title: Pet-keeping in childhood and adult asthma and hay fever: European community respiratory health survey.
abstract: BACKGROUND
  Whether pet-keeping early in life protects against or promotes allergy remains unclear.
  
  
  OBJECTIVE
  Our aim was to examine the effects of childhood pet-keeping on adult allergic disease in a large international population-based study, including information on sensitization, adult pet-keeping, and pet prevalence in the populations.
  
  
  METHODS
  We used information from structured interviews (n = 18,530) and specific IgE to common aeroallergens in blood samples (n = 13,932) from participants in the European Community Respiratory Health Survey (ECRHS) to analyze the associations between keeping pets and adult asthma and hay fever.
  
  
  RESULTS
  Keeping cats in childhood was associated with asthma only among atopic subjects, an association that varied between centers (P =.002) and was stronger where cats where less common (< 40% cats: odds ratio(wheeze) [OR(wheeze)] = 1.84, 95% CI = 1.31-2.57; 40%-60% cats: OR(wheeze) = 1.33, 95% CI = 1.10-1.61; > or =60% cats: OR(wheeze) = 0.98, 95% CI = 0.73-1.33). Dogs owned in childhood or adulthood were associated with asthma among nonatopic subjects (childhood: OR(wheeze) = 1.28, 95% CI = 1.13-1.46; adulthood: OR(wheeze) = 1.31, 95% CI = 1.14-1.51; both: OR(wheeze) = 1.69, 95% CI = 1.40-2.04). In atopic subjects, those who had owned dogs in childhood had less hay fever (OR = 0.85; 95% CI = 0.73-0.98) and no increased risk of asthma (OR(wheeze) = 1.01, 95% CI = 0.87-1.17). Respiratory symptoms were more common in subjects who had owned birds during childhood (OR(wheeze) = 1.12; 95% CI = 1.02-1.23) independent of sensitization.
  
  
  CONCLUSIONS
  The effects of pet-keeping in childhood varied according to the type of pet, the allergic sensitization of the individual, and the wider environmental exposure to allergen. Cats owned in childhood were associated with more asthma in sensitized adults who grew up in areas with a low community prevalence of cats. Dogs owned in childhood seemed to protect against adult allergic disease but promote nonallergic asthma.
authors.affiliation: Section of Respiratory Medicine, Institute of Medicine, University of Bergen and Department of Medicine, Haraldsplass Hospital, Bergen, Norway.
authors.forename: Cecilie
authors.initials: C
authors.lastname: Svanes
authors.forename: Joachim
authors.initials: J
authors.lastname: Heinrich
authors.forename: Deborah
authors.initials: D
authors.lastname: Jarvis
authors.forename: Susan
authors.initials: S
authors.lastname: Chinn
authors.forename: Ernst
authors.initials: E
authors.lastname: Omenaas
authors.forename: Amund
authors.initials: A
authors.lastname: Gulsvik
authors.forename: Nino
authors.initials: N
authors.lastname: Künzli
authors.forename: Peter
authors.initials: P
authors.lastname: Burney
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000829:Animals, Domestic; D001249:Asthma / Q000276:immunology* / Q000517:prevention & control; D001717:Birds / Q000276:immunology; D002415:Cats / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D004285:Dogs / Q000276:immunology; D004781:Environmental Exposure; D005260:Female; D006306:Health Surveys; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D007391:International Cooperation; D008297:Male; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology* / Q000517:prevention & control