I've often heard it said that owning a dog can strengthen children's immune system, but this is the first time I've read of an actual research project that shows it's best if the dog lives in the house with the family.
Here's a quote from news.com.au:
Allergy experts from Melbourne's Murdoch Childrens Research Institute studied more than 5000 babies and found those with young siblings and infants exposed to a dog inside the home were less likely to develop an allergic reaction to egg...
Lead researcher Dr Jennifer Koplin said the risk of developing a food allergy seemed to be a combination of genetic and environmental factors.
She said the immune system evolved at a time when people were exposed to more bacteria in food and the water supply, and infections through crowding and larger families.
Dr Koplin said it was possible developing infants were now not exposed to the right environmental factors to teach their immune systems how to react appropriately.
"They are reacting inappropriately to something that they should be able to tolerate which is in this case, food allergens, or food proteins," Dr Koplin told AAP.
The research suggested the protective effect of a family dog on egg allergy could be due to exposure to endotoxin, a type of bacteria.
Dr Koplin said endotoxin stimulates the immune system to attack bad bacteria and in doing so, is distracted from attacking harmless things in the environment like foods.