Children who grew up with dogs had 13% lower risk of asthma than children without dogs, according to a study published online November 2, 2015 in JAMA Pediatrics. Also, exposure to farm animals cut children’s asthma risk by half, researchers found.
Previous studies have investigated whether early childhood exposure to pets is associated with a reduced risk of asthma in children, but findings have been conflicting.
“For what we believe to be the first time in a nationwide setting, we provide evidence of a reduced risk of childhood asthma in 6-year-old children exposed to dogs and farm animals,” the authors concluded. “This information might be helpful in decision making for families and physicians on the appropriateness and timing of early animal exposure.”
In this study, researchers from Uppsala University and the Karolinska Institutet in Stockholm, Sweden, included all children—more than 1 million—born in Sweden from 2001 through 2010. The researchers analyzed 9 different national data sources, including 2 dog ownership registries not previously used for medical research.
Results showed that exposure to dogs during the first year of life was associated with a 13% decreased risk of asthma in school-age children, the researchers found. Farm animal exposure was associated with a 52% reduced risk of asthma in school-aged children, and a 31% reduced risk in preschool-age children.
Results were consistent for first-born children, among parents with and without asthma, and across different register-based definitions of asthma, the authors noted.
“We speculate that dog exposure may increase an infant’s overall exposure to microorganisms and allergens, some of which increase the risk for respiratory tract infections and others that modulate the immune system in such a way that decreases the risk of allergy-related asthma in school-aged children,” the authors wrote.