Source:Lowe LA, Woodcock A, Murray CS, et al. Lung function at age 3 years: effect of pet ownership and exposure to indoor allergens.
Arch Pediatr Adolesc Med.
2004
;
158
:
996
–1001.

The association between allergen exposure, sensitization, and the development of asthma is complex. Some data suggest that pet ownership protects against sensitization, while other data suggest either no effect or an increased risk of sensitization and asthma development.1,2 While a dose response relationship has been demonstrated between mite allergen exposure and sensitization in children, this exposure does not appear to be directly related to the development of asthma.3,4 The objective of these authors, from Wythenshawe Hospital, Manchester, United Kingdom, was to determine the effect of pet ownership and exposure to indoor allergens on lung function in 3-year-old children.

Subjects were recruited prenatally and followed to age 3 years. Prospectively collected data included airway resistance measured with a body plethysmography at age 3 years, skin prick tests, data on cat and dog ownership, and allergen level in dust collected from living room floors (for dog and cat). Exposure was categorized as “high” when mite allergen levels were ≥2 μg/gram, dog allergens were ≥10 μg/gram, and cat allergens were ≥8 μg/gram.

The authors found that cat or dog ownership at birth or at age 3 years had no effect on pulmonary function, and that mite, dog, and cat allergen exposure were not associated with pulmonary function. Sensitized children exposed to high levels of sensitizing allergen had significantly poorer pulmonary function than children who were not sensitized and not exposed, children who were not sensitized but exposed, and children who were sensitized but not exposed (P=.005). P In other words, pet ownership without exposure or exposure in nonsensitized individuals had no effect on lung function, while the combination of sensitization and exposure to the sensitizing allergen in early life adversely affected lung function. In a multivariate analysis, maternal and paternal asthma and the combination of sensitization and exposure to the sensitizing allergen (with significant interplay between them) were determined to have independent significant associations with lung function. Pulmonary function was significantly worse in sensitized and highly exposed children with both asthmatic parents compared with those with neither or just 1 of those features. The authors conclude that pet ownership and sensitization without exposure or exposure in non-sensitized subjects have no effect on lung function. However, the combination of a specific allergen sensitivity and exposure to that allergen is related to a statistically significant decline in pulmonary function in early life.

Dr. Randolph has not disclosed any financial relationships relevant to this commentary.

This important study demonstrates that pulmonary function in children at 3 years of age declines in the presence of a sensitizing allergen when the host is sensitized. Cat and dog ownership in a non-sensitized host has no impact on lung function. Australian data indicate a significant worsening of peak expiratory flow as mite allergen concentration increases among sensitized children, but no...

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