Association between indoor air pollution and respiratory disease in companion dogs and cats

BACKGROUND: Indoor air pollution (IAP) leads to important respiratory morbidity and mortality in humans. Companion dogs and cats share the same household environment with their owners and are exposed to IAP. HYPOTHESIS: Pets with respiratory disease are more commonly exposed to indoor air pollutants in their homes and to worse air quality than pets without respiratory disease. ANIMALS: Three hundred and forty‐eight animals (230 dogs and 118 cats) were recruited. METHODS: Dogs and cats attending the National Taiwan University Veterinary Hospital were prospectively enrolled over a 12‐month period. Questionnaires were collected from pet owners regarding the status of signs of respiratory problem of animals and air pollutants in their homes. Clinical assessment was performed by veterinarians on all animals included in the case‐control study and the presence/absence of respiratory disease and diagnoses were recorded. Individual exposure to particulate matter of 2.5 μm or less (PM2.5) was estimated in the domestic microenvironment of the animals. RESULTS: Dogs with respiratory disease were more commonly exposed to incense burning than control dogs (30 versus 13%, P = .045), but household PM2.5 level was not different between dogs with and without respiratory disease [median 30.8 μg/m³, range 10.8‐214.2 versus median 38.2 μg/m³, range 5.4‐69.4, P = .57]. Signalment factors (age, body weight, and body condition score) instead of IAP factors were associated with respiratory disease in dogs using multivariable logistic regression. In contrast, household PM2.5 level was significantly higher in cats with respiratory disease than in control cats [median 38.6 μg/m³, range 17.8‐131.2 versus median 27.4 μg/m³, range 15.4‐70.0, P = .017]. Cats living in households with PM2.5 > 35 μg/m³ were more likely to have respiratory disease than those living in households with acceptable levels of PM2.5 (OR = 4.13, 95% CI 1.12‐15.27, P = .03). CONCLUSIONS AND CLINICAL IMPORTANCE: The link between IAP and respiratory disease in dogs is complicated. An unacceptable level of household PM2.5 (>35 μg/m³) is significantly associated with respiratory disease in cats. The effect of IAP on the respiratory health of companion animals warrants further attention.