The relationship between pet ownership and various health outcomes, including physical activity, mental health, and atopy, is complex and inconsistently reported across studies from Western and East Asian contexts. While some studies suggest a positive association between pet ownership, particularly dog ownership, and increased physical activity due to activities like walking, the impact on mental health is debated. Some research suggests improved mental well-being through stress reduction and increased social interaction, while others report potential negative effects due to the demands of pet ownership. Similarly, the effect of pet ownership on atopic conditions (asthma, allergic rhinitis, and eczema) is unclear, with some studies suggesting protective effects and others indicating potential exacerbation of symptoms. Given the absence of research on this topic in Southeast Asia, particularly Singapore, this study aimed to explore these associations within a Singaporean adult population, considering various demographic and pet-related factors to understand the nuances of pet ownership's impact.

Existing literature presents conflicting evidence regarding the impact of pet ownership on human health. A review of studies by the American Heart Association acknowledged the positive effects of pet ownership (specifically dog ownership) on physical activity levels. Evidence also supports the cumulative effects of pet ownership throughout a person's lifetime, with greater benefits observed in older age. However, the effect on mental health is controversial, with some studies reporting improved mental well-being due to increased social interaction and stress reduction, while others suggest a potential negative association. The influence of pet ownership on atopic conditions is also debated. Some research suggests protection against atopic conditions through allergen desensitization, while others suggest pets contribute to higher rates of atopic conditions due to allergens.

This cross-sectional study utilized a self-administered online questionnaire to survey 823 adults aged 21-64 in Singapore. Participants with physical disabilities requiring assistance with activities of daily living or owning therapy/guide dogs were excluded. Recruitment occurred through various channels, including veterinary clinics, online messaging applications, social media, and email. The questionnaire collected data on sociodemographics, medical history, pet ownership (current and past), pet attachment, physical activity levels (categorized by intensity), general and mental health (using the SF-36 questionnaire), and atopic conditions. To minimize confounding, propensity score matching (PSM) was employed using logistic regression to create a balanced subset of 566 participants (283 pet owners and 283 non-pet owners). Statistical analyses included Mann-Whitney U tests, Pearson's χ² tests, Poisson regression, Wilcoxon signed-rank tests, McNemar's χ² tests, and mixed-effects models, depending on the variable type. Subgroup analyses examined potential effect modifiers like age, race, marital status, and caregiver role.

No significant differences in overall physical activity levels (mild, moderate, or vigorous) or mental health scores (SF-36 subscales) were found between pet owners and non-pet owners in the propensity score-matched cohort. However, subgroup analyses revealed significant associations. Main pet caregivers reported significantly more minutes per week of moderate- and vigorous-intensity physical activity (14.1 and 19 minutes respectively) and higher SF-36 emotional well-being and energy scores. Age acted as an effect modifier; older pet owners (above ages 39, 35, and 39 for emotional well-being, energy, and social functioning respectively) had significantly higher scores than their matched non-pet owner counterparts. Regarding atopy, pet acquisition was associated with worsening allergic rhinitis, while pet ownership cessation was linked to improvements in allergic rhinitis and eczema symptoms. Specific pet types (dogs, cats, birds) also showed different associations with physical activity and mental health.

The findings highlight the complexities of the relationship between pet ownership and health outcomes. While no overall differences were found between pet owners and non-pet owners in the propensity-score matched cohort, subgroup analyses revealed important nuances. The increased physical activity among main pet caregivers suggests that active engagement with pets is crucial for reaping the physical activity benefits. The age-dependent effect modification for mental health suggests that the benefits of pet ownership may be more pronounced in older adults. The association between pet ownership and atopy underscores the importance of considering potential allergen exposure. These findings contribute to a more comprehensive understanding of the impact of pet ownership by emphasizing the need to consider various factors, including the type of pet, the level of caregiver involvement, and age.

This study, the first of its kind in Southeast Asia, provides valuable insights into the association between pet ownership and physical activity, mental health, and atopy in a Singaporean adult population. While overall effects were not significant, subgroup analyses revealed crucial associations between active pet caregiving, age, and specific pet types with physical activity and mental health. Further research should explore the long-term effects of pet ownership across different age groups and investigate the immunological mechanisms underlying the relationship between pet ownership and atopy.

The study's limitations include the cross-sectional design, which limits causal inference, and the reliance on self-reported data, which may be subject to recall bias. The online survey methodology may have resulted in a skewed sample, with a higher proportion of younger adults compared to the general Singaporean population, potentially affecting the generalizability of findings. The exclusion of individuals aged 65 and above could have limited the assessment of pet ownership's benefits in older adults. Multiple testing was acknowledged as a potential source of type I error. Despite the propensity score matching, the study still relies on a voluntary online survey which can introduce selection bias