Babies exposed to dogs and farm animals may be less likely to develop asthma by the age six, a Swedish study suggests.

Dog exposure during infancy was associated with a 13 percent lower risk of asthma in school-age children, while farm animal exposure was linked to a 52 percent risk reduction. While the findings don't prove that puppies prevent asthma, they do suggest that expectant parents may not need to give away the family pet for fear their baby might develop asthma from being around the dog, said lead study author Tove Fall of Uppsala University in Sweden. "To let children have a pet in their home is likely to enrich the family life in many ways, and perhaps also enriches the child's microbiome and immune system," Fall said by email. Fall and colleagues reviewed data on more than one million children born in Sweden from 2001 through 2010.

The analysis included about 276,000 school-age kids, including nearly 22,000 with a parent who owned a dog during the child's first year of life and about 950 with a parent who worked with farm animals. Overall, about 11,600 had an asthmatic event during their seventh year of life.

Exposure to dogs and farm animals during the first year of life cut the risk of asthma for preschoolers, too, the authors found. Preschoolers had a 10 percent lower risk of asthma if they'd been exposed to dogs, and a 21 percent lower risk with exposure to farm animals.

The study involved almost 379,000 preschool-age kids, including about 53,000 exposed to dogs and 1,700 exposed to farm animals. Children who spend a lot of time around dogs or farm animals might be exposed to bacteria that are linked to a lower risk of asthma, noted Dr. Frank Virant, an allergy researcher at the University of Washington and Seattle Children's Hospital.

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 email. Unless mom or dad are allergic, "the more animals the better," Virant said.