Babies who grow up around dogs are less likely to develop asthma, new research has found.
A study by a team from The Hospital for Sick Children in Canada has found that small children exposed to dog allergens in their home had a lower risk of developing asthma by the age of five, but exposure to cat allergens did not have the same protective impact.
Babies who were exposed to higher levels of dog allergen had around a 48 per cent lower risk of developing asthma aged five when compared to other infants. They also had better lung function. The protective effect was even stronger for babies who were at higher genetic risk of worse lung function.
Scientists analysed the dust samples from the houses of 1,050 children, part of the Canadian CHILD cohort study, taken when they were between three and four months old. For each child, researchers measured the quantities of three potential allergens in the dust: Can f1, a protein shed in dog skin and saliva, Fel d1, which can be found in cat skin and saliva, as well as endotoxin – a molecule on the surface of bacteria.
There was no protective effect discovered for babies exposed to the cat allergen or endotoxin.
These children were then assessed for asthma by a doctor when they were five years old; their lung function was measured based on how much air they could blow out in one second after a deep breath in. They were also assessed for genetic risk factors for asthma and allergies through blood samples.
The researchers, who are set to present their work at the European Respiratory Society Congress in Amsterdam, said that indoor allergens were an important risk factor that could potentially alter to reduce asthma.
Speaking ahead of the Congress, Dr Jacob McCoy said: “Asthma is a very common chronic respiratory illness in children, with the highest rates in the first four years of life. It is caused by complex interactions between genetic factors and the environment, including infections, allergies and air pollution.
“Children spend most of their time indoors, so in this research we wanted to study allergens in the home. These are an important risk factor that we could potentially alter to reduce asthma.”
Dr McCoy explained that while it was unclear why exposure to dog allergens improved lung function, once a person becomes sensitive to dog allergens that can make asthma symptoms worse.
“This suggests that early exposure to dog allergens could prevent sensitisation, perhaps by altering the nasal microbiome – the mixture of microbes living inside the nose – or by some effect on the immune system,” he continued. “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.”
Dr Erol Gaillard, Chair of the European Respiratory Society’s expert group on paediatric asthma and allergy and Associate Professor at the University of Leicester, who was not involved in the research, said that this was good news for families with a pet dog – but more needed to be known about the connection and how living with pets impacted children’s developing lungs in the long term.
“Asthma is the most common long-term condition among children and young people and is also one of the main reasons for children being admitted to hospital for emergency treatment. Although there are good treatments that can reduce or stop asthma symptoms, we also want to reduce risk factors to try to prevent asthma.
“This study suggests that babies who grow up around dogs may have a lower risk of developing asthma. This is potentially good news for families with pet dogs; however, we need to know more about this link and how living with pets affects children’s developing lungs in the longer term.”
