The study, published in the US journal Pediatrics, did not say why but suggested that being around a dog that spends at least part of its day outdoors may boost a child’s immune system in the first year of life.
Cats, too, seemed to convey some protection to babies, though the effect observed was weaker than with dogs.
The research was based on 397 children in Finland whose parents made diary entries each week recording the state of their child’s health during the infant’s first year, from nine weeks to 52 weeks of age.
Overall, babies in homes with cats or dogs were about 30 percent less likely to have respiratory infectious symptoms — which included cough, wheezing, rhinitis (stuffy or runny nose) and fever — and about half as likely to get ear infections.
“If children had dog or cat contacts at home, they were significantly healthier during the study period,” said the study led by experts at Kuopio University Hospital in Finland.
The most protective association was seen in children who had a dog inside at home for up to six hours a day, compared to children who did not have any dogs or who had dogs that were always outside.
“We offer preliminary evidence that dog ownership may be protective against respiratory tract infections during the first year of life,” said the study.
“We speculate that animal contacts could help to mature the immunologic system, leading to more composed immunologic response and shorter duration of infections.”
The improvement was significant, even after researchers ruled out other factors that could boost infection risk, such as not having been breastfed, attending daycare, being raised by smokers or parents with asthma, or having older siblings in the household.
In addition to having less frequent ear infections and respiratory infections, babies near dogs tended to need fewer courses of antibiotics compared to those who were reared in pet-free households, it said.
Previous research has shown conflicting results, with some studies finding no benefit for young children being around furry pets and others finding that animal contact appears to offer some protection against colds and stomach ailments.
The study authors said their research differs from previous analyses because it focuses solely on the first postnatal year and does not include older children.