Babies growing up around dogs are less likely to develop asthma, but exposure to cat allergens does not have the same protective impact, researchers have suggested.
The Independent reports that a study – by a team from The Hospital for Sick Children in Canada (affiliated with the University of Toronto) – found that children exposed to dog allergens in their home had 48% less risk of developing asthma by the age of five, compared with other infants, and also had better lung function.
The protective effect was even stronger for babies who were at higher genetic risk of worse lung function.
Strangely, feline allergens did not offer the same protection.
For the study, the scientists had 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.
The 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 presented their work at the European Respiratory Society Congress in Amsterdam this week, said that indoor allergens were an important risk factor that could potentially be changed, to reduce asthma.
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.
He said while it was unclear why exposure to dog allergens improved lung function, once a person becomes sensitive to dog allergens, it can make asthma symptoms worse.
“This suggests that early exposure ens 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.
“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 this was good news for families with dogs, but more needed to be known about the connection and how living with pets affected children’s developing lungs in the long term.
“This study suggests that babies who grow up around dogs may have a lower risk of developing asthma, which 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.”
Abstract not available
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