Exposure to cats and dogs as risk factors for wheezing in preschool children: are their effects modified by removal?

Abstract

Objective: To define the relationship between current wheezing in preschoolers and exposure to dogs and cats at home, and to find out to what extent their removal modifies the associations.

Methods: Previously validated questionnaires were completed by parents of 1784 preschoolers (mean age 4.08±0.8 years). Children were stratified according to the presence (20.0 %) or absence of wheezing in the previous year. Information regarding cat or dog exposure currently and during the first year of life was collected, as well as information about the removal of the pets.

Results: A higher proportion of families owning a cat in the first year of the child’s life, as well as in the previous year, was found in the wheezing group. The proportion of families owning a dog was marginally higher in this group. Cat exposure was shown to be a significant risk factor when present in the first year of the child’s life (Adjusted Odds Ratio [aOR] 1.73, 95 % CI 1.04-2.88), and an even higher association was found with current exposure (aOR 2.00, 95 % CI 1.22-3.26). The association was highest (aOR 2.68, 95 % CI 1.32-5.44) among the wheezing group for the subset of families that had removed a cat from the home. Dog exposure did not appear to be a significant risk factor, neither during the first year of life (aOR 1.24, 95 % CI 0.88-1.76) nor with current ownership (aOR 1.04, 95 % CI 0.73-1.50). However, a significant association was found in the group that had removed a dog from the home (aOR 5.88, 95 % CI 2.62-13.17).

Conclusions: Exposure to cat allergens is a risk factor for asthma, when exposure occurs during the first 12 months of life. However, this factor is of limited influence beyond the first year. It is likely that children who are prone to developing an allergy would benefit from control of environmental allergen exposure, including cat avoidance.