Pet exposure may reduce allergies. (Biomedicine).

Parents concerned about allergies may balk at the idea of keeping pets around children. However, new research suggests that babies exposed to cats and dogs are less likely than others to develop the symptoms--itching, sneezing, and wheezing--that make up an allergic reaction in later life.

"Traditionally, allergists recommend that expectant parents who ... want to reduce the risk for their children not have a pet," says epidemiologist Christine Cole Johnson of Henry Ford Hospital in Detroit.

Johnson and her colleagues set out to test the advice. Starting in 1987, the scientists monitored 474 Detroit children from the womb to around 7 years of age. During this time, they collected data on the parents' history of allergies, the children's health, and conditions in the homes.

Johnson's group tested the children when they were 6 years old for common allergies to dogs, cats, dust mites, grass, and mold. The scientists found that the children who never had pets were around four times as likely to have an allergic response as were children exposed to two or more cats or dogs in the first year of life.

"This is exactly the opposite of what we would have predicted," says coauthor Dennis R. Ownby at the Medical College of Georgia in Augusta. The findings are detailed in the Aug. 28 Journal of the American Medical Association. Ownby suggests that homes with pets have higher amounts of bacterial-breakdown products than pet-free homes do. These products may force the immune system to develop response patterns that make it less sensitive to allergens in later life, he says.--J.P.