Both positive and negative associations between cat ownership and both clinical allergic sensitization and asthma have been identified. In addition, asthma prevalence is very high in inner-city settings and requires ongoing research. This prospective cohort study sought to establish the direction of the association among children in an urban setting. Children were evaluated from birth to 5 years, and mothers completed sequential questionnaires about demographic and environmental information. Serum samples were drawn from children at age 2 (n = 323), age 3 (n = 336), and age 5 (n = 242) and were assayed for anticat IgE and anti-Fel d1 IgG antibodies. In addition, dust samples from homes were collected prenatally and at 3-year-old visits and evaluated for cat allergen Fel d1. Univariate and logistic regression models were used to analyze the data. Mean cat allergen values in cat homes were significantly higher than in nonpet homes; Fel d1 was measurable in 46% of homes without a cat. Development of anticat IgE by age 2 years was significantly more frequent in homes with cats, although this association disappeared between 2 and 5 years of age. Children with anticat IgE at ages 3 and 5 exhibited significantly more wheezing, but owning a cat was inversely associated with wheezing at age 5 in children without anticat IgE.

COMMENTARY: This interesting study evaluated the association between cat ownership and allergic potential. The authors suggested that cat ownership may protect against wheezing, although cat ownership was also associated with allergic sensitization. The sample size was small, and further research with increased sample sizes and power calculations might help further solidify the hypothesis and associations. Such studies are important contributors to the understanding of allergic pet-associated disease in children.

Cat ownership is a risk factor for the development of anti-cat IgE but not current wheeze at age 5 years in an inner-city cohort. Perzanowski MS, Chew GL, Divjan A, et al. J ALLERGY CLIN IMMUNOL 121:1047-1052, 2008.