A dog in the house 'can protect against asthma'
3rd November 2015 - Having a dog in the house could help protect a young baby from developing asthma later in childhood, a study has concluded.
The analysis also found an even stronger protective effect from being surrounded by farm animals.
A number of environmental factors have been associated with either a higher or lower risk of asthma. "Earlier studies have shown that growing up on a farm reduces a child’s risk of asthma to about half," says Tove Fall, an assistant professor in epidemiology at Uppsala University in Sweden who led the research. "We wanted to see if this relationship also was true also for children growing up with dogs in their homes."
Analysing a million births
The researchers drew on data from all of the 1 million plus children born in Sweden from 2001 to 2010. Of these:
- 14.2% of pre-school children aged 1 to 5 had been exposed to dogs
- 0.5% of pre-school children had been exposed to farm animals
- 8.2% of school-age children had been exposed to dogs
- 0.3% of school-aged children had been exposed to farm animals.
They found that 5% of those in the pre-school age group were treated for asthma symptoms, while 4.2% developed asthma symptoms when they were aged 6.
Dogs and farm animals
They conclude that babies exposed to dogs during the first year of life had a 13% lower risk of asthma before school age. Exposure to farm animals was associated with a 31% lower risk of asthma during pre-school years and a 52% lower risk of asthma in school-aged children.
"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 say. "This information might be helpful in decision making for families and physicians on the appropriateness and timing of early animal exposure."
Tove Fall has commented that the results fit with the hygiene hypothesis which favours exposure to dust and dirt to improve our tolerance of common allergens. He says couples who are pregnant or are planning to have a baby shouldn't worry about getting a dog or a puppy if they want one.
However, she stresses that getting a dog will not cure a child's allergies and could make them worse.
'More studies needed'
Commenting on the study in the journal JAMA Pediatrics, Erika Kennington, Head of Research at Asthma UK, says in an emailed statement: “Asthma is a complex condition with many different types and causes. Whilst this study identifies a link to living with a dog or regular exposure to farm animals in the first year of a child's life, and their chance of developing asthma by the age of 6, more research is needed.
"This will help us better understand the effects so that it can be turned into practical advice for parents of young children."