Aug. 27, 2002 -- Having Fido and Fluffy at home with your new baby may help protect the infant from developing allergies later in life. A new study shows children exposed to two or more cats or dogs in the first year of life are less likely to suffer from allergies than those raised without pets.

"The striking finding here is that high pet exposure early in life appears to protect not only against pet allergy but also other types of common allergies, such as allergy to dust mites, ragweed, and grass," says Marshall Plaut, MD, chief of allergic mechanisms at the National Institute of Allergy and Infectious Diseases (NIAID), which helped sponsor the study, in a news release.

Researchers followed 474 infants for about seven years and found that children exposed to two or more cats or dogs in their first year of life were 75% less likely to be sensitive to these common allergy triggers at age 6 compared with those with no pets.

Compared to children that were not exposed to cats or dogs, those who were raised with two or more indoor pets were half as likely to develop common allergies.

The researchers say their findings signal a drastic change in the way doctors should look at pets and allergies. Their report appears in the Aug. 28 issue of The Journal of the American Medical Association.

"Allergists have been trained for generations that dogs and cats in the house were bad because they increased the risk of you becoming allergic to them; we know that before you become allergic to something, you have to be repeatedly exposed to it," says study author Dennis Ownby, MD, chief of the Medical College of Georgia Section of Allergy and Immunology, in a news release.

Allergies and sensitivity to common allergy triggers have been linked to a higher risk of asthma, and researchers say understanding what causes children to develop allergies may help stem rising rates of childhood asthma.

The researchers suggest that exposure to cats and dogs helps the body develop a better immune response to common allergy triggers because the animals contain substances called endotoxins in their mouths. Endotoxins are thought to activate a portion of the immune system that reduces the risk of becoming allergic.

"What happens when kids play with cats or dogs? The animals lick them," Ownby says. "The lick is transferring a lot of [endotoxins] and that may be changing the way the child's immune system responds in a way that helps protect against allergies."

"The bottom line is that maybe part of the reason we have so many children with allergies and asthma is we live too clean a life," says Ownby.