A study in Sweden (Fall et al.) published in 2015 combined medical data from over one million children born there between 2001 and 2010, with data on dog and farm animal ownership (registration of which is a legal requirement in Sweden). The hypothesis that exposure to dogs and farm animals during the first year of life reduces the risk of asthma in children at age 6 years was supported by the data. “The results were robust and independent of parental asthma or whether the child was first-born,” the authors say.

SEE ALSO | Hedgerows in the UK. / Hygiene hypothesis.


Fall T, Lundholm C, Örtqvist AK, Fall K, Fang F, Hedhammar Å, Kämpe O, Ingelsson E, Almqvist C. Early Exposure to Dogs and Farm Animals and the Risk of Childhood Asthma. JAMA Pediatr. 2015;169(11):e153219. doi:10.1001/jamapediatrics.2015.3219.