Will getting a pet prevent allergies for my kids? That is a tough question. Recent studies show a significant reduction in risk of sensitization against dog and cat only if exposed to the animals in the first year of life. Cumulative exposure had no effect on later sensitization. Of the 566 participants followed in the study, at age 18, 18% were allergic to dogs and 20.5% allergic to cats. In males, exposure to a dog in the first year of life reduced the risk of dog allergy by half. For both genders, exposure to an indoor cat in the first year of life was associated with a decreased risk of cat allergy almost by half. Exposure to the animals after the age of 1 including cumulative exposure throughout childhood and adolescence, has no effect on sensitization risk.
Source:Wegienka G, Johnson CC, Havastad S, et al: Lifetime dog and cat exposure and dog- and cat- specific sensitization at age 18 years. Clin Exp Allergy. 2011;41:979-986.