The 'Everything' Discussion Forum

My older dog is a terrier mix. I'm not allergic to her. She sleeps at the bottom of the bed. Our new dog is a shitzu mix. If she comes up on the bed, I start to feel itchy and my nose starts to run. How can you be allergic to some kinds of dogs and not others? I feel like Cinderella's evil stepmother making her sleep on a pillow while the other crashes on our bed.