Purpose of the Study. To study the relationship between early pet exposure and the risk of developing atopic disease in the first 4 years of life.
Study Population. The study comprised a birth cohort of 3754 children born in Oslo during a 15-month period in 1992–1993. Over the 4-year period of the study, participants were excluded because of incomplete information or failure to be reached by mail during the follow-up period. The final analysis included 2531 children from the birth cohort.
Methods. The cohort was followed mainly by questionnaire to provide information about early life exposure to pets, child/family characteristics, environmental exposures, and atopy-related diseases. Questionnaires were administered at birth, 6, 12, 18, and 24 months, and a follow-up questionnaire was administered at 4 years. A subset (n = 502) of participants was studied in a matched case-control analysis of early environmental exposure and the risk of bronchial obstruction. These participants received home visits to assess environmental exposure and collection of dust samples for common aeroallergens. The information obtained from home visits was used to estimate agreement between questionnaire data on the presence of pets and allergen concentration in the dust samples. During the first 2 years of life, bronchial obstruction was defined as 2 or more episodes of obstruction or 1 episode lasting >1 month. Information on current asthma or allergic rhinitis was derived from the follow-up questionnaire and was based on a physician’s diagnosis during the previous 12 months. A history of eczema was taken from the 6-month questionnaire.
Results. This study found that there was a positive relationship between dog exposure at birth and bronchial obstruction during the first 2 years of life, although no association was noted at 4 years of age. There was a negative relationship (odds ratio = 0.6) between pet exposure and allergic rhinitis if a pet was present at birth. Additionally, the risk of having both asthma and allergic rhinitis (n = 44) was higher in unexposed children as compared with exposed children (0.023 and 0.006, respectively). Eczema was also less common during the first 6 months of life among the exposed population.
Conclusion. Although bronchial obstruction during the first 2 years of life was more common in dog owners, there was a negative relationship between pet ownership and atopy-related disease at 4 years of life.
Reviewers’ Comments. Information about the effects of pet ownership in childhood is controversial. Many previous studies have found a positive relationship between pet ownership and allergic disease, leading to the widely accepted recommendation of refraining or removal of pets from the home. The current study, as well as others, found that pet ownership may have a protective effect against the development of allergic disease. Children who were exposed to pets at birth had a lower prevalence of allergic rhinitis, asthma, and infant eczema, although this study did not account for those families who did not own pets because of a family history of atopy. This would lead to selection bias because those families without a history of atopy would be more likely to own pets. Also, the number of participants with pet exposure was low (22%), and results may differ in a population with a higher prevalence of pet ownership.
- Copyright © 2002 by the American Academy of Pediatrics