Dogs linked to asthma

Asthma-suffering children may find their respiratory problems are worsened if they have a dog in the home, medical experts have warned.

A report published today in the Environmental Health Perspectives journal has established a link between the presence of a dog and higher levels of responses to air pollution among children.

Chronic coughs, higher phlegm production and increased bronchitis risk were all measured by scientists from the University of Southern California (USC), who found that those children who lived with cats or with no pets at all did not suffer from these symptoms to the same degree.

The precise nature of the link between the presence of dogs and greater responses to air pollution remains unclear. Professor Rob McConnell argues that the key could lie in a part of the cell wall of bacteria, endotoxin.

“If an allergen were enhancing the lung’s response to air pollution, we’d be more likely to see an association with cats,” Professor McConnell said.

“But in this study we see an effect of air pollution in homes with dogs, so we think endotoxin exposure is a more likely explanation for our results than allergen exposure.”

Despite this he warned that this theory was not supported by scientific evidence and suggested that further research be carried out to check that indirect factors be ruled out.

Children with dogs could become more exposed to air pollution because they walk their dogs and therefore take more exercise outdoors, Professor McConnell suggested as an unsubstantiated alternative theory.

The European Pet Food Industry organisation Fediaf estimates that there are around 6.8 million dogs in Britain, while the National Asthma Campaign claims that about 1.4 million children are currently being treated for asthma throughout the UK.

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