Early-life cat, dog ownership not linked to school-age asthma

Owning a dog or cat early in life did not increase the risk for school-age asthma or contribute to cat- and dog-related allergic sensitization, according to a study published in The Journal of Allergy and Clinical Immunology.

However, those with cat- or dog-specific allergic sensitization did appear more at risk for school-age asthma, results also showed.

Angela Pinot de Moira, PhD, an epidemiologist and postdoctoral researcher in public health at University of Copenhagen, and colleagues wrote that the exact relationship between allergen exposure and development of allergic sensitization and symptoms such as asthma are not fully understood.

To examine the association of early-life cat and dog ownership with the development of asthma in childhood, the researchers analyzed data from 77,434 mother and child pairs from a range of cohorts. The children were aged 5 to 11 years.

Pet ownership ranged from 12.2% to 45.1% for cats and 7.4% to 47.4% for dogs among study cohorts. A mix of prenatal and early childhood (from conception to age 2 years) appeared to be the most common time for pet ownership, whereas prenatal only was the least common timing.

Overall, data did not correlate early-life cat (OR = 0.97; 95% CI, 0.87-1.09) or dog ownership (OR = 0.92; 95% CI, 0.85-1.01) with asthma at school age, nor with wheezing in infancy or any connection with parental asthma rates.

Additional analysis showed no evidence to connect cat and dog ownership with overall lung function.

Odds for school-age asthma were also similar regardless of the number of cats or dogs owned, but ownership prenatally only did appear associated with a trend toward greater odds of school-age asthma for cats (adjusted OR [aOR] = 1.17; 95% CI, 0.96-1.42) and dogs (aOR = 1.08; 95% CI, 0.88-1.33).

Researchers also found cat and dog ownership was not linked to cat- and dog-specific allergic sensitization.

Although both cat- and dog-specific allergic sensitization were associated with school-age asthma, which the researchers said was “possibly” greater among cat and dog owners (cats: aOR = 6.55; 95% CI, 3.66-11.71; dogs: aOR = 23.36; 95% CI, 6.01-90.79), they also found ownership may offer “some protection against asthma among children who do not develop allergic sensitization.”

Noted limitations from the study include the potential for selective avoidance of pets, especially cats, among families with established asthma and allergies.

“Similarly, it is also possible that the development of early respiratory symptoms in the child, for example infant wheeze, may result in the removal of pets from the home; this may be less common than avoidance, however,” Pinot de Moira and colleagues wrote. “Although we have tried to assess these possibilities by investigating whether parental asthma and infant wheeze modified results, a preferred approach would be to exclude children whose parents reported avoidance of pets due to allergies or asthma in the family. Unfortunately, these data were not available in the majority of cohorts.”