Overview

• Researchers from The Hospital for Sick Children analyzed dust from the homes of 1,050 infants at three to four months of age and followed them to age five for asthma diagnosis and lung function testing.
• Higher levels of the dog allergen Can f1 in early household dust were associated with about a 48% lower risk of doctor-diagnosed asthma at age five.
• Children with greater early exposure to dog allergen also showed higher FEV1 at age five, with stronger associations in those at higher genetic risk of poorer lung function.
• No protective association was observed for the cat allergen Fel d1 or for bacterial endotoxin measured in the same early-life dust samples.
• Authors and external experts stressed that mechanisms remain uncertain and said the findings should not yet guide clinical advice or decisions about keeping pets.