Babies and dogs are not only adorable together, but raising them alongside each other may lower the risk of those babies developing asthma, according new research by a team in Toronto, Canada.
Dr. Jacob McCoy from The Hospital for Sick Children will present their research – led by Dr. Makiko Nanishi – at the European Respiratory Society (ERS) Congress held over the coming days in Amsterdam, the Netherlands. They found that exposure to dog allergens in the home lowered the risk of children developing asthma by the time they were 5 years old.
“Asthma is a very common chronic respiratory illness in children, with the highest rates in the first four years of life,” said McCoy ahead of the conference, which began Saturday. “It is caused by complex interactions between genetic factors and the environment, including infections, allergies and air pollution.”
According to U.S. Centers for Disease Control and Prevention data, more than 4.5 million children in the U.S. had asthma as of 2022, or 6.2%. More than 22 million adults also had the condition, or 8.7%. There is no cure for asthma.
That makes it one of the most common long-term diseases of children, per the CDC. Asthma affects the lungs and can causes wheezing, breathlessness, chest tightness, and coughing at night or early in the morning. Those with the condition can also have asthma attacks. During these attacks, the body’s airways swell. This makes passages smaller and makes it harder for air to pass in and out of the lungs, allowing mucous to clog the airways. In rare cases, asthma can lead to death.
Per the National Lung, Heart and Blood Institute, the exact causes for asthma are unknown and may even be different from person to person. In some cases, it can be caused by the body’s natural defenses against germs and sickness reacting strongly to new substances.
“Asthma usually starts during childhood when the body’s defense system is still taking shape,” the institute explained. As McCoy noted, viral infections, family history and environmental factors (including smoke, dust mites, mold and pets) can all play a part in the disease.
To study whether early exposure to pets had an impact on children, The Hospital for Sick Children research team analyzed a group of 1,050 children who were part of the Canadian CHILD cohort study. Specifically, they analyzed samples of dust from the children’s homes taken when they were between 3 and 4 months old, measuring quantities of three potential allergens: Can f1 (a protein shed in dog skin and saliva), Fel d1 (a protein shed in cat skin and saliva) and endotoxin (a molecule on the surface of bacteria).
“Children spend most of their time indoors, so in this research we wanted to study allergens in the home,” McCoy explained. “These are an important risk factor that we could potentially alter to reduce asthma.”
When the children were 5 years old, they were assessed for asthma by a doctor. Assessments included measuring lung function according to how much air they could blow out in one second after a deep breath in, as well as blood samples to check genetic risk factors for asthma and allergies.
Babies exposed to higher levels of the dog allergen Can f1 had around a 48% lower risk of developing asthma by age 5 compared to other babies, the researchers found. They also said that babies exposed to dogs had better lung function.
“This protective effect was even stronger in babies who were at higher genetic risk of worse lung function,” according to the European Respiratory Society.
Cat exposure on the other had did not seem to have a protective effect for babies, the research found. Likewise, exposure to bacterial endotoxin didn’t have a protective effect.
McCoy said the reason why exposure to dogs has a protective effect on babies’ lungs is not yet clear.
“We do know that once a person becomes sensitive to dog allergens, they can make asthma symptoms worse,” he said. “This suggests that early exposure to dog allergens could prevent sensitization, perhaps by altering the nasal microbiome – the mixture of microbes living inside the nose – or by some effect on the immune system.”
People who have asthma and dog allergies or other pet allergies should limit exposure to the animals they are allergic to. Families can find new homes for pets or keep them out of bedrooms, keep them washed, use air cleaners with HEPA filters and use allergen proof mattresses and pillow covers.
In the U.S., nearly 60 million households already have dogs in their homes, according to the American Veterinary Association. In 2023, the National Association of Realtors reported that there were actually more pets in American households than children. While the new research scores a point for dog lovers, McCoy said more research should be conducted going forward.
“Our findings highlight the potential protective role of dog allergens, but we need to do more research to understand the link between early-life exposure to dog allergens, lung function and asthma during early childhood,” he said.