Could exposure to dog and farm animals be the key to protecting children from asthma?

It has long been debated whether or not these kinds of exposures can influence the immune system of children. Childhood asthma is a concern throughout the world and somewhat alarmingly, over the last decade there has been an increasing incidence.

Risk factors for children include exposure to tobacco smoke, socioeconomic factors and family history.

What previous research has told us is that children exposed to farm animals leads to a 25 per cent reduction in overall asthma prevalence compared to those children not exposed.

The question is whether exposure to pets such as dogs in early childhood is also able to confer the same kind of risk reduction.

The theory behind this question is that children exposed to animals - either dogs or farm animals - are then in contact with many more microorganisms than kids who are not. The researchers sought to answer the question whether this is a true relationship.

The study:

Over a 10 year period Swedish children were studied for the association between early exposure to dogs and farm animals and the use of asthma medication and diagnosis of asthma.

Children ages 1 to 5 and then children at 6 years of age were used in the study.

This was a large study with over 1 million children studied over that time period. In this group some 14 per cent were exposed to dogs and much smaller percentage of 0.5 per cent or 1/2 a per cent were exposed to farm animals.

The study found that exposure to a dog during the first year of life was associated with a decreased risk of asthma in school age children as well as in preschool children aged 3 and older.

The impact was not seen in children younger than 3 years old. The same held true for exposure to farm animals and reducing asthma in children in general.

These results were consistent for first born children among parents with and without asthma.