A newborn’s immune system needs time to figure out what should be fought and what should be ___1___. Conventional wisdom had it that early exposure to potential troublemakers, from peanuts to pets, could lead to allergy issues later.

But recent research shows that having a dog or cat at home isn't likely to make children ___2___ to animals. And a new study finds that kids who grow up with pets are less likely to have an animal allergy all the way through age 18. The works is in the journal Clinical & Experimental Allergy. [Bill Hesselmar et al., "Does early exposure to cat or dog protect against later allergy development?"]

The key to this ___3___ was having a mostly indoor dog or cat before a baby's first birthday. Infants with cats at home had half the normal risk of a cat allergy when teenagers. And boys with a dog during their first year had half the risk of later allergies to dogs.

Researchers are still debating why early pet exposure helps keep allergies ___4___. Some think that all the extra dust, dander and bacteria train a baby’s immune system, stopping it from reacting unnecessarily.

Now, getting your ___5___ to stop pulling the cat's tail, that's another question.
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