And living with a cat or dog in infancy may even be protective, researchers find.
Teens who were exposed to cats before age 1 were almost 48% less likely to develop allergic reactions to the pet, according to a study in the journal Clinical & Experimental Allergy. Researchers also found a 67% lower risk of dog allergy in both male and female teens born via cesarean section who were exposed to dogs before age 1.
To see what effect, if any, childhood exposure to cats and dogs has on the development of pet allergies in children, the researchers tested blood samples gathered as part of the Detroit Childhood Allergy Study for the presence of a substance known as animal-specific IgE. The presence of this antibody would indicate that an individual was "sensitized" to that animal, which indicates an allergy. The study began in 1987.
Results of the study from Henry Ford Hospital in Detroit are published online June 13 in the journal Clinical & Experimental Allergy.
At age 18, about 560 of the study's participants agreed to participate in this follow-up study. They provided additional blood samples and pet histories.
During their first year of life, 184 teens had an indoor dog and 110 had an indoor cat.
In males, the risk of having a dog allergy was decreased by 50 percent in those who had a dog during their first year. This association wasn't found in females, however. But when the researchers looked at teens born via cesarean-section delivery, they found that both males and females had a 67 percent decreased risk of dog allergy when they lived with a dog during their first year of life.
Wegienka noted that babies born via C-section aren't exposed to the diverse microflora that babies born vaginally are, which might make their immune systems more susceptible to allergies.
The researchers said that exposure to animals at other times in childhood didn't appear to be as significant as the first year. But, Wegienka cautioned that this study doesn't prove a cause-and-effect relationship between having a pet and avoiding allergies, just an association between those two factors.
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