Children that grow up with animals less likely to develop asthma

A study in Sweden has found that children are less likely to suffer asthma if they grow up in a household with a dog compared to dog-less homes. This study – the largest of its kind (records of 376,638 preschool children and 276,298 school-age children were analyzed)- explored the link between respiratory disease and early exposure to animals. Researchers gathered data from the country’s national medical records system with the national dog-license register to examine the relationship between dog ownership during the child’s first year and the occurrence of asthma in children up to age six. Researchers determined that children who had grown up with dogs since birth had a 15% decreased risk of asthma by age six compared to those who had grown up without a dog.

The researchers also examined the link between exposure to farm animals and asthma and found that those who grew up on farms were 52% less likely to develope asthma by age six, and preschool-age children experienced a 31% reduced risk.

The study, published in the journal JAMA Pediatrics, supports the “hygeiene hypothesis”, which theorizes that exposure to dirt and infectious agents from an early age decreases the chance the immune system will over react when exposed to these things later in life. By not exposing young children to these elements, the hypothesis argues, the natural development of the immune system is depressed, making children more susceptible to allergic diseases.