A dog (but not a cat) at home affords protection against atopic dermatitis

Published Online May 28, 2103

The “hygiene hypothesis” assumes that a reduced exposure to infectious agents in early life can affect the development of the immune system, and has been proposed to explain the increasing prevalence of allergic diseases, including atopic dermatitis (AD). Along these lines, regular contact with animals, and thus increased exposure to microbial agents, during pregnancy or in the first years of life has been examined in several studies in relation to AD.

An investigation from Pelucchi et al, published in The Journal of Allergy and Clinical Immunology (JACI), reviewed all the available information on the relation between exposure to pets and occurrence of AD in infants and children. They analyzed data from 21 birth cohort studies conducted worldwide and, using adequate statistical methods, they calculated summary estimates of the association between pet keeping and AD. They further examined separately the effect of contact with dogs or cats.

The authors found that children who experienced regular contact with pets overall had about a 25% reduced risk of AD. They reported a similar favorable effect for contact with dogs, whereas the analysis showed no meaningful role of cat exposure. The investigators explained the favorable effect of dog keeping through a role of contact with microbial agents during early life, in support of the “hygiene hypothesis.” They suggested that the lack of association with cat keeping might be explained, at least in part, by the different fecal and mucosal microbial communities of these animal species.

The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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