Dog exposure in infancy linked to lower childhood asthma risk, study finds

A presentation at the European Respiratory Society Congress in Amsterdam highlighted evidence that early exposure to dog allergens in the home may reduce the risk of childhood asthma, while exposure to cat allergens does not appear to offer the same protection.

In the study, researchers analyzed dust from the homes of 1,050 infants aged three to four months and tracked the children until they were five years old. About 6.6% were diagnosed with asthma by that age. Those exposed to higher levels of Can f1, an allergen shed in dog skin and saliva, had a 48% lower risk of developing asthma compared with their peers with lower exposure. They also showed better lung function, as measured by a one-second forced expiratory volume test after a deep breath. The protective effect was strongest among children who carried a higher genetic risk for poorer lung function, according to researchers from the Hospital for Sick Children in Toronto, Canada.

The researchers stressed that cat allergens or bacterial endotoxin did not convey the same protective effect. Lead author Dr. Jacob McCoy said the findings suggest that early exposure to dog allergens might prevent sensitisation, possibly by altering the nasal microbiome or influencing immune development, though the exact mechanism remains unknown. “In this study, we examined pet allergens from dogs and cats. We found that, while cat allergens showed no association, exposure to dog allergens was linked to improved lung function and a reduced risk of asthma,” McCoy said. He added that while sensitivity to dog allergens can worsen asthma symptoms later in life, early exposure could play a protective role against the development of asthma in early childhood.

Experts cautioned that the results do not mean families should try to keep dogs around at all costs. Dr. Erol Gaillard, chair of the European Respiratory Society’s paediatric asthma and allergy expert group, noted that the finding is potentially encouraging but requires more research to understand long-term effects on developing lungs.

“This is potentially good news for families with pet dogs; however, we need to know more about this link and how living with pets affects children’s developing lungs in the longer term,” Gaillard said.

Sarah Sleet, chief executive of Asthma and Lung UK, said the study challenges previous guidance that often recommended removing pets from homes with wheezy or at-risk children. “So, this new research suggesting a dog in the home could actually reduce the risk of developing asthma is fascinating, although we will need more research to understand what it is about dogs that makes the difference,” Sleet said. She also called for greater investment in lung research to clarify causes, prevention, and treatment of asthma.

The congress program also showcased advances in imaging and diagnostics for lung disease. Delegates were told about a robot-assisted bronchoscope designed to reach very small lung tumors and collect samples. Used alongside a CT scanner, the technology was tested in 78 patients with abnormal growths; the conventional technique reached and biopsy-tested 23% of the tumors, while the robot-assisted approach achieved biopsy for more than 84% of the tumors. The kit costs about one million euros, and researchers stressed it could enable earlier, less invasive diagnosis of lung cancer when paired with imaging technologies.

Asthma remains a major chronic respiratory condition in children, influenced by a complex mix of genetic and environmental factors, including infections, allergies, and air pollution. The researchers said the indoor environment is an important focus for potential risk modification, given that children spend most of their time indoors.

Overall, the study points to a potential protective role for dog allergens in early life, while underscoring the need for further research to understand mechanisms, long-term outcomes, and how lifestyle choices might influence asthma risk from infancy through early childhood.