Eczema, Asthma, and the Protective Effect of Dogs

Eczema and asthma affect an estimated 32 million and 18 million Americans, respectively, and both conditions are more common in children than in adults:

• Eczema prevalence: 13% of children and 7.2% of adults
• Asthma prevalence: 7.6% of children and 8.4% of adults

But according to 2 new studies presented at the American College of Allergy, Asthma, and Immunology (ACAAI) Annual Scientific Meeting in late October, exposure to dogs may help prevent both of these conditions in children.

Dogs and Eczema

The first study, led by Detroit allergist Gagandeep Cheema, MD, examined dog exposure among pregnant women to determine the risk of childhood eczema.

“Many people don't know there is a progression from eczema to food allergies to nasal allergies and asthma,” she said. “We wanted to know if there was a protective effect in having a dog that slowed down that progress.”

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The research team found that children born to mothers who were exposed to dogs during pregnancy were less likely to develop eczema by age 2 than children born to mothers who were not exposed to dogs during pregnancy. For the study, “exposure” was defined as keeping 1 or more dogs indoors for at least 1 hour daily.

“We found [that] a mother’s exposure to dogs before the birth of a child is significantly associated with lower risk of eczema by age 2,” said study co-author Edward M. Zoratti, MD. The researchers also noted that this protective effect decreased by the time the children reached age 10.

Dogs and Asthma

The second study examined how exposure to dogs affects asthma severity in urban children. The research team, led by Baltimore allergist Po-Yang Tsou, MD, MPH, examined 2 types of dog exposure on children with asthma:

• Exposure to the protein that affects children who are allergic to dogs
• Exposure to the bacteria or other elements that a dog might carry

The researchers found that exposure to the elements that dogs carry may protect against asthma, but exposure to the allergen itself may exacerbate asthma symptoms.

“Among urban children with asthma who were allergic to dogs, spending time with a dog might be associated with two different effects,” said Dr. Tsou. “There seems to be a protective effect on asthma of non-allergen dog-associated exposures, and a harmful effect of allergen exposure.”

The researchers acknowledge that exposure to dog allergen should still be a major concern for children who are allergic to dogs. Those with dog allergy who still keep a dog in the home should follow these ACAAI guidelines:

• If possible, restrict the dog to only a few rooms, and don’t allow the dog in your bedroom.
• Wash your hands thoroughly after touching your dog.
• Use high-efficiency particulate air cleaners and high-efficiency vacuums to reduce allergen levels.
• Bathe your dog at least once a week.