Keep her well brushed, but if possible do the brushing outdoors, so the dander flies away! As a hound mix, I'm guessing she has a pretty sleek coat ... is that right? Don't bathe her TOO often, though, as that can dry out her skin and make the dander worse.

This part's hard (at least it would be for me) - no doggie on the bed. If his symptoms are bad, she might not be allowed to sleep in the bedroom at all. This might already be happening, but if not, it's time to try that.

If she's allowed on the couch, train her to her own blanket (can be an old one, no big deal) so that she only sheds on that while sleeping - a blanket is easier to wash frequently than a dog or a couch.

Vacuuming consistently is important - does your vac have a good HEPA filter?