Background: Currently, there is a lack of consensus regarding the infl uence of household pets on the development of allergic diseases in childhood.

Objective: The aim of this birth cohort study was to analyze the relationship between pet ownership at time of birth and the prevalence of atopic diseases approximately 2 years later.

Methods: A few days after the delivery of their babies, we asked 3132 mothers of German nationality whether they kept household pets like dogs, cats, or birds. Two years later, we asked whether their children had developed bronchial asthma, eczema, or hay fever. We then used logistic regression models to analyze whether there was an association between the development of allergic reactions among the children and pet ownership at the time of birth.

Results: In families without a history of atopic disease, the prevalence of asthma and eczema among 2-year-old children was significantly lower in those families that owned a dog at the time the children were born (odds ratio [OR], 0.52; 95% confi dence interval [CI], 0.33-0.83). In contrast, in families with a history of atopic disease, early dog exposure was associated with a higher prevalence of asthma and eczema in 2-year-old children (OR, 1.43; 95% CI, 0.95-2.15). Comparable analyses assessing the infl uence of cats and birds in the home showed no effect on the development of atopic diseases in early childhood.

Conclusions: This study confi rms the fi ndings of several earlier studies suggesting a negative association between dog ownership and the development of atopic diseases in early childhood, although the effect was only observed in families without a history of atopic disorders.

Key words: Allergies. Children. Epidemiology. Pets.