Dogs ward off allergies in small children, German experts claim
Hamburg, Germany - Children who are raised with dogs from an early age have fewer common hay fever-related allergies than children from pet-free homes, according to a team of German researchers.
The new findings will raise a howl from an earlier generation of medical experts who cautioned parents about the possible allergic hazards of pet fur.
It used to be conventional medical wisdom to warn parents against owning a dog, if their children showed early signs of hay fever.
But the new study by experts from a range of German universities and institutions came up with evidence showing that early exposure to dog hair in fact helps small children to become less overly sensitive to air-borne allergens such as pollen.
It is almost as though dog hair acts as an inoculation against hay fever, according to the results, published in the European Respiratory Journal.
"Dog ownership in early childhood was associated with a significant lower rate of mixed pollen and inhalant sensitization" in children under age 6, says the author of the paper, Dr. Joachim Heinrich, who headed the joint study by the German GSF National Research Centre for Environment and Health, the Institute of Epidemiology and Ludwig-Maximilians University of Munich, Germany.
The study cautioned, however, that there were no other observable health advantages to dog ownership. Nor did any benefits come from just occasional exposure to dogs during childhood. Also, there was no reduction in allergies associated with household dust mites.
"Regular contact with dogs during childhood without ownership was not associated with the health outcomes," he writes. "No associations were found between house dust endotoxin exposure during infancy and sensitization outcomes."
The intriguing question was why there were no benefits for children who frequently came into contact with dogs but who did not actually have dogs living with them at home.
Dr. Heinrich speculates in media interviews that the presence of shed dog hair in the home may be a contributing beneficial factor. But he says more study is needed.
The studies did not involve children over age 6, he cautions.
"We investigated the association between dog contact and indoor endotoxin exposure during infancy and the development of allergic sensitization and atopic disease up to age 6," Dr. Heinrich writes.
In both studies, information on children's contact with dogs and their allergic symptoms and doctor diagnosed allergic disease were collected during follow-up using questionnaires.
Common air-born allergens such as pollen were measured at age 6. House dust samples were collected at age of 3 months and the amount of endotoxin in house dust was determined.
The studies involved nearly 10,000 children from birth until age 6. (dpa)