Patient Education - Should Allergic Families Have Pets?
By Neil Gershman, M.D.
It is well accepted that furred pets contribute to allergic diseases such as allergic rhintis (hay fever), asthma, and atopic dermatitis (allergic eczema). We allergists often see patients who are experiencing sneezing and wheezing that is due directly to breathing in cat and dog dander particles. Symptoms can improve greatly with total avoidance of the pets, but patients are usually unwilling to part with their beloved animals.
So, we often suggest rinsing the pets with water twice a week, having the bedroom off-limits to the pets, removing reservoirs of the dander (e.g. replacing carpet with tile, putting allergy-proof encasements on mattresses), and using HEPA filters for the bedroom. If this doesn't alleviate the symptoms, medications and/or allergy shots can be helpful.
Also, it should be noted that many patients have other allergens, such as molds and dust mite. If patients are allergic to these substances, then other measures can be taken. If allergies are a problem for any individual, allergy testing by skin test can be helpful in their management.
But a very hot topic in allergy now is whether allergic families should have pets in their homes. To begin with allergies are genetically linked, that is, they run in families. Let's use an example. If a parent has mild allergies to dust mite but not allergic to cats, is it o.k. for the parents to have a pet in the home as they bring up their children. Obviously, if the child develops allergies to an animal, then the avoidance measures should be done.
However, several recent studies looking at large groups of people have found an interesting trend - that children born into a house with a pet were somewhat LESS likely to become allergic than those children born into a house without pets. No one knows why this may occur, but the two main theories are:
1. High exposure to an immature immune system of an infant to animal allergens tends to tune down the allergic process.
2. Exposure to tiny amounts of animal waste products distract the infants immune system, and direct it toward non-allergic activities.
There have been several studies in the past that showed that high exposure of infants to dust mite lead to more allergies, suggesting that there is something different about animal allergens and dust mite.
Also very interesting is a recent study in the May 2002 issue of "Epidemiology" showing that older children were MORE likely to develop asthma if they had pets, especially dogs, in their homes. The study also showed that there was in increase in asthma with the use of humidifiers and having over four house plants in the house (suggesting that dust mite and mold avoidance may be important in prevention).
So, we are left with some controversy. It seems like infants may be protected from developing allergy if they are brought up in a home with pets. Older children who don't have allergies yet, may be more likely to develop them if animals are in the house. Consequently, we don't know what to tell future allergic parents. Until more information comes out, most allergist are still recommending avoidance of furred pets (fish, birds, reptiles aren't much of a problem). However, we all strongly recommend dust mite and mold avoidance measures in homes of potentially allergic children - that is, no carpeting, limiting the amount of house plants, and keeping the home cool and dry.