Exposing babies to puppies and other furry pets might help them accumulate two types of bacteria in their gut that are associated with a lower risk of allergies and obesity, a Canadian study suggests.
When researchers analyzed fecal samples from 746 babies, they found having dogs and cats in the home during pregnancy and early infancy was associated with higher levels of two gut microbes: Ruminococcus and Oscillospira, which have been linked with lower odds of allergies and obesity, respectively.
"The concept of a 'dog intervention' during pregnancy as a preventive measure for allergies and obesity is not too far-fetched, but definitive studies are required to provide evidence for this health benefit," said senior study author Anita Kozyrskyj, a pediatrics researcher at the University of Alberta.
While the study doesnít prove pets directly prevent allergies or obesity or demonstrate how cats and dogs cause changes in gut bacteria, itís possible that pet exposure during pregnancy may influence the composition of gut microbes in the infant by affecting the motherís vaginal or skin microbes, Kozyrskyj said by e-mail.
Changes in the motherís microbes might be passed on during birth, even with a surgical delivery, Kozyrskyj added. After that, pets might directly transfer beneficial microbes when they touch babies, and infants may also pick up pet microbes that are left on household surfaces or in dust.
About 45 percent of the households in the study didnít have any pets, and another 8 percent only had animals during pregnancy, researchers report in the journal Microbiome.
Among the homes with pets both during pregnancy and afterwards, 44 percent had only dogs, 34 percent had just cats and 20 percent had at least one of each.
Regardless of the way babies were delivered, they were more than twice as likely to have high levels of Ruminococcus and Oscillospira when they were exposed to furry creatures while in the womb or during infancy.
Among vaginally delivered babies whose mothers got antibiotics to prevent group B Streptococcus transmission during birth, infants exposed to pets in utero or after delivery had lower levels of Streptococcaceae bacteria in their feces. This family of bacteria can cause pneumonia in infants.
Pet exposure was also linked to lower fecal levels of Enterobacteria even among babies born by emergency cesarean who normally have high levels of these microbes at three months of age. These bacteria are associated with Salmonella and other infections.
The study isnít a controlled experiment designed to prove that pets prevent diseases, the authors note.
Still, the findings add to growing evidence linking exposure to household pets and farm animals with a lower risk of health problems like asthma and allergies, said Tove Fall, a researcher at Uppsala University in Sweden who wasnít involved in the study.
"This study shows that some bacteria are more common in the gut flora of children born in homes with petsóthese findings need to be replicated in other studies," Fall said by e-mail. "It is not known how these bacteria affect the child health, but in general a higher diversity and richness of the gut flora is thought to help to protect the child from diseases linked to the immune system."