The incidence of allergy and asthma is rising in recent years. Although this is true for all age groups, it is most particularly evident among adolescents. The increased susceptibility to hay fever, wheezing and asthma has been that our modern way of living does not provide the optimum exposure to a wide enough range of allergens at an early enough age. To further investigate this, a recent study investigated the relationship of pet exposure during pregnancy and infancy with the subsequent development of childhood allergies and asthma. The result is good news for pet lovers, especially of the furry variety!

Exposure to furry pets such as dogs and cats during a critical immunological window early in life is associated with lower risks of allergy, atopic dermatitis, asthma, and even obesity. The difference seems to be an increasing abundance of particular microbes that children acquire when they are around pets. The mechanism for that difference relates to specific alterations of the infant gut microbiome during a crucial developmental period that extends from before birth in the womb across the first few months of life.

The microbiome is a term that is used to encompass the enormous variety of microbes that inhabit various parts of out body, such as our gut, skin, or respiratory systems. The colonization of our gut by microbes is an essential aspect of our life cycle and influences every developmental stage. The neonatal period and infancy are now understood to be a critical crossroad for the accumulation of microbes that will affect the remainder of our lives. Pet ownership is among several environmental factors that are known to contribute to this crucial process.

The study concentrated on the influence of furry pets on the infant gut microbiome when pets were in the house beginning with the second and third trimesters of pregnancy extending into the first 3 months of life. When the gut microbiome of the children that were exposed to pets was sampled at a few months of age, there was a significant increase in the bacterial strains known to be associated with lower incidences of childhood allergy, asthma and childhood obesity compared to those that were not. A surprising finding was that even if the pet was given up for adoption just before birth, the infant gut microbiome was still positively affected. That influence was even sustained under some of the circumstances that are clinically associated with lowered neonatal immunity, such as birth by cesarean section, antenatal maternal antibiotic usage, or the absence of breast-feeding. An additional positive effect that was also documented was a decreased rate of transmission of group B Streptococcus to infants, a bacterial strain as that has been associated with neonatal pneumonia.

This is known as the 'microbiota hypothesis.' The idea is that as we urbanize and sanitize, we are no longer associating with important microbes in the same way that we had in the past. For example, numerous epidemiological studies have confirmed that children that grow up on farms are largely protected from asthma, hay fever, and a wide variety of allergic sensitizations. Contact with livestock and their feed from birth onward into adulthood seems to prevent the allergies and asthmatic reactions that afflict modern societies. A further study that concentrated on inner-city urban environments found that the greater the amount of exposure in the first year of life to cockroaches, mouse droppings, cats, and the microbes associated with them, the lower the incidence of recurrent asthmatic wheezing and allergy symptoms.

These new findings about our microbiomes are even changing our understanding of ourselves. They are crucial participants in our health, development and wellbeing. They contribute critical aspects of our metabolism, immune systems, digestive health, and nervous system function. They even influence our behaviors and moods, participate in controlling our weight and help govern our feelings of hunger or satiety.

Pet owners have long understood that the animals they love are affectionate companions and stress relievers that are crucial participants in their healthy lifestyle. Now they can take satisfaction in knowing that they are also a boon for children's microbiomes during that critical immunological period that extends from pregnancy through the first years of life.

Dr. Bill Miller has been a physician in academic and private practice for over 30 years. He is the author of The Microcosm Within: Evolution and Extinction in the Hologenome. He currently serves as a scientific advisor to Prebiotin and OmniBiome Therapeutics, a pioneering company in discovering and developing solutions to problems in human fertility and health through management of the human microbiome. For more information, www.themicrocosmwithin.com.