Dogs in the House
May Cut Kids' Allergy Risk
NEW YORK (Reuters Health) - Young children who share their home
with two dogs or cats in the first year of life are half as likely
to become allergic to those animals than kids who grew up with
only one dog or cat, or no pets, according to new study findings.
The finding flies in the face of advice given out by pediatricians
and allergists for the last three decades, lead researcher Dr.
Dennis R. Ownby of the Medical College of Georgia in Augusta noted
in an interview with Reuters Health. Conventional wisdom has held
that having a pet increases a child's risk of developing an allergy
to that animal.
"Evidence is mounting that the opposite is true," Ownby said.
He added that, "surprisingly," exposure to two dogs or cats also
seems to cut the risk of developing other common allergies, such
as sensitivity to dust mites and pollen.
While Ownby isn't calling for everyone with newborns to rush
out and get two pets, he says the new findings should allow parents
who already have pets to breathe a sigh of relief.
"These parents don't have to feel guilty that they are increasing
their child's risk for allergies or asthma," he told Reuters Health.
In the current investigation, published in the August 28th issue
of The Journal of the American Medical Association, Ownby and
his team assessed the home environments of a group of 474 healthy
children, starting at 1 year of age and continuing until they
were 6 or 7 years old.
At the end of the study period, all of the children were tested
for six common allergies: two type of house dust mites, dog, cat,
ragweed and blue grass. Sensitivity was gauged by evaluating a
child's skin reaction after he or she was given a skin prick test
with the allergen.
Only 15.4% of the children with two cats or dogs in the house
during the first year of life showed sensitivity to dogs or cats.
The percentage of children with one dog or cat, or no pets, who
had a positive skin test for dog or cat allergy was about 34%,
the report indicates.
Kids who lived with two cats or dogs as infants were also half
as likely to test positive for any one of the six common allergens
compared with children with fewer or no pets, according to the
While allergies can be inherited, whether or not a child's parents
had allergies did not influence the likelihood that the family
would have pets, so this did not appear to be a factor in the
The results support previous research that has found children
growing up on farms, especially with farm animals, have fewer
allergies, the authors note.
It is possible, Ownby explained, that increased exposure to
common bacteria and their byproducts--called endotoxins--somehow
causes the developing immune system to become less allergy-prone.
Most importantly, the researcher noted that the results suggest
something in the environment can reduce the risk that allergies
will develop. Further studies on the issue may help pinpoint what
exactly that environmental element is, and help doctors to find
a way to prevent children from developing allergies, he added.
Regardless of the current study findings, Ownby advises parents
with known dog or cat allergies to steer clear of these pets.
Allergies tend to run in families, he pointed out, and their children
may already be allergic.
Commenting on the study, Dr. Thomas A. E. Platts-Mills of the
University of Virginia Health Sciences Center in Charlottesville
writes: "The new findings in relation to domestic animals provide
an opportunity to understand the aspects of the allergic response
that create risk for asthma; the mechanisms by which high exposure
to foreign protein (i.e., the allergens in animal dander) can
give rise to tolerance; and also, the factors that control the
prevalence of allergic disease."
SOURCE: The Journal of the American Medical Association 2002;288:963-972.
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