Babies exposed to dog allergens in their homes appear to have a significantly lower risk of developing asthma by the age of five, according to new research presented at the European Respiratory Society (ERS) Congress in Amsterdam. In contrast, exposure to cat allergens did not show the same protective effect.
The study, led by Dr Makiko Nanishi and presented by Dr Jacob McCoy of The Hospital for Sick Children (SickKids) in Toronto, examined how early-life exposure to pet allergens might influence asthma development and lung function.
Asthma and childhood health
Asthma remains one of the most common chronic respiratory conditions among children, particularly in the first four years of life. It arises from complex interactions between genetic predispositions and environmental exposures, including infections, allergies, and indoor air quality. Since children spend most of their early years indoors, household allergens play a critical role in shaping their respiratory health.
How the study was conducted
The research involved 1,050 children enrolled in the Canadian CHILD cohort study. Dust samples were collected from the children’s homes when they were between three and four months old. Researchers measured levels of three potential allergens:
- Can f1, a protein found in dog skin and saliva
- Fel d1, a protein found in cat skin and saliva
- Endotoxin, a molecule present on the surface of bacteria
When the children turned five, they were assessed for asthma by a physician. Their lung function was measured using forced expiratory volume in one second (FEV1). Blood samples were taken to evaluate genetic risk factors related to asthma and allergies.
Key findings
The analysis showed that babies exposed to higher levels of the dog allergen Can f1 had about a 48 percent lower risk of developing asthma. These children also showed stronger lung function.
The protective effect was even more pronounced among babies with a higher genetic risk of poor lung function. In contrast, no significant protective effect was observed from exposure to cat allergen Fel d1 or bacterial endotoxin.
Possible explanations
Researchers do not yet understand the exact mechanism. But, they believe early exposure to dog allergens may help prevent sensitisation to them. This could happen through changes in the nasal microbiome. It is the community of microbes in the nose. It could also occur through immune system modulation.
Dr McCoy explained, “While cat allergens showed no association, exposure to dog allergens was linked to improved lung function and reduced asthma risk. This suggests that early exposure could alter immune responses or microbial environments in ways that protect against asthma.”
Expert commentary
Dr Erol Gaillard, Chair of the European Respiratory Society’s expert group on paediatric asthma and allergy and Associate Professor at the University of Leicester, welcomed the findings while urging caution.
“Asthma is the most common long-term condition among children and one of the leading causes of hospital admissions,” he said. “This study suggests that babies growing up with dogs may have a lower asthma risk, which is encouraging. However, more research is needed to fully understand the long-term effects of pet exposure on children’s developing lungs.”
Implications for families
While the results point to a potential protective role for dog allergens, experts stress that more evidence is needed before making recommendations about keeping pets for asthma prevention. Families with existing pet dogs may find reassurance in the findings, but decisions around pets should consider broader health, lifestyle, and environmental factors.
The study offers new insight into how early-life exposure to household allergens can shape long-term respiratory health. Dog allergens appear to provide a protective effect against childhood asthma, while cat allergens do not show the same benefit. Further research is required to confirm the mechanisms involved and to explore how this knowledge might inform asthma prevention strategies in the future.