Doctors have long believed that the best way to prevent babies from developing allergies is to keep them away from cats and dogs. But a new study adds to the mounting evidence against that conventional wisdom. Having more pets around a baby may reduce its risk of allergic sensitivity later on.
Six-year-old Julianna Turner loves playing with her dog Katie. "I like to kiss her and she kisses me back," she says.
But Julianna's allergies forced her mother to move the dog outside years ago. Now a new study the Journal of the American Medical Association says it may have been better to get more pets instead.
"This is exactly opposite of what we would have expected, that dogs and cats appear to be good and not a risk for children," he said.
Pediatrician Dennis Ownby of the Medical College of Georgia and colleagues tracked a group of nearly 500 healthy babies in suburban Detroit from birth to about age seven. Their findings show that children who had lived with two or more dogs or cats during their first year of life were only about half as likely to develop allergies as were children with one pet or no pets.
Dr. Ownby says the protection went beyond preventing reactions to just animals. It includes dust, grass, and ragweed, too. "Having dogs and cats in the household actually reduces the risk not only that a child will be allergic to cats and dogs, but that they'll be allergic to any common allergen," he said. "In fact, it seems that the more cats and dogs, the better."
The findings support several similar European studies of the past few years, including some in agricultural communities showing that early exposure to farm animals protects against asthma.
Scientists are not sure why the immune system reacts this way.
According to one hypothesis, early exposure primes it in such a way to favor cells associated with conferring immunity to disease over that cause allergic inflammation.
A Journal of the American Medical Association editorial accompanying the study says that it provides an opportunity to understand allergic responses and factors that control allergies.
Julianna's mother, Lisa Turner, says she wishes this study came out years ago. "My first reaction was, 'Wow, why didn't we have several pets with Julianna?' because she loved having pets around so much," she said.
But the study findings pertain only to children who had multiple cats and dogs as babies. Juliana has had only one, so her pet will have to stay outside.