Pet-keeping and its impact on asthma and allergies among preschool children in Shanghai, China

Whether early pet-keeping is a risk factor for children's asthma and allergies remains controversial. To investigate associations between asthma, allergies and airway symptoms among children and the indoor environment, a cross-sectional study was conducted in 5 districts of Shanghai. A number of 13335 questionnaires (response rate: 85.3%) of 4-6 year old children were analyzed. Families in urban areas have more pets except for dogs than families in suburbs. Fish are the most common pets in urban districts. The prevalence of doctor-diagnosed asthma was 10.3%, wheeze (ever) 28.3%, rhinitis (ever) 54.1%, doctor-diagnosed hay fever 12.6% and eczema (ever) 22.9%. In logistic regression analyses, early furred pet-keeping was positively associated with most of the symptoms and significantly with rhinitis (ever, adjusted OR=1.41, 95% CI=1.14-1.76) and doctor-diagnosed hay fever (1.38, 1.02-1.88). Current furred pet-keeping was significantly negatively associated with doctor-diagnosed asthma (0.57, 0.39-0.83). Persistent furred pet-keeping was significantly positively associated with rhinitis on pet or pollen exposure. However, current pet-keeping is not randomly distributed in the population. Children in families with "allergy" or with "pet avoidance behavior" (due to allergies in the family) have more symptoms, but have avoided cats and dogs, leading to the conclusion that such animals are "protective", namely the "Healthy Pet-Keeping" effect. Moreover, rodents and birds are risks for children's health. Fish-keeping is also seemingly a risk. This study indicates that early pet-keeping is a risk factor for asthma and allergies in families with a history of allergies, and part of residents in Shanghai have pet-avoidance behavior.