Dogs and smog don’t mix for kids with asthma

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Sawfnews.com

Washington, Aug 29: A dog may be a man’s best friend, but a new research has found that having a pooch in the house may worsen the response to air pollution of a child with asthma.

The study was conducted by a team of researchers led by Rob McConnell, M.D., professor of preventive medicine, at the Keck School of Medicine of the University of Southern California (USC).

The scientists examined the relationship between chronic cough, phlegm production or bronchitis and dog and cat ownership among 475 southern California children with asthma who participated in the Children's Health Study, a longitudinal study of air pollution and respiratory health.

They found that kids with pet dogs had significantly increased cough, phlegm production and bronchitis responses to the measured pollutants, including nitrogen dioxide, ozone, particulate matter and acid vapor.

There were no increases of these symptoms in children who lived in homes without pets or who lived with only cats.

"Cats are highly allergenic, and children with asthma are often allergic to cats. Therefore if an allergen were enhancing the lung's response to air pollution, we'd be more likely to see an association with cats. But in this study we see an effect of air pollution in homes with dogs, so we think endotoxin exposure is a more likely explanation for our results than allergen exposure," said Dr McConnell.

Endotoxin is a part of the cell wall of common bacteria in the environment. Inhaled endotoxin produces a marked inflammatory response in the lungs, and it may cause the airways of people with asthma to constrict.

“There's experimental literature that shows both allergens and endotoxin interact with air pollution and increase the effect of each other. But there's been very little study to see if these experiments have relevance for the general population of children with asthma," he said.

McConnell cautioned that much more study is needed to specify why, exactly, children with asthma living in homes with dogs had an enhanced response to air pollution.

"Further work is needed to determine what it is about dogs that may increase an asthmatic child's response to air pollution," he concluded.

The study appears in the online edition of Environmental Health Perspectives, the journal of the National Institute of Environmental Health Sciences. (ANI)