PAMELA Phillips grew up with allergies but that didn’t stop her family from owning low-shedding dogs when she was younger. “I never really had allergies to our dogs,” she recalls. As an adult she and her husband got a cat and, a couple of years before their son Liam was born, they added a dog to the family. Things were going pretty well with Phillips’ allergies, until she got pregnant. Her eczema flared and, at the same time, she found herself too tired to take care of the dog properly. Her mother-in-law took the German shepherd-cross as a way to help out temporarily.
Then shortly after Liam was born, Phillips started having asthma attacks. The new mother would wake up at night struggling to breathe. (She saw an allergist who prescribed asthma medication.) Meanwhile, young Liam began to show signs of eczema. When her mother-in-law asked if she could keep the dog, it suddenly seemed a good idea, since the Phillips feared that her son’s allergies would get worse. The couple, who live in a suburb of Nashville, also found a new home for the cat.
Phillips’ thinking is in line with the advice doctors have given out for years: if your family has a history of allergies, you should not expose your baby to pets and their allergenic dander. But what scientists thought they knew about early exposures to things that are allergenic is being turned on its head. Evidence has been amassing in recent years to point to one startling fact: having a dog around a baby in its early life can actually prevent allergies from developing.
In 2011, for instance, researchers at the Henry Ford Hospital in Detroit drew illuminating findings from their long-running Childhood Allergy Study. They showed that, at least for boys, being exposed to a dog in the first year of life reduced the risk of being sensitized to dogs 18 years later by 50 percent. For girls it was less, but having a dog in the house as an infant still made them 33 percent less likely to have an allergy to dogs going into adulthood than those who did not live with a dog.
This “dog protective effect” doesn’t just apply to animal allergies, but to the spectrum of allergic conditions as a whole, from hay fever to eczema, asthma and even food allergies. Many leading scientists are now so certain of this effect that they are moving past “whether” it happens to “why” it happens.
What is it about dogs that turns them into magical protectors of their young owners, helping them to escape allergies? Not only that, but what does this mean for people who are having children today?
ONE OF THE EARLY inklings that dogs somehow play a role in stopping kids from becoming allergic emanated from the Childhood Allergy Study. It was 2002, and the authors were analyzing data of almost 500 Detroit children, whom they had followed from infancy until 6 or 7 years of age. “We had actually collected information about animals in the house because we thought it would increase the risk,” says Christine Cole Johnson, a lead author of the study and chair of Henry Ford’s department of public health sciences.
Instead, it turned out that the children in the study growing up with pets, and in particular, dogs, had lower IgE (or immunoglobulin E, the antibody involved in allergies) to dogs and cats – and also to pollen, dust mites and mold. “They had lower IgE to everything,” says Johnson. “It seemed like a general effect.”
Then in 2009, a paper published from another long-term population study – this time out of Dunedin, New Zealand – showed a similar result. In research that followed more than 1,000 people from birth to age 32, scientists found that living with a dog and a cat (cats are more popular as pets in New Zealand than dogs) lowered the chances that a person developed allergies, and this lasted well into adulthood.
Dr. Malcolm Sears, an epidemiologist, respiratory specialist and professor of medicine at McMaster University in Hamilton, Canada, is a consultant on the Dunedin study, which has been continuing for an astounding 41 years. He says one important thing they looked at in this study was whether parents who owned pets were less likely to be allergic themselves and therefore the children were at lower risk for developing allergies. Interestingly, he says: “That wasn’t the case.”
In fact, there have now been dozens of these “birth cohort” studies around the world that follow children from infancy in an attempt to unlock the mystery of what makes people develop asthma and allergies. Many have collected data on pets in the house, and in a study published in the Journal of Allergy and Clinical Immunology in 2013, researchers pooled the results of 21 such studies to determine whether exposure to pets in utero, during infancy or in childhood had any bearing on whether the child developed atopic dermatitis, or eczema. They looked at households that only had a dog, households that only had a cat, and households with both.
“Dogs alone gave a 30 percent reduction (in eczema) , cats alone was a 6 percent reduction, basically no effect. When they put all pets together, they again showed an effect of about a 25 percent reduction. So it’s really driven by dogs,” says Sears, who was not an author on the paper.
This, he adds, raises the intriguing questions: “What is it about owning a dog? Is it the dog itself, is it the dog allergen, is it the dirt the dog brings into the house? And that’s much less certain.”
Next: Baby, Dog and the Microbiome