http://allergies.about.com/od/specif...dogallergy.htm
There are several allergens associated with dogs. Saliva & hair mainly. You may read that there are dogs that are hypoallergenic. Not really. My daughter has asthma and she is allergic to animal saliva (see above link). I'm allergic to the fur of dogs but not to yorkie/maltese hair. I get all clogged up & sneezy when I'm around a shepherd or spaniel. Like cats, in people with severe allergies to the animals, putting the dogs in another room will usually not help. My grandson had an asthma attack after being in our neighbor's back yard for an hour at a picnic last summer. They have a golden and 2 border collies and the dogs were in the house the whole time but the allergens were in the yard.
http://allergies.about.com/od/animal...oaller_dog.htm
here's a list of least allergen dogs