Large Swedish study challenges long-held concerns that pet cats aggravate childhood asthma and allergy symptoms.
To borrow from The Clash (and slightly abuse the original lyrics): should the cat stay or should it go?
The family feline may have previously been wrongly accused of worsening asthma symptoms, asthma attacks, lung function, or overall asthma control in children, but researchers now believe swift acquittal is in order.
In one of the largest studies ever conducted on the topic, they found no evidence to support these previous charges against the species.
Swedish researchers followed 30,277 children born between 2006 and 2020 who had established diagnoses of asthma and airway allergies. Using linked data from several national databases, including Sweden’s National Cat Register (mandatory for pet cats born after 2008), diagnoses, prescriptions, emergency visits, lung function testing, and cat ownership were all evaluated.
Fewer than one in 10 children lived in a household with at least one cat and, during a two-year observation period spanning 2023 and 2024, there was remarkably little difference in asthma outcomes between kids who did and didn’t.
Moderate-to-severe asthma occurred in 9.6% of children exposed to cats, compared with 10.1% of children who did not live with cats.
After accounting for factors such as age, sex, parental asthma history, allergy history, socioeconomic status, and baseline disease severity, cat exposure was not associated with an increased risk of moderate-to-severe asthma (adjusted OR 0.96).
Similarly, asthma exacerbations (i.e., attacks or flare-ups) occurred in 3.3% of cat-exposed children and 3.5% of non-exposed children (adjusted OR 1.12).
The findings were equally reassuring when researchers looked at objective measures of respiratory health.
Among a subset of 1428 children who had available asthma control and spirometry data, there were no significant differences in asthma control test scores, forced expiratory volume in one second (FEV₁), or FEV₁/FVC ratios between those living with cats and those who were not.
Even within cat-owning households, researchers found no evidence that certain types of cats posed a greater risk.
“We also did not see any differences in asthma outcomes related to the number of cats, the cat’s sex, or the cat’s age,” said Dr Resthie Putri, a postdoctoral fellow at Sweden’s Karolinska Institutet and one of the study authors.
One possible explanation, according to the researchers, is that cat allergen exposure is far more widespread than many people realise.
“Children who do not have cats at home may still be exposed in shared environments such as schools or public transportation, which could explain why we didn’t see a difference,” Dr Putri said.
Related
The authors also noted that long-term exposure to cat allergens may influence immune responses in ways that differ from occasional exposure. Some evidence has suggested that sustained exposure can promote the production of antibodies that reduce allergic inflammation, although the exact mechanisms remain uncertain.
However, the researchers cautioned that their findings should not be interpreted as proving that cats can never trigger symptoms in individual children.
“While these large-scale findings provide valuable insight, we lacked data on which allergens the children were sensitized to, and because the National Cat Register is relatively new, some children living with cats may have been misclassified as unexposed,” Dr Putri said.
The study also focused specifically on children with asthma and allergies and therefore may not apply equally to all asthma phenotypes. Nevertheless, it adds to the growing evidence that blanket recommendations to remove cats from households may not be warranted for all children with asthma and allergies.
For parents worried that the family cat may be making their child’s asthma worse, the findings offer some welcome reassurance, although individual circumstances should still guide decisions about pet ownership.
