Sci. Rep."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"248.e1","DOI":"10.1016\/j.ajog.2020.01.056","article-title":"Midtrimester amniotic fluid from healthy pregnancies has no microorganisms using multiple methods of microbiologic inquiry","volume":"223","author":"Liu","year":"2020","journal-title":"Am. J. Obstet. Gynecol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"19449","DOI":"10.1038\/s41598-021-98951-4","article-title":"2021 Presence of distinctive microbiome in the first-pass meconium of newborn infants","volume":"11","author":"Turunen","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"865","DOI":"10.1038\/s41564-021-00904-0","article-title":"Fetal meconium does not have a detectable microbiota before birth","volume":"6","author":"Kennedy","year":"2021","journal-title":"Nat. Microbiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/j.vetimm.2018.09.005","article-title":"Fetal environment and fetal intestine are sterile during the third trimester of pregnancy","volume":"204","author":"Malmuthuge","year":"2018","journal-title":"Vet. Immunol. Immunopathol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"e00933-19","DOI":"10.1128\/mSphere.00933-19","article-title":"No Consistent Evidence for Microbiota in Murine Placental and Fetal Tissues","volume":"5","author":"Theis","year":"2020","journal-title":"mSphere 5"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"820366","DOI":"10.3389\/fimmu.2022.820366","article-title":"Does the Amniotic Fluid of Mice Contain a Viable Microbiota?","volume":"13","author":"Winters","year":"2022","journal-title":"Front. Immunol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"639","DOI":"10.1038\/s41586-022-05546-8","article-title":"Questioning the fetal microbiome illustrates pitfalls of low-biomass microbial studies","volume":"613","author":"Kennedy","year":"2023","journal-title":"Nature"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1016\/j.tim.2018.11.003","article-title":"Contamination in Low Microbial Biomass Microbiome Studies: Issues and Recommendations","volume":"27","author":"Eisenhofer","year":"2019","journal-title":"Trends Microbiol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.theriogenology.2020.04.014","article-title":"Do newborn puppies have their own microbiota at birth? Influence of type of birth on newborn puppy microbiota","volume":"152","author":"Kalin","year":"2020","journal-title":"Theriogenology"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1127","DOI":"10.1126\/science.1070633","article-title":"Isolating \u201cuncultivable\u201d microorganisms in pure culture in a simulated natural environment","volume":"296","author":"Kaeberlein","year":"2002","journal-title":"Science"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1124","DOI":"10.3389\/fmicb.2019.01124","article-title":"The Not-so-Sterile Womb: Evidence That the Human Fetus Is Exposed to Bacteria Prior to Birth","volume":"10","author":"Stinson","year":"2019","journal-title":"Front. Microbiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/j.jcpa.2020.02.008","article-title":"Canine Brachycephaly: Anatomy, Pathology, Genetics and Welfare","volume":"176","author":"Ekenstedt","year":"2020","journal-title":"J. Comp. Pathol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1186\/s13028-022-00664-9","article-title":"Prevalence of cesarean sections in swiss Bernese Mountain Dogs (2001\u20132020) and identification of risk factors","volume":"64","author":"Schrank","year":"2022","journal-title":"Acta Vet. Scand."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"106514","DOI":"10.1016\/j.anireprosci.2020.106514","article-title":"Ultrasonographic analysis of fetal gastrointestinal motility during the peripartum period in the dog","volume":"219","author":"Milani","year":"2020","journal-title":"Anim. Reprod. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1136","DOI":"10.1111\/rda.13216","article-title":"Comparing the values of progesterone in the blood of bitches as measured with an chemiluminescence immunoassay and a radioimmunoassay","volume":"53","year":"2018","journal-title":"Reprod. Domest. Anim."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1577","DOI":"10.1111\/j.1476-5381.2010.00872.x","article-title":"Animal research: Reporting in vivo experiments: The ARRIVE guidelines","volume":"160","author":"Kilkenny","year":"2010","journal-title":"Br. J. Pharmacol."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Du Sert, N.P., Hurst, V., Ahluwalia, A., Alam, S., Avey, M.T., Baker, M., Browne, W.J., Clark, A., Cuthill, I.C., and Dirnagl, U. (2020). The ARRIVE guidelines 2.0: Updated guidelines for reporting animal research. PLoS Biol., 18.","DOI":"10.1371\/journal.pbio.3000410"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Tsuchida, S., Umemura, H., and Nakayama, T. (2020). Current Status of Matrix-Assisted Laser Desorption\/Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) in Clinical Diagnostic Microbiology. Molecules, 25.","DOI":"10.3390\/molecules25204775"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"852","DOI":"10.1038\/s41587-019-0209-9","article-title":"Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2","volume":"37","author":"Bolyen","year":"2019","journal-title":"Nat. Biotechnol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"100","DOI":"10.2307\/2346830","article-title":"Algorithm AS 136: A K-means clustering algorithm","volume":"28","author":"Hartigan","year":"1979","journal-title":"Appl. Stat."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"964","DOI":"10.1016\/j.cmi.2018.03.030","article-title":"Contaminants in blood cultures: Importance, implications, interpretation and prevention","volume":"24","author":"Cormier","year":"2018","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"355","DOI":"10.3201\/eid1302.060858","article-title":"Catheter-related bacteremia and multidrug-resistant Acinetobacter lwoffii","volume":"13","author":"Tega","year":"2007","journal-title":"Emerg. Infect. Dis."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1268","DOI":"10.1086\/374847","article-title":"Considerations in control and treatment of nosocomial infections due to multidrug-resistant Acinetobacter baumannii","volume":"36","author":"Urban","year":"2003","journal-title":"Clin. Infect. Dis."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1111\/apm.13010","article-title":"The environmental occurrence of Pseudomonas aeruginosa","volume":"128","author":"Crone","year":"2020","journal-title":"APMIS"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"2093","DOI":"10.1128\/JCM.02559-10","article-title":"Spread of Pseudomonas fluorescens due to contaminated drinking water in a bone marrow transplant unit","volume":"49","author":"Wong","year":"2011","journal-title":"J. Clin. Microbiol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"2080","DOI":"10.1071\/AN20010","article-title":"Prenatal establishment of the foal gut microbiota: A critique of the in utero colonisation hypothesis","volume":"60","author":"Mols","year":"2020","journal-title":"Anim. Prod. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Dreikausen, L., Blender, B., Trifunovic-Koenig, M., Salm, F., Bushuven, S., Gerber, B., and Henke, M. (2023). Analysis of microbial contamination during use and reprocessing of surgical instruments and sterile packaging systems. PLoS ONE, 18.","DOI":"10.1371\/journal.pone.0280595"},{"key":"ref_38","first-page":"6","article-title":"Individual Signatures Define Canine Skin Microbiota Composition and Variability","volume":"4","author":"Altet","year":"2017","journal-title":"Front. Vet. Sci."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Older, C.E., Diesel, A.B., Lawhon, S.D., Queiroz, C.R.R., Henker, L.C., and Rodrigues Hoffmann, A. (2019). The feline cutaneous and oral microbiota are influenced by breed and environment. PLoS ONE, 14.","DOI":"10.1371\/journal.pone.0220463"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"11971","DOI":"10.1073\/pnas.1002601107","article-title":"Delivery mode shapes the acquisition and structure of the initial microbiota across multiple body habitats in newborns","volume":"107","author":"Costello","year":"2010","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_41","first-page":"81","article-title":"Unculturable bacteria--the uncharacterized organisms that cause oral infections","volume":"95","author":"Wade","year":"2002","journal-title":"J. R. Soc. Med."},{"key":"ref_42","first-page":"73","article-title":"Evaluation of 5 commercial assays for the detection of Mycoplasma genitalium and other Urogenital Mycoplasmas","volume":"210","author":"Naidu","year":"2021","journal-title":"Med. Microbiol. Immunol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/j.resmic.2007.12.007","article-title":"Is meconium from healthy newborns actually sterile?","volume":"159","author":"Odriozola","year":"2008","journal-title":"Res. Microbiol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"513","DOI":"10.1016\/S0093-691X(97)00259-8","article-title":"Bacterial contamination of fetal fluids at the time of cesarean section in the cow","volume":"48","author":"Mijten","year":"1997","journal-title":"Theriogenology"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"100622","DOI":"10.1016\/j.nmni.2019.100622","article-title":"Bacterial culture through selective and non-selective conditions: The evolution of culture media in clinical microbiology","volume":"34","author":"Bonnet","year":"2019","journal-title":"New Microbes New Infect."}],"container-title":["Veterinary Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2306-7381\/10\/5\/331\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:29:16Z","timestamp":1760124556000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2306-7381\/10\/5\/331"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,5,4]]},"references-count":45,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2023,5]]}},"alternative-id":["vetsci10050331"],"URL":"https:\/\/doi.org\/10.3390\/vetsci10050331","relation":{},"ISSN":["2306-7381"],"issn-type":[{"value":"2306-7381","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,5,4]]}}}