The study might seem somewhat unique in its subject matter, but it adds to a fascinating area of investigation as we are only just beginning to understand the impact of the human gut microbiome on a range of health outcomes. For this study, researchers asked mothers about their pet ownership prior to birth, and at 3 months post-partum . They profiled the infant gut microbiota with 16S rRNA sequencing from stool samples collected around the three-month mark and categorised the babies in terms of their pet exposure.
The results are very interesting! They found the following:
“As a common effect in all birth scenarios, pre- and postnatal pet exposure enriched the abundance of Oscillospira and/or Ruminococcus (P <0.05) with more than a twofold greater likelihood of high abundance. Among vaginally born infants with maternal Streptoccoaceae were substantially and significantly reduced by pet exposure,… reflecting an 80% decreased likelihood of high abundance for pet exposure alone and a 69% reduced likelihood for exposure in the pre-and postnatal time periods.”
Why is this significant? Oscillospira and Ruminococcus have been associated with childhood obesity and allergies. Lead researcher Anita Kozyrskyj told Science Daily that:
“The abundance of these two bacteria were increased twofold when there was a pet in the house,” said Kozyrskyj, adding that the pet exposure was shown to affect the gut microbiome indirectly — from dog to mother to unborn baby — during pregnancy as well as during the first three months of the baby’s life. In other words, even if the dog had been given away for adoption just before the woman gave birth, the healthy microbiome exchange could still take place .”
An interesting finding of the study is that the results were independent of the mother’s asthma and allergy status, her breastfeeding status, or other home characteristics . Likewise, the immune-boosting effect occurred in three birth scenarios known to reduce immunity – Caesarean section births, antiobiotics during birth, and when a mother does not or cannot breastfeed .
There is also a suggestion that “the presence of pets in the house reduced the likelihood of the transmission of vaginal GBS (group B Strep) during birth .” This particular strain of Strep is known to cause pneumonia in newborns, hence the widespread administration of antibiotics to affected mothers during birth.
Of course the term “Furry pet” is fairly vague. For the sake of clarification, 70% of the pets in the study were dogs, and researchers theorise that “exposure to dirt and bacteria in early life — for example, in a dog’s fur and on its paws – can create early immunity. ” At this point, researchers aren’t sure of the exact mechanism that enables this effect.
This study builds on the work of Nermes et al  published in the Journal of Allergy and Clinical Immunology in 2015. That study took fecal samples from infants at 6 months of age and utilised skin prick tests to assess their allergy status. The authors remarked that:
“The traditional conception of exposure to pets as environmental triggers of asthma and allergic symptoms was challenged by reports on a protective effect of early cat or dog exposure for atopy, allergic rhinitis, or asthma. A recent meta-analysis of birth-cohort studies, however, found no effect of early pet ownership on asthma or allergic rhinitis at school age. Another meta-analysis on pet exposure and the risk of atopic dermatitis reported a protective effect of exposure to dogs and pets overall on the risk of atopic dermatitis in childhood.”
Together, these studies continue to challenge the historical idea that dogs and cats may actually provoke or stir up allergies. Encouragingly, the truth may be quite the reverse. So if you’ve been putting off the puppy purchase until after your kiddies are born, perhaps its time to rethink.
 Tun H, Konya T, Takaro T, Brook J, Chari R, Field C, Guttman D, Becker A, Mandhane P, Turvey S, Subbarao P, Sears M, Scott J, Kozyrskyj A and CHILD Study Investigators (2017), “Exposure to Household Furry Pets Influences the Gut Microbiota of Infants and 3-4 Months Following Various Birth Scenarios,” Microbiome (Bio Med Central), https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-017-0254-x retrieved 18 April 2017,
 University of Alberta Faculty of Medicine & Dentistry. “Pet exposure may reduce allergy and obesity: Research shows having a dog early in life may alter gut bacteria in immune-boosting ways.” ScienceDaily. ScienceDaily, 6 April 2017. www.sciencedaily.com/releases/2017/04/170406143845.htm
 Nermes M, Endo A, Aarnio J, Salminen S, Isolauri E (2015), “Furry pets modulate gut microbiota composition in infants at risk for allergic disease,” Journal of Allergy and Clinical Immunology, http://dx.doi.org/10.1016/j.jaci.2015.07.029