Study Finds Cats Make Allergies Worse, Even For People Without Cat Allergies

People love their cats. Felines can offer an aloof but unconditional love. But for people who have certain common allergies, a new study suggests cats may increase their suffering, even if they are not allergic to cats.

The study, published in the first July issue of the American Journal of Respiratory and Critical Care Medicine, found even moderate exposure to cat allergen is associated with greater bronchial responsiveness.

Dr. Susan Chinn and 12 other researchers at the Imperial College of London examined data from 1,884 participants in 20 different centers across Europe. The data measured levels of dust mites and cat allergen in mattress dust samples, and people's sensitivities to four major allergens: cat, house dust mite, Cladosporidium (a common mold), and timothy grass.

No correlation was found between the levels of house mite dust and bronchial responsiveness, which includes breathlessness similar to the early stages of asthma, for patients with sensitivity to any of the four tested allergens. But even moderate exposure to cat allergen resulted in a significantly greater responsiveness, Chinn said.

"This was an unexpected finding," Chinn said in a news release. "We presupposed that we would find increased responsiveness only in those individuals who were exposed to cat allergen and whose blood tests showed that they were allergic to cats. But our study suggests that all allergic individuals have signs of asthmatic responses if exposed to cat allergen, even if blood tests show that they are not allergic to cats."

This study supports earlier research that has found asthma is strongly related to indoor allergens. More than 25 percent of the individuals examined were sensitized to at least one of the allergens tested.

Researchers said this shows that avoidance of cat exposure would be beneficial to many more people than previously thought. The authors did not go so far, however, as suggesting cat-owning allergy sufferers need to toss the cat out of the house for good.

"Based on the current research, it appears that many individuals could benefit from reduced cat ownership and exposure," Chinn said. "However, because the findings were unexpected, it is important that results are replicated in other studies before firm recommendations are made."

This article was reviewed by Dr. Manny Alvarez.