WEDNESDAY, May 21, 2003 (HealthDayNews) -- Rex may be your best pal, but if you've got asthma he is your lungs' worst enemy.
More people are allergic to cats than dogs. However, a new study shows dog allergens are more ferocious irritants to asthmatics than cat dander, cockroaches, mold and dust mites.
The researchers presented their findings May 20 at a meeting of the American Thoracic Society in Seattle.
The study included 809 men and women with mild to moderate asthma who underwent skin tests for various irritants.
To measure their sensitivity to an allergen, the researchers tested subjects in four areas: their ability to exhale while exposed to an irritant (weaker is worse); the amount of nitric oxide gas in their breath (more signals inflammation); and the nature of the phlegm, if any, they coughed up (cells called eosinophils present in mucus reflect inflammation). They also provoked their lungs with a drug that simulates constricted airways.
Cat allergens were most likely to trigger at least one of these reactions, doing so in nearly three-quarters of the volunteers, the most of any irritant. Dog dander, by comparison, did so only about half as frequently.
However, dog dander was the irritant most likely to decrease lung function, constrict the airways and provoke inflammation.
Recent research has suggested cats in the home can protect infants from early-childhood asthma. However, the new study shows that both dogs and cats are a problem for adults with the breathing problem.
"Once you have asthma, both of the critters can increase inflammation and decrease the stability of asthma," says Dr. Tim Craig, a pediatrician at Pennsylvania State University College of Medicine and a collaborator on the work.
Interestingly, the researchers say, pollens didn't seem to exacerbate the lungs as much as dog and cat dander and other indoor irritants. "Though they cause significant symptoms, like runny noses and itchy eyes, they may not be as important triggers of asthma as indoor allergens are," Craig says.
Dr. Clifford Bassett, a New York City allergy specialist, says the new findings run counter to what most asthma experts have believed. "Normally we think cat dander is most provocative," says Bassett, who sits on the public education committee of the American Academy of Allergy, Asthma and Immunology.
Some doctors say pets are a no-go for asthma patients. Bassett says it's possible to keep animals around, as long as you take steps to reduce your exposure to their allergens. Using special air filters to intercept the particles is one way, while lower-tech measures such as wearing cotton (wool's a magnet for pet dander) and keeping your animal out of the bedroom help, too. "Keeping your pet out of the bedroom can reduce your allergy symptoms by 30 percent," Bassett says.
Also important, Bassett adds, is that everyone with asthma should be tested for allergies. "Certain allergies can be modified" with lifestyle changes, prevention or medication, he says.
An estimated 4 million to 5 million children in this country have asthma. For more on the breathing disorder, try the American Academy of Allergy, Asthma and Immunology or the U.S. Environmental Protection Agency.