Exposure to dogs but not cats is associated to a decrease in the prevalence in atopic dermatitis amongst school-children.

INTRODUCTION: The association regarding the exposure to pets, especially cats and dogs, and the prevalence of allergic diseases is inconsistent.

OBJECTIVE: We analyzed the role played by early exposure to dogs or cats in the prevalence of allergic diseases amongst school-aged children.

METHOD: Through a cross-sectional study, we examined 756 children, aged 6-7; these candidates were selected through cluster sampling. We inquired about the exposure that these children had had to dogs and cats, and whether these pets spent most of their time indoors or outdoors during the first year of the child's life. In order to identify the prevalence of allergic diseases and their symptoms, each child's parent completed the International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS: Exposure to outdoor dogs was associated to nocturnal coughing, odds ratio (OR) 0.64, with a confidence interval of 95% (95% CI) 0.43-0.95 and with atopic dermatitis (OR: 0.39; 95% CI: 0.20-0.76). Interestingly, exposure to outdoor cats was associated to nocturnal coughing (OR: 0.51; 95% CI: 0.32-0.83) and current rhinitis symptoms (OR: 0.59; 95% CI 0.36-0.97). After carrying out the multivariate analyses, only exposure to dogs, both indoor and outdoor, was significantly associated to a decrease in the prevalence of atopic dermatitis OR 0.40 (95% CI: 0.20-0.79) and OR 0.38 (95% CI: 0.18-0.83), respectively.

CONCLUSION: Our findings suggest that exposure to dogs, whether they be indoor or outdoor pets, is associated to a decreased prevalence in atopic dermatitis.