Dogs are no longer just man's best friend: The furry family members may also protect infants against breathing problems and infections, a new study suggests.
Researchers found that Finnish babies who lived with a dog or - to a lesser extent - a cat spent fewer weeks with ear infections, coughs or running noses. They were also less likely to need antibiotics than infants in pet-free homes.
Dr. Eija Bergroth from Kuopio University Hospital in Finland and colleagues said one possible explanation for that finding is that dirt and allergens brought in by animals are good for babies' immune systems.
The researchers studied 397 infants who were born at their hospital between September 2002 and May 2005 for their first year.
Parents filled out weekly diaries starting when the child was nine weeks old, recording information on babies' health as well as their contact with cats and dogs.
Based on those diaries and a year-end questionnaire, the researchers determined that 35 percent of the children spent the majority of their first year with a pet dog and 24 percent in a home with a cat.
Despite only a third of families owning dogs and fewer owning cats, the majority of babies had at least some contact with a dog at their house during the study period and more than one-third were exposed to a cat.
Before their first birthday, 285 of the babies had at least one fever, 157 had an ear infection, 335 had a cough, 128 wheezed, 384 got stuffy or runny noses and 189 needed to take antibiotics at some point, parents reported.
The researchers found that contact with dogs, more than cats, was tied to fewer weeks of sickness for babies.
For example, infants with no dog contact at home were healthy for 65 percent of parents' weekly diary reports. That compared to between 72 and 76 percent for those who had a dog at home.
Babies in dog-owning families were also 44 percent less likely to get inner ear infections and 29 percent less likely to need antibiotics.
The researchers said infants who spent more than zero but less than six hours per day at home with a dog were the least likely to get sick. "A possible explanation for this interesting finding might be that the amount of dirt brought inside the home by dogs could be higher in these families because (the dog) spent more time outdoors," the researchers wrote Monday in the journal Pediatrics.
Bergroth told Reuters Health in an email that the dirt and germs a dog brings into the house may cause a child's immune system to mature faster, which makes it better at defending against the viruses and bacteria that cause respiratory problems.
That theory is commonly referred to as the "hygiene hypothesis."
"In many ways, (the study is) saying, if you're exposed to a natural environment… your immune system recognizes that you don't fight the normal allergens," said Dr. T. Bernard Kinane, the chief of the pediatric pulmonary unit at MassGeneral Hospital for Children in Boston.
Kinane, who was not involved with the new study, told Reuters Health not all research agrees that exposure to dogs and cats helps protect against kids' breathing problems. But he said there is an overall trend in that direction.
The researchers also can't rule out the possibility that people who own dogs are less likely to get sick for another reason, and not due to protection offered by pets, Bergroth noted.