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Asthma

25 December 2018

A 'hypoallergenic' dog? You may be barking up the wrong tree

Malmros cautioned that the study findings can't prove that certain breeds cause asthma or allergies, only that there is an association.

Do so-called hypoallergenic dogs really protect you against asthma?

Many dog-lovers believe it, but Swedish researchers found no evidence that "allergy-friendly" breeds – such as poodles and miniature Schnauzers – actually lower the risk for the wheezing lung disease.

No evidence for 'hypoallergenic' dogs

Previous studies have shown that growing up with dogs can reduce a child's asthma risk, but researchers wondered if the type of dog makes a difference. For this study, they wanted to see if variables such as sex, breed, size or number of dogs affected the risk of asthma and allergy during a child's first year of life.

Researcher Tove Fall of Uppsala University in Sweden led the study. She's a senior lecturer in the department of medical sciences.

"The sex of the dog can affect the amount of allergens released, and we know that uncastrated male dogs express more of a particular allergen than castrated dogs and female dogs," Fall said. "Moreover, some breeds are described anecdotally as 'hypoallergenic' or 'allergy friendly' and are said to be more suitable for people with allergies, but there is no scientific evidence for this."

For the study, the researchers collected data on 23 600 children, born in Sweden between 2001 and 2004, who had a dog in their home for the first year of life. The investigators linked that information with two dog owner registries that classified dogs by sex, breed, number, size and claimed "hypoallergenicity".

The researchers then compared the dogs' characteristics to the risk of asthma and allergies or the prescription of asthma or allergy drugs for children at age six. They took into account known factors that could affect risk, including parental asthma and allergy, geographical location and number of siblings.

No increased risk for asthma

The analysis revealed that 5.4% of six-year-olds had asthma. And children who had female dogs had a 16% lower risk than those with male dogs.

But living with a male dog did not put kids at higher risk than having no dog at all, the findings showed. And children in families with two or more dogs had a 21% lower risk of asthma than those with just one.

Kids whose parents themselves have asthma or allergies more often had dogs described as "hypoallergenic" than did other children (12% versus 8%), according to the report.

Exposure to these breeds was tied to a 27% higher risk of allergy, but no increased risk for asthma.

Study co-author Catarina Almqvist Malmros is a professor in the department of medical epidemiology and biostatistics at the Karolinska Institute in Stockholm.

Malmros cautioned that the study findings can't prove that certain breeds cause asthma or allergies, only that there is an association.

"The likely explanation for this higher risk is that families with a history of allergy to furred pets more often choose these dogs, and also that 'allergy-friendly' dogs do not in fact release less allergens," she said in a university news release.

The report was published online in the journal Scientific Reports.

Image credit: iStock

 

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Asthma Expert

Professor Keertan Dheda has received of several prestigious awards including the 2014 Oppenheimer Award, and has published over 160 peer-reviewed papers and holds 3 patents related to new TB diagnostic or infection control technologies. He serves on the editorial board of the journals PLoS One, the International Journal of Tuberculosis and Lung Disease, American Journal of Respiratory and Critical Medicine, Lancet Respiratory Diseases and Nature Scientific Reports, amongst others.Read his full biography at the University of Cape Town Lung Institute

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