Babies who grow up with a pet dog are half as likely to develop childhood asthma – but having a cat makes no difference, a study suggests.

Researchers analysed dust samples from the homes of 1,050 tots aged three to four-months and tracked them until they were five years old.

Over this period, 6.6 per cent were diagnosed with asthma.

Research has shown that infants who encountered higher concentrations of the allergen Can f1, which originates from dog skin and saliva, experienced a 48 percent lower chance of developing lung issues compared to other infants.

They also appeared to have better lung function – as measured by a test to see how much air they could blow out in one second after a deep breath.

This beneficial effect was most pronounced in children genetically predisposed to poorer lung performance, according to scientists at the Hospital for Sick Children in Toronto, Canada.

Conversely, no similar protective benefit was observed in children exposed to dust carrying cat allergens or bacterial endotoxin, a bacterial surface molecule.

Babies exposed to higher levels of the allergen Can f1, which is shed in dog skin and saliva, had a 48 per cent lower risk of developing asthma

Dr. Jacob McCoy, who discussed his research at the European Respiratory Society Congress in Amsterdam, stated: “In our study, we looked into allergens from pets, specifically dogs and cats.

We discovered that, although cat allergens showed no connection, exposure to dog allergens correlated with enhanced lung health and a decreased asthma risk.

‘We don’t know why this happens; however, we do know that once a person becomes sensitive to dog allergens, they can make asthma symptoms worse.

This indicates that early contact with dog allergens might prevent allergen sensitization, possibly by modifying the nasal microbiome—the blend of microbes within the nose—or by impacting the immune response.”

‘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 added: ’Asthma is a very common chronic respiratory illness in children, with the highest rates in the first four years of life,’ said.

‘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.’

Commenting on the study, 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, said: ‘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.’

Sarah Sleet, chief executive at Asthma and Lung UK, said: ‘Previously a lot of advice for children who wheeze or are at risk of developing allergic asthma has been to remove pets from the family home.

‘So, this new research suggesting a dog in the home could actually reduce the risk of developing asthma is fascinating, although we will need more research to understand what it is about dogs that makes the difference.

‘What this research highlights, however, is a much wider problem in respiratory research.

‘We just don’t fully understand the causes of asthma, how you can reduce your risk of developing asthma and how it can be treated if you do develop it.

‘Decades-long underinvestment has left lung research on life support.

‘Urgent action is needed to increase investment into lung research to give everyone fighting for breath a future.’

It comes as researchers at the congress presented information on new technology which could contribute to earlier diagnosis of lung cancer.

Delegates were told that a new robot-assisted bronchoscope can reach and take samples of very small tumours growing in hard-to-reach parts of the lung, offering the possibility of finding tumours at an earlier stage when treatment is easier.

Researchers put the new technology, which is used alongside a CT scanner, to the test among 78 patients with abnormal lung growths.

Half were given the new kit and half were treated as normal.

Using the traditional technique, doctors were able to reach and take a biopsy for 23 per cent of the tumours.

And using the robot-assisted technology, which costs around one million euros, doctors were able to reach and biopsy more than 84 per cent of the tumours.