Several studies have demonstrated an association between secondhand smoke exposure and negative health effects in animals that are similar to the health effects seen in humans. These include several cancers including lung cancer and cancer of the nasal cavity and paranasal sinuses in dogs,1-3 and lymphoma in cats.4 There is limited evidence that secondhand smoke exposure may also lead to other diseases including eye disease, respiratory problems and skin disease.5
Urinary and hair cotinine levels in pet dogs is strongly associated with the number of cigarettes reported by owners to have been smoked in the household.6,7 Dogs and cats may be exposed to smoke through inhalation of airborne secondhand smoke as well as transdermal absorption and oral ingestion of thirdhand smoke. Cats may be particularly susceptible to the latter because of their oral grooming behaviours.
There is some evidence that different breeds of dogs are more susceptible to particular health effects of secondhand smoke exposure. Long-nosed dogs appear to be more likely to develop nasal cancer, likely due to secondhand smoke components remaining in the nose. In contrast, short-nosed dogs are more prone to cancer, likely due to more secondhand smoke reaching the lungs after inhalation.2,3
4.20.1 Smokers’ knowledge of pet harm from secondhand smoke exposure and intention to quit
Awareness of pet harms from secondhand smoke exposure may be a motivating factor for smokers to attempt to quit smoking. A survey of pet owners found that information on the dangers of pet exposure to secondhand smoke would motivate 28% of smokers to try to quit and 19% to not allow smoking inside their home.5 The same survey found that among non-smoking pet owners who lived with smokers, given the same information about pet harms from secondhand smoke exposure, 16% would ask those they live with to quit smoking and 24% would ask the people they live with to not smoke indoors.
Relevant news and research
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1. Perez N, Berrio A, Jaramillo JE, Urrego R, and Arias MP. Exposure to cigarette smoke causes DNA damange in oropharyngeal tissue in dogs. Mutation Research/Genetic Toxicoloogy and Environmental Mutagenesis, 2014; 769:13–9. Available from: http://www.sciencedirect.com/science/article/pii/S1383571814001193
2. Reif JS, Bruns C, and Lower KS. Cancer of the nasal cavity and paranasal sinuses and exposure to environmental tobacco smoke in pet dogs. American Journal of Epidemiology, 1998; 147(5):488–92. Available from: https://www.ncbi.nlm.nih.gov/pubmed/9525536
3. Reif JS, Dunn K, Ogilvie GK, and Harris CK. Passive smoking and canine lung cancer risk. American Journal of Epidemiology, 1992; 135(3):234–9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/1546698
4. Bertone ER, Snyder LA, and Moore AS. Environmental tobacco smoke and risk of malignant lymphoma in pet cats. American Journal of Epidemiology, 2002; 156(3):268 –73. Available from: https://www.ncbi.nlm.nih.gov/pubmed/12142262
5. Milberger SM, Davis RM, and Holm AL. Pet owners' attitudes and behaviours related to smoking and second-hand smoke: A pilot study. Tobacco Control, 2009; 18(2). Available from: http://tobaccocontrol.bmj.com/content/18/2/156
6. Bertone-Johnson ER, Proctor-Gray E, Gollenber AL, Bundga ME, and Barber LG. Environmental tobacco smoke and canine urinary cotinine level. Environmental Research, 2008; 106(3):361–4. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2297465/
7. Knottenbelt CM, Bawazeer S, Hammond J, Mellor D, and Watson DG. Nicotine hair concentrations in dogs exposed to environmental tobacco smoke: A pilot study. Journal of Small Animal Practice, 2012; 53(11):623–6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23020087