Asthma, Rhinitis, Other Respiratory Diseases
Dog exposure in infancy decreases the subsequent risk of frequent wheeze but not of atopy,☆☆

https://doi.org/10.1067/mai.2001.117797Get rights and content

Abstract

Background: Influence of household pets in the development of childhood asthma or atopy has been controversial. Objective: The purpose of this study was to investigate whether pet exposure in early life decreases the subsequent risk of frequent wheezing and/or allergic sensitization. Methods: This was a prospective observational birth cohort study. The setting was a large health maintenance organization in Tucson, Ariz; the subjects were a population sample of 1246 newborns enrolled at birth and followed prospectively to age 13 years. The main outcome measures were as follows: time to first report of frequent wheezing (>3 episodes in the past year), skin prick test reactivity at 6 years and 11 years of age, and total serum IgE at 9 months, 6 years, and 11 years of age. Results: Children living in households with ≥1 indoor dogs at birth were less likely to develop frequent wheeze than those not having indoor dogs (P = .004). This inverse association was confined to children without parental asthma (hazard ratio = 0.47; P < .001 [Cox regression]) and was not evident for children with parental asthma (hazard ratio = 0.96; P = .87). Adjustment by potential confounders did not change the results. Indoor cat exposure was not significantly associated with the risk of frequent wheezing. Neither cat exposure in early life nor dog exposure in early life was associated with skin prick test reactivity or total serum IgE at any age. Conclusion: Dog exposure in early life might prevent the development of asthmalike symptoms, at least in low-risk children with no family history of asthma. Nevertheless, early pet exposure does not seem to significantly influence the development of allergic sensitization. (J Allergy Clin Immunol 2001;108:509-15.)

Section snippets

Methods

A cohort of 1246 healthy babies were enrolled at birth in the Tucson Children's Respiratory Study between 1980 and 1984.8 Information regarding household pets was collected at enrollment (ie, soon after the baby was born). Similarly, data on potential confounders (defined below) were obtained from parents by questionnaire at enrollment; maternal smoking in infancy was ascertained when the children were 2 years old. Follow-up questionnaires asking about respiratory symptoms were completed by the

Characteristics of the study population

The original cohort included 1246 subjects, 14 (1%) of whom were missing data on early pet exposure. Enrollment questionnaires were completed at a median age of 2 weeks; >95% of the questionnaires were completed in the first month of life. Data regarding frequent wheeze were available on 1076 children (86%). Skin prick test data were available for 737 and 613 children at 6 years and 11 years, respectively, and total serum IgE data for 829, 534, and 462 subjects at 9 months, 6 years, and 11

Discussion

The major finding of the present study is that exposure to dogs in early life might be protective against the subsequent development of frequent wheezing. This was especially evident among children with no parental history of asthma. The lack of a relation between exposure to dogs and the development of asthma in children with parental history of asthma could reflect the fact that asthmatic parents avoid this exposure. Alternatively, any protective effect of exposure to dogs might be

Acknowledgements

We thank Bruce W. Saul, MSc, for his assistance in data management issues, and the study nurses, M. A. Smith Lindell, RN, and L. L. De La Ossa, RN, for their work.

References (30)

  • B Hesselmar et al.

    Does early exposure to cat or dog protect against later allergy development?

    Clin Exp Allergy

    (1999)
  • LM Taussig et al.

    The Tucson Children's Respiratory Study, I. Design and implementation of a prospective study of acute and chronic respiratory illness in children

    Am J Epidemiol

    (1989)
  • M Halonen et al.

    Alternaria as a major allergen for asthma in children raised in a desert environment

    Am J Respir Crit Care Med

    (1997)
  • M Halonen et al.

    Relationship of total serum IgE levels in cord and 9-month sera of infants

    Clin Exp Allergy

    (1991)
  • StataCorp

    Stata Statistical Software. Release 6.0

    (1999)
  • Cited by (0)

    The Children's Respiratory Study was funded through NHLBI SCOR grants #HL 14136 and #HL 56177. This work was conducted during the stay of S. T. Remes in Tucson with funding from the Academy of Finland, the Finnish Medical Foundation, and the Finnish Pediatric Research Foundation.

    ☆☆

    Reprint requests: Anne L. Wright, PhD, Respiratory Sciences Center, 1501 N. Campbell Ave, Tucson, AZ 85724.

    View full text