Children who live with dogs and cats are less likely to develop allergies to those
animals later in life, but only if the pet is under the same roof while the child is still
an infant, a new study suggests. Compared to babies born into cat-free homes, those
who grew up with cats were roughly half as likely to be allergic to them as
teenagers, the study found. Growing up around a dog reduced the risk of dog
allergies by about the same amount for boys, but not for girls — a finding that
mystified researchers. [ i ]
Being exposed to pets anytime after the first year of life appeared to have no
effect on allergy risk, however, which indicates that timing may be everything when
it comes to preventing allergies.
Though they can’t say for sure, the researchers suspect that early exposure to pet
allergens and pet-related bacteria strengthens the immune system, accustoms the
body to allergens, and helps the child build up a natural immunity. “Dirt is good,”
says lead researcher Ganesa Wegienka, Ph.D., summing up the theory. “Your
immune system, if it’s busy with exposures early on, stays away from the allergic
immune profile.” [ ii ]
This isn’t the first study to find that having a household pet may protect kids
from allergies, but it is the first to follow children until they were 18 years old.
Previous studies have had mixed results — some have even linked pet exposure
during infancy to an increased risk of allergy — so it’s too early to recommend
getting a dog or cat just to ward off allergies in your infant, says David Nash, M.D.,
clinical director of allergy and immunology at the Children’s Hospital of Pittsburgh.
“In the end, we’ll probably find out that there are periods of opportunity when
exposure to allergens, for some people, is going to have a protective effect,” says Dr.
Nash, who was not involved with the new study. “But we’re a long way from
figuring out who it’s protective for and when that optimal period is.” [ iii ]
By the same token, don’t give away your beloved family pet because you’re
concerned the critter will provoke allergies. “I would not get rid of my dog if I was
having a child,” says Wegienka, an epidemiologist in the department of public health
sciences at Henry Ford Hospital, in Detroit. “There’s no evidence that you should get
rid of a dog or a cat.” [ iv ]