Cats may be trouble for any allergy sufferer

By Amy Norton

NEW YORK (Reuters Health) - People with allergies may have some constriction in their airways when they're around a cat, even if they're not specifically allergic to cats, a study published Monday suggests.

Researchers found that people with a range of allergies -- to grass, mold or dust -- were more prone to airway constriction if their homes were heavy with cat dander. This was true even when blood tests showed the allergy sufferers were not specifically sensitized to cats.

While the airways of the lungs naturally constrict to some degree in response to an irritant, exaggerated responses are seen in lung conditions like asthma.

If the new findings are correct, people with any type of allergy would do best to avoid cats, according to the study authors.

However, it's too soon to put Fluffy in a new home just yet. The findings were unexpected, lead researcher Dr. Susan Chinn told Reuters Health, so they need to be confirmed in additional studies.

Chinn, a research fellow at Imperial College London, and her colleagues report the findings in the American Journal of Respiratory and Critical Care Medicine.

The study included 1,884 adults from 20 areas across Europe. Researchers went to participants' homes to take measurements of dust mite and cat allergens, and all underwent blood tests to detect allergies to any of four substances: cat dander, dust mites, grass or mold.

Study participants were also given tests of bronchial responsiveness, which refers to the degree of airway constriction in response to an irritant -- in this case, a chemical called methacholine.

Chinn's team found that allergy sufferers, regardless of type, showed greater airway constriction on these tests when their homes contained a relatively higher amount of cat dander. There was no similar pattern when it came to dust mite exposure, however.

If these findings are confirmed in future studies, people with any type of allergy may need to limit their contact with cats, according to Chinn.

That might even mean avoiding cat-friendly neighborhoods, she noted. In an earlier study, Chinn and her colleagues found that the level of cat allergen in non-cat-owners' homes depended on the number of cats in the neighborhood.

SOURCE: American Journal of Respiratory and Critical Care Medicine, July 1, 2007.