Growing up with a dog linked to reduced risk of asthma, study says

Having a dog in the home and contact with farm animals during a child’s earlier years can reduce their risk of asthma, according to new research.

The study, published in the journal JAMA Pediatrics, examined data on over 1 million children born in Sweden – where dog and farm animal ownership registration is required by law – from 2001 to 2010.

Researchers concluded that exposure to a dog in a child’s first year decreases the likelihood of asthma by 15 percent; living in close proximity to farm animals drops the risk by 52 percent.

Findings back the “hygiene hypothesis,” which suggests that living in very clean environments during early life can make people more prone to allergy conditions, including asthma. Without early exposure to microbes and parasites, according to the hypothesis, the immune system may be stunted.

“We know that children with established allergy to cats or dogs should avoid them, but our results also indicate that children who grow up with dogs have reduced risks of asthma later in life,” said Catarina Almqvist, co-author of the study from Sweden’s Karolinska Institute.

Lead scientist Dr. Tove Fall from Uppsala University in Sweden pointed out that previous studies have indicated that growing up on a farm cuts a child’s chances of developing asthma by about half and that researchers wanted to see if the relationship was the same for children growing up with dogs in their homes.

“Our results confirmed the farming effect and we also saw that children who grew up with dogs had about 15 [percent] less asthma than children without dogs,” Fall said.

The study was made possible because of Sweden’s organized system of national databases, which are accessible to scientists. In addition to the documentation of farm animal ownership, each visit to specialist physicians and every prescription issued is recorded.

“Because we had access to such a large and detailed data set, we could account for confounding factors such as asthma in parents, area of residence and socio-economic status,” Fall said.

Despite the study’s findings, Erika Kennington, head of research at Asthma UK, an asthma charity in the United Kingdom, said additional research is needed.

“Asthma is a complex condition with many different types and causes … more research … will help us better understand the effects so that it can be turned into practical advice for parents of young children,” Kennington said.