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CHICAGO -- Racial and ethnic differences in childhood asthma rates might be associated with exposure to pets -- or lack thereof -- at an early age, a cross-sectional study suggested.
Among children with asthma, Caucasians were more likely to have cats, dogs, or both in the home than were African American or Hispanic children (all P<0.001 to P=0.003), Shahid Sheikh, MD, of Nationwide Children's Hospital in Columbus, Ohio, and colleagues found.
The findings add some support to the literature favoring a protective effect of early exposure to dogs and cats, he told MedPage Today.
"Many people say if you have a pet early in life you may get sensitized, you may have increased symptoms, for a little while but then your body reacts to that and a lot of children who are exposed early in life to pets do develop some protection against [later] allergy and asthma from pet exposure," he explained.
Other studies haven't supported such a pattern, though, and there may be complex interactions with timing of exposure and level of antigen, he noted.
"We know that [pet exposure is] one of the triggers that leads to worsening asthma or asthma development," session co-chair Jonathan Popler, MD, of Georgia Pediatric Pulmonology Associates in Atlanta, told MedPage Today.
He called the lack of data on whether animals in the home predated the child's asthma a problem in Sheikh's study.
"There is still more we don't know than we do know," Sheikh acknowledged. "We are not saying everyone should go and buy a pet."
It would be premature for families to act based on any single study, he said.
His group's study included 500 children with asthma at the Nationwide Children's Pediatric Asthma Center, whose families completed a questionnaire on their initial visit detailing race, ethnicity, and pets in the home.
The kids were a mean 7-years-old and had had asthma for an average of 4.5 years. Caucasians accounted for 70% of the cohort, followed by African Americans at 23%, and Hispanics rounding out the remaining 7%.
Overall, 62% of the families reported having a pet in the home. The national average, based on a survey by the American Veterinary Medical Association, is 37% of households with dogs and 30% with cats.
But the rate varied substantially along racial and ethnic lines in the asthma cohort, as expected from the national data. The survey showed the most dogs in Caucasian households, the fewest in African American homes, with Hispanics falling in between.
In Caucasian families of children with asthma in Sheikh's study, 55% had only dogs, 27% had only cats, and 19% had both.
In the Hispanic families, 38% kept dogs in the home, 9% had cats, and 9% both types of pets.
In African American homes with asthmatic children, 30% had dogs, 8% cats, and 6% both cats and dogs.
Each comparison turned up significantly more of each type of pet in the Caucasian families, whereas the African American and Hispanic families' rates came out similar to each other.
Lack of multivariate analysis accounting for differences, such as socioeconomics, tobacco smoke exposure, type of housing, age at exposure to an animal in the home, and other key factors, was a limitation, Sheikh noted.
Prior studies have suggested poverty and education are simply markers for asthma risk that differ among ethnic and racial groups rather than causal factors, he pointed out in an interview.
"Further studies on the contributing and protective effects of pets on children's respiratory symptoms and development of asthma are needed," he acknowledged.
The researchers reported having no conflicts of interest to disclose.