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The new study confirmed earlier research showing that children who grow up on farms have lower rates of asthma. Fall and colleagues reviewed data on more than one million children born in Sweden from 2001 through 2010.
“Earlier studies have shown that growing up on a farm reduces a child’s risk of asthma to about half…” Small studies with limited numbers of people have turned up varying and sometimes contradictory results.
Other factors that might connect animal ownership to lower asthma risk include the potential for kids who live with dogs or on farms to spend more time outside and get less indoor allergen exposure and live outside polluted urban areas, Virant, who wasn’t involved in the study, said by e-mail.
Fall said she and her team are presently working on projects aiming to characterize dogs’ impact on children’s gut microbiome and to investigate whether there are differences in effects of various dog breeds on the risk of asthma. In fact, about 8% of children in theUnited States suffered from the disease in 2013.
For the study, they tracked 650,000 children and found that those who had grown up with a dog in their home were less likely to have asthma at the age of seven than children without dogs.
Exposure to dogs and farm animals during the first year of life cut the risk of asthma for preschoolers, too, the authors found. “One of the main hypotheses at the moment is that kids in animal environments breathe air that contains more bacteria and bacterial fragments, which actually could lower their risk of asthma”.
Given the size of the study, plus big pet and farming cultures here in the United States, it’s probably not a stretch to assume Fido and farms could help protect American babies, too.
The study has several limitations, including that it was restricted to the Swedish population and that the researchers followed children only up to age 7, so later effects are unknown.
The additional exposure may not be all good news, though. Dog exposure during the first year of life was associated with a decreased risk of asthma in school-aged children and in preschool-aged children three years or older, but not in children younger than three years. They noted that this information might be helpful in decision making for families and physicians on the appropriateness and timing of early animal exposure.
The authors are affiliated with Uppsala University, Uppsala, Sweden; Karolinska Institutet, Stockholm, Sweden; Örebro University Hospital, Örebro, Sweden; and Swedish University of Agricultural Sciences, Uppsala, Sweden.
