Babies who grow up in environments with dogs may have a lower risk of developing asthma by the age of five. This is the conclusion of a Canadian study.
The investigation, conducted by a team at the Hospital for Sick Children (SickKids) in Toronto, analyzed early exposure of babies to dog and cat allergens. The data reveal that only dog allergens appear to have a protective effect.
“Asthma is one of the most common chronic respiratory diseases in childhood, particularly in the first four years of life,” explains Jacob McCoy, one of the study’s authors, quoted in a press release. “We wanted to understand how allergens present in the home, especially those from pets, may influence the development of the disease,” he adds.
The study involved 1,050 children participating in the Canadian CHILD cohort. Dust samples were collected from the babies’ homes between three and four months of age. In these samples, the researchers measured the presence of three substances: Can f1, a protein found on dogs’ skin and saliva; Fel d1, derived from cats; and endotoxins, associated with bacteria.
At five years of age, the children were evaluated by physicians for the presence of asthma, through clinical tests and pulmonary function, namely FEV1 (forced expiratory volume in the first second). Blood samples were also analyzed to determine genetic factors related to the risk of asthma and allergies.
The results show that babies exposed to higher levels of the dog allergen Can f1 had about a 48% lower probability of developing asthma by age five. In addition, these babies exhibited better lung function, especially those with a greater genetic predisposition to respiratory diseases. Exposure to cat allergens or to endotoxins did not demonstrate any similar benefit.
“Although it is already known that sensitization to dog allergens can worsen symptoms in people with asthma, our data suggest that early exposure may, in fact, prevent this sensitization. This could be related to changes in the nasal microbiome or effects on the immune system,” says McCoy.
The scientific community considers the results promising, though it acknowledges that more investigations are needed. Erol Gaillard, chair of the ERS pediatric asthma specialists group and associate professor at the University of Leicester, underscores the importance of the study.
“Asthma is the most common chronic condition among children and young people, and one of the leading causes of hospital admission. This study offers a new perspective: growing up with dogs may provide some protection. However, there is still much to understand about the impact that animals have on children’s lung development over time,” says the expert, who was not involved in the investigation.
