We have all heard that dogs are man’s best friends. That may be doubly true for children. But unless you are a pediatrician or a microbiologist who has been following this story for a long time, you might be surprised to learn why.
A new study in JAMA Pediatrics suggests that children who are exposed to dogs or farm animals early in life may be less likely to develop asthma as they age. In this cohort study, investigators tracked all children born in Sweden between January, 2001, and December, 2010. Over one million children were included in the study.
Do Puppies and Ponies Protect Kids from Wheezing?
Babies who had dogs in their homes during their first year of life were about 13 percent less likely to have developed asthma by their sixth birthday.
If they grew up on a farm (with cows, horses, pigs, goats or other animals), their odds were even better. Children exposed to farm animals early in life were only about half as likely to develop asthma as their suburban or urban counterparts.
The authors conclude: “This information might be helpful in decision making for families and physicians on the appropriateness and timing of early animal exposure.”
JAMA Pediatrics, online Nov. 2, 2015
Previous Research Linking Dogs at Home and Less Asthma Later:
This is not the first time that a link has been detected between early exposure to dogs or farm animals and a lower likelihood of asthma, allergies or eczema. A study published in the New England Journal of Medicine (Feb. 24, 2011) demonstrated lower rates of asthma and eczema among kids who grew up on farms in Central Europe. The researchers looked for bacterial DNA in kids’ mattresses or rooms, and found that the farm youngsters were exposed to a wider range of bacteria than urban children.
Why Dogs Make a Difference:
Another study exposed mice (not human children) to dust from homes in which dogs had lived and dust from dog-free homes. Those exposed to doggie dust had changes in their intestinal microbiota, especially a higher prevalence of Lactobacillus johnsonii, that were associated with a reduced risk of asthma-like changes in the lungs (Proceedings of the National Academy of Sciences, Jan. 14, 2014).
There seems to be growing evidence for the hygiene hypothesis, an idea that making babies’ immune systems respond to a range of bacteria and fungi early in life channels them toward recognizing such potential pathogens and helps keep them from turning to auto-immune attacks. A 2012 Finnish study found that infants from households with dogs were 29 percent less likely to need antibiotics during their first year and 44 percent less likely to have inner ear infections (Pediatrics, July, 2012).
A guest blog describes the health benefits of having a pet-dog or cat. We also had a fascinating discussion with Dr. Daphne Miller about her book, Farmacology, in which one chapter is devoted to evidence for the hygiene hypothesis.
