December 06, 2018

Hypoallergenic Dogs and Childhood Asthma/Allergy Risk

Digging deeper into the association between dog ownership in the first year of life and childhood asthma and allergies.
By Amanda Carrozza
Dog Childhood AsthmaMany pet owners believe that hypoallergenic dogs offer a road to pet ownership that will not be blocked by asthma or allergy. But a group of Swedish researchers is challenging that notion—particularly when it comes to young children.

In a study led by Tove Fall, PhD, DVM, a senior lecturer at Sweden's Uppsala University, researchers collected data on all children born in Sweden between 2001 and 2004 who had a registered dog in their home for the first year of life (n = 23,585). The investigators linked population registry data with data from 2 dog owner registries that classified dogs by sex, breed, number, size, and so-called hypoallergenicity. The goal: to determine whether variables such as sex, breed, size, or number of dogs in the home affected the risk of asthma and allergy during a child's first year of life.

"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," Dr. 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.”

Using logistic regression models, the researchers examined the association between the dogs' characteristics and the children’s risk of asthma and allergy diagnosis or medication prescription at age 6. Statistical analyses controlled for confounding factors that could affect the risk of asthma/allergy development, such as parental disease, geography, and number of siblings.

Asthma Risk Reduced By Dog Ownership
The investigators found that 5.4% of the children had asthma at age 6. Children who had female dogs had a 16% lower risk than those with male dogs. Living with a male dog, however, did not put kids at higher risk than having no dog at all. In fact, children from families with 2 or more dogs had a 21% lower risk of asthma than those with just 1.

Role of Hypoallergenic Pets
The investigators found that kids whose parents have asthma or allergies were more likely than other children to live with a dog described as "hypoallergenic" (12% vs. 8%). Some of the most popular breeds deemed hypoallergenic include poodles, miniature Schnauzers, bichon frises, and Portuguese water dogs. Childhood exposure to these breeds was tied to a 27% higher risk of allergy, but no increased risk of asthma.

RELATED: Ultimately, the authors concluded that the findings cannot 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," said Catarina Almqvist Malmros, MD, PhD, coauthor of the study and professor at the Karolinska Institute in Stockholm.

Additional studies are needed, the investigators said, to “monitor differences over time, measure the risk of allergies using biomarkers, and take account of the microflora.”

 

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