TOPLINE:

Continuous household dog exposure in children with asthma and airway allergy is associated with a 1.2-fold higher risk for asthma exacerbations but does not increase the risk for moderate-to-severe asthma over 6 years. Among 99,389 Swedish children aged 3-16 years, those with continuous dog exposure had more emergency visits and higher short-acting beta-2 agonist (SABA) use than nonexposed children, yet asthma severity remained similar across exposure groups.

METHODOLOGY:

• Researchers conducted a nationwide cohort study in Sweden using national health registers, following 99,389 children aged 3-16 years who met validated criteria for both asthma and airway allergy as a proxy for allergic asthma.
• Participants were followed from 1 year after diagnosis until age 19 years, emigration, death, or December 2023, with a median follow-up of 6.0 years; dog exposure was categorized as continuous (parental dog ownership at diagnosis and throughout follow-up), discontinued (ownership ceased after diagnosis), or no exposure.
• Primary outcomes included moderate-to-severe asthma assessed at 2-, 4-, and 6-year follow-up based on dispensed asthma medications using adapted Global Initiative for Asthma treatment steps, as well as asthma exacerbation measured by emergency visits and high SABA use (more than five dispensed prescriptions per year) throughout follow-up.
• Analysis utilized logistic regression for moderate-to-severe asthma outcomes, Cox-based shared-frailty models for recurrent emergency visits, and generalized estimating equations for longitudinal high SABA use, with adjustments for sex, age, baseline asthma severity, population density, parental asthma, parental education, and parental country of birth.
• Data sources included the Swedish National Patient Register for diagnoses, the Prescribed Drug Register for medications, the National Dog Register and Swedish Kennel Club Dog Register for dog ownership, and the Total Population Register for demographic information.

TAKEAWAY:

• Continuous dog exposure showed no significant association with moderate-to-severe asthma at 2-year follow-up after adjustment (adjusted odds ratio [OR], 1.00; 95% CI, 0.94-1.07; P = .326), and similarly at 4- and 6-year follow-up.
• Children with continuous dog exposure had a significantly increased risk for emergency asthma visits compared with nonexposed children (adjusted hazard ratio, 1.17; 95% CI, 1.06-1.29; P = .002), with an incidence rate of 15.1 per 1000 person-years vs 14.6 per 1000 person-years in the nonexposed group.
• Continuous dog exposure was associated with 1.25 times higher odds of high SABA use over the follow-up period than nonexposed children (adjusted OR, 1.25; 95% CI, 1.12-1.39; P < .001).
• Discontinued dog exposure showed similar asthma outcomes to continuous exposure, with no significant differences between the two groups in terms of moderate-to-severe asthma or exacerbation risk, suggesting that discontinuing dog ownership does not appear to improve asthma outcomes at the population level.

IN PRACTICE:

“The asthma outcomes do not differ between children with continuous and discontinued dog exposure. These findings suggest that keeping a dog in households with children who have asthma and allergy may not affect overall asthma severity but could trigger exacerbations,” the authors of the study wrote.

SOURCE:

The study was led by Resthie R. Putri, PhD, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden. It was published online in Journal of Allergy and Clinical Immunology: Global.

LIMITATIONS:

According to the authors, data on dog allergen sensitization and specific asthma phenotypes were not available, although prior studies suggest the association between dog exposure and pediatric asthma outcomes does not differ by dog-specific sensitization. Parental dog ownership may not fully capture the duration and intensity of exposure, and for children with divorced parents, accurately tracking continuous household dog exposure becomes challenging, increasing the potential for misclassification bias. Information on other pet exposure and whether dogs were kept indoors or outdoors was unavailable, though most dogs in Sweden typically reside indoors with their owners. The generalizability of these findings to other populations may be affected by variations in cultural practices related to dog ownership, the prevalence of dog ownership, and outdoor and indoor environmental factors such as climate and wall and floor materials.

DISCLOSURES:

This research received support from the Swedish Research Council (grant number 2023-02327), the Swedish Heart-Lung Foundation (grant number 20240974), the Swedish Asthma and Allergy Association Research Fund (grant number 2024-0010), grants provided by Region Stockholm (ALF project RS2022-0674), the Strategic Research Program in Epidemiology at Karolinska Institutet, and the Foundation Frimurare Barnhuset in Stockholm. The funder had no role in the design, data collection, data analysis, and reporting of this study. None of the authors disclosed having any conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.