Background: In the treatment of bronchial asthma, the identification, isolation, and elimination of causative allergens is the most effective part of treatment. With the recent diversification within the pet industry, pet owner exposure to many unknown antigens is on the rise. The results of population studies have been contradictory and some epidemiological studies have failed to confirm this, some indicating that keeping pets might actually reduce the risk of sensitization and asthma. The purpose of this study was to determine the association between pet ownership and asthma.

Methods: This case-control study included 300 asthmatic participants referred to the Children's Medical Center over a two-year period. Participants were asked to fill out a questionnaire regarding pet ownership, pet gender and puberty, the place it was kept, how long the pet was kept and the reason for keeping the pet. The same questions were asked from 300 age- and gender-matched nonasthmatic individuals as the control group. Statistical analysis was performed to calculate odds ratios (OR) of asthma morbidity in individuals who kept pets.

Results: The OR for asthma morbidity in patients who kept pets was 2.59 (CI=1.60-4.21 and p>0.001). Financial aim was the most common reason for keeping a pet and most pets were mature and kept outdoors. No significant correlations for pet genders were observed.

Conclusion: This survey provides evidence that pet ownership is an important risk factor for asthma, therefore we suggest that individuals at risk for asthma (atopic individuals) must avoid contact with pets. However, more research in this field in Iran is necessary.