Can Living With a Dog Prevent Asthma in Kids?

Kids who live with a dog may actually be less likely to suffer from asthma.

Posted Nov 03, 2015

Penn State photo - Creative Commons license
Source: Penn State photo - Creative Commons license

Childhood asthma is a major health concern which seems to have been on the increase during the last decades of the 20th century. Some estimates are that 4% to 9% of children in the 6 to 12-year-old age range have been diagnosed with this problem. Researchers suggest that a number of factors seem to predict asthma, including some that are genetic. However, scientists often point to things in the child's environment, such as tobacco smoke, or more frequently exposure to a cat or a dog in the household as contributing to the onset of the condition. The actual evidence has been mixed on the issue of the the effects of living with a pet, with some reports claiming that pet ownership increases the rate of asthma in children, while the greater number of reports suggest that exposure to pets may actually decrease the likelihood of asthma.

In my experience, I have encountered several people who decided not to get a new puppy when the woman in the household became pregnant. In one case a woman gave away the family dog when she learned that she was about to have a child. In all of these cases the argument was that the presence of the dog might lead to the child developing some form of allergic or asthmatic condition. Thus it was with some interest that I encountered a recent article in the journal JAMA Pediatrics*reported an investigation of the relationship between dog ownership and asthma in children. The research team was headed by Tove Fall, who is an associate professor and a Doctor of Veterinary Medicine at the University of Uppsala in Sweden.

This study took advantage of the fact that Sweden has socialized medicine and there are registries which report all medically diagnosed cases of health problems and prescription drug use. In addition, dog registration is required by law in Sweden. The combination of such registries provides a massive potential for assessing the impact of dog ownership on various health matters. The research team gathered data from every child born in Sweden for the 10 years between 2001 and 2010, which gave them a total of 1,011,051 kids in their data set. The researchers then divided the sample so they could separately look at preschool kids and school-aged children six years of age and older.

The results were completely unambiguous. Among the school aged kids in the study, those who had lived with a dog during the first year of their life were 13% less likely to have been diagnosed with asthma by the age of six, compared with the kids who had not been exposed to dogs at that age. One important finding is that even those children, who might be presumed to have a genetic predisposition toward asthma (because one or more of their parents had been diagnosed with the problem) showed a similar decrease in the likelihood that they had symptoms of the disease. These benefits seem to take time to show up, since the data from the preschool children show no difference between the kids that had been exposed to dogs and those who had not.

Protection from asthma symptoms seems to be even greater for children who've been exposed to farm animals in the first year of their life. In this case the preschoolers showed a 31% reduction in asthma diagnoses while the kids who are six years old and older showed a 53% reduction.

It is important that the dog be in the household during the first year of life and before the child has ever shown any asthmatic symptoms. It is well-established that bringing a dog into the household where a child already has developed the disease can produce bad effects.

Why does the presence of dogs in the home produce such a protective effect? The researchers say that they don't know for sure what explains a link between early exposure to animals and a reduced risk of asthma. It might be due to a single factor, or more likely, a combination of several factors related to dog ownership lifestyle or dog-owners' attitudes, such as kids exposure to household dirt and pet dust, or increased time spent outdoors with their pet. However there is also an alternative set of suggestions which are sometimes presented under the label of the "Hygiene Hypothesis." This theory suggests that being exposed to bacteria, dust, and dirt early in life is crucial for developing a healthy immune system. The suggestion is that the immune system must be challenged early in life in order to be strengthened to the degree that allergies and asthma can be fended off in later life. Simply put, exposure to the typical dust and debris that dogs stir up in a household may in the end be healthier than living in a sanitized pet-free environment.

In an interview Dr. Fall summarized her conclusions saying, "My take-home message from this study is that parents at this point do not need to worry about keeping their dog or getting a puppy when expecting a baby for fear of asthmatic disease. I want to be clear that this recommendation is valid only for families without a child already having allergies. If they already have a furred-animal-allergic child, we do not recommend them to get a furred pet."

Stanley Coren is the author of many books including: The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome

Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission

Data from: Tove Fall,  Cecilia Lundholm, Anne K Örtqvist,  Katja Fall,  Fang Fang, Åke Hedhammar,  Olle Kämpe,  Erik Ingelsson,  Catarina Almqvist (2015). Early Exposure to Dogs and Farm Animals and the Risk of Childhood Asthma.JAMA Pediatrics. 2015;169(11):e153219. doi:10.1001/jamapediatrics.2015.3219