Infants exposed to two or more cats or dogs during the first year of life appear to be protected against several common allergies later in childhood.
Children exposed to pets, viruses and dust (Clin Exp Allergy, 1999; 29: 611-7; BMJ, 2001; 322: 390-5; Lancet, 2000; 35: 1680-3) at an early age have less asthma as they get older.