Secondhand smoke and e-cigarette aerosol exposure in dogs and cats: A scoping review with implications for smoking cessation among pet owners

Introduction: The harmful effects of secondhand smoke (SHS) on human health are well established, whereas its impact on pets remains underexplored and less widely recognized by both the scientific community and the general public. This scoping review aimed to synthesize current evidence on the health effects of SHS and electronic cigarette (e-cigarette) aerosol exposure in dogs and cats. Methods: An in-depth PubMed search was conducted using predefined keywords, limited to free full texts in English with available abstracts and relevance to the topic. Results: Twenty-six eligible articles were analyzed. Of the 11 studies investigating cancers, respiratory, and cardiovascular diseases in dogs and cats, over half reported statistically significant associations with SHS. Biomarkers such as cotinine were identified in serum, urine, fur, and amniotic fluid, confirming that pets are not only passive recipients of human environmental exposures but may also serve as environmental sentinels within a One Health framework. No eligible studies addressed e-cigarette aerosol in pets, but human data indicate potential risks. Notably, awareness of SHS risks to pets may motivate owners to adopt smoke-free behaviors. Conclusions: Despite some inconsistencies, available evidence supports the harmful effects of SHS in pets. Veterinary and public health professionals can leverage these findings to raise awareness and promote smoking cessation, integrating pet welfare into tobacco control strategies. Further studies are needed to standardize exposure assessment and evaluate long-term health effects.