Pet Allergies Pose Tough Questions

Q:  My daughter has asthma and allergies to dogs. I read that growing up with animals actually protected you from allergies and that it was better to be exposed to some dirt than to live in a spotless house.

So must I really find a new home for our dog? We are quite attached to her.

A:  I forwarded this tough question to Dr. Ria Chiu, Assistant Professor of Medicine/Pediatrics and an allergy specialist at the Medical College of Wisconsin. She reports that a 2001 study did find that growing up with some furry pets reduced the risk of frequent wheezing later in life.

However, there are caveats to this study: cats were not found to be protective, you needed to have more than one dog, you had to be exposed since birth, you couldn't have a family history of asthma, and early exposure to furry pets didn't decrease risk for allergy, only frequent wheezing.

Furthermore, the authors of this study published another study in 2002 that did not find this advantage of furry pets during childhood. Chiu mentions that research based on the cleanliness of a home is even more confusing and controversial.

Since your daughter has already been diagnosed with asthma and dog allergy, it really doesn't matter what her previous exposures have been. In other words, even if the 2000 study is correct, your daughter was one of the unlucky ones who developed asthma despite growing up with a dog. At this point, removal of the allergic trigger (the dog) is the best thing for your daughter in the long run.

If you are unable to do this, Chiu says there may be other things you could do to at least decrease exposure, such as keeping the pet out of the bedroom and using HEPA filters in the bedroom and in the family areas where the pet is. Chiu adds that, in general, if asthma due to pet allergy becomes difficult to control, it may be a sign to start looking for other homes for that pet. (Sorry.)

For more information on this topic, see the HealthLink article Hygiene Hypothesis: Are We Too "Clean" for Our Own Good?

Julie L. Mitchell, MD, MS, is an Assistant Professor of Medicine at the Medical College of Wisconsin. She practices internal medicine at the Froedtert & Medical College General Internal Medicine Clinic - East. Her column appears in the Milwaukee Journal-Sentinel.