Body & Mind: Protective Pets

In recent years, doctors have begun to give parents some surprising advice about preventing allergies and asthma in children: let them cuddle up to family pets during the first year of life. The idea, supported by several studies, is to expose the infants to the microbes that make their home in animal fur. That would prime the baby's immune system, still under construction, to recognize common allergens as harmless and not to mount the sneezing, wheezing and red-eyed response.

Researchers from the Medical College of Georgia recently offered more evidence of that effect but added a caveat. Their research, presented at an American Academy of Allergy, Asthma and Immunology meeting, showed that whatever protection pets provide babies is erased if their parents smoke. Children who had two or more dogs or cats before they were 1 year old were 70% less likely to be allergic to ragweed, dust mites and cat and dog allergens by age 7, but that benefit disappeared if they were exposed as infants to cigarette smoke. "What I find most striking is that it appears that this exposure to cigarette smoke is altering the development of the immune system," says lead researcher Dr. Dennis Ownby. "That is pretty shocking." --By Alice Park