Pets in lower-income households face much higher secondhand smoke exposure, study finds

Pets living in lower-income neighborhoods are exposed to secondhand smoke (SHS) at markedly higher rates than pets in wealthier communities, according to a new study published in the Journal of Shelter Medicine and Community Animal Health.¹ Researchers from the Cummings School of Veterinary Medicine at Tufts University tested urine samples from dogs, cats, and 1 rabbit for cotinine, a stable byproduct of nicotine metabolism and a recognized marker of tobacco smoke exposure.

Key findings

Investigators collected 168 leftover urine samples submitted for routine testing from patients at 4 Massachusetts communities selected to represent a range of socioeconomic status (SES): a low-income, income-screened community clinic in Worcester, and 3 referral hospital populations in progressively higher-income towns—Webster/West Brookfield, Walpole/Westboro, and Wellesley/Weston. Median household incomes in these areas ranged from about $31,000 in the low-income group to $250,000 in the highest-income group, based on 2024 US Census Bureau data.¹

Each sample was tested with a point-of-care lateral flow immunoassay for urinary cotinine, with a positive cutoff of 5 mg/mL. Results were analyzed using logistic regression, with low-income towns as the reference group.

Of the 168 samples, 17 (10.1%) tested positive for cotinine overall, which is a rate the authors note is comparable to the adult smoking rate in Massachusetts generally. But the distribution across income groups was stark: the low-income community had a 26.7% exposure rate, compared with 12.1% in the lower-middle-income town, 1.3% in the upper-middle-income town, and 0% in the highest-income community.¹

Pets in middle- to high-income towns had significantly lower odds of testing positive for cotinine compared with those in the low-income town, and the difference for the lower-middle-income group did not reach statistical significance. Cats in the low-income group had a notably high exposure rate of 66.7%, though the authors caution that small subgroup sizes limit the strength of that finding.¹

Why it matters

SHS exposure is a well-established human health risk, linked to respiratory disease, cardiovascular disease, and certain cancers, with lower-SES populations bearing a disproportionate burden due to higher baseline smoking rates.^2,3 Emerging veterinary literature suggests companion animals may carry similar risks. Dogs with long noses have shown an increased risk of nasal cancer with SHS exposure, and cats exposed to environmental tobacco smoke have shown higher rates of oral squamous cell carcinoma.^4,5

The authors argue that documenting a pet's SHS exposure creates a natural opening for veterinary teams to discuss smoking cessation with clients, potentially benefiting both the pet and the humans in the household, including children. Prior survey data suggest as many as half of pet owners would consider reducing their pet's smoke exposure if made aware of the risks.⁶

However, the study authors note several caveats, including that samples were drawn from a small number of Massachusetts towns with an already low baseline smoking rate, cotinine's short half-life means spot urine testing captures only recent exposure, and SES was assigned by ZIP code rather than individual household data. The point-of-care assay used has been validated in humans but not specifically in companion animal species.¹

Still, the authors conclude that community veterinary practices are well-positioned to screen for SHS exposure and use the results to start non-judgmental conversations about smoking cessation resources, particularly in underserved populations where both human and animal health may benefit.

References

1. Smith N, Rozanski E. Pets in lower socioeconomic communities have a higher exposure to second-hand smoke. J Shelter Med Community Anim Health. 2026;5(1). doi:10.56771/jsmcah.v5.151
2. Flor LS, Anderson JA, Ahmad N, et al. Health effects associated with exposure to secondhand smoke: a Burden of Proof study. Nat Med. 2024;30(1):149-167. doi:10.1038/s41591-023-02743-4
3. Garrett BE, Martell BN, Caraballo RS, King BA. Socioeconomic differences in cigarette smoking among sociodemographic groups. Prev Chronic Dis. 2019;16:180553. doi:10.5888/pcd16.180553
4. Reif JS, Bruns C, Lower KS. Cancer of the nasal cavity and paranasal sinuses and exposure to environmental tobacco smoke in pet dogs. Am J Epidemiol. 1998;147(5):488-492. doi:10.1093/oxfordjournals.aje.a009475
5. Zaccone R, Renzi A, Chalfon C, et al. Environmental risk factors for the development of oral squamous cell carcinoma in cats. J Vet Intern Med. 2022;36(4):1398-1408. doi:10.1111/jvim.16372
6. Milberger SM, Davis RM, Holm AL. Pet owners' attitudes and behaviours related to smoking and second-hand smoke: a pilot study. Tob Control. 2009;18(2):156-158. doi:10.1136/tc.2008.028282