Effect of household pet ownership on infant immune response and subsequent sensitization

Sensitization to pets is a major risk factor for asthma. There are many reports on the relationship between household pets, sensitization to the pet, and sensitization to other allergens, often with conflicting results. Pet ownership is not random, and household pets are associated with exposures other than pet allergens. We will review some of the evidence regarding the effects of household pets on infant immune responses, focusing on data from birth cohort studies. It remains unclear precisely why some children develop specific sensitizations to pets whilst others do not in the face of equivalent exposures, but it is likely to be due to gene-environment interactions. Further long-term follow-up of children in whom neonatal and infant immune responses have been measured is necessary to understand how these events occur and how they relate to subsequent disease.