This is what I use in my puppy room and I have a smaller one in Earl Greys litter box room. They really serilize the air and give it an almost chlorine smell to the air. Any of the air purifirers are pretty pricey. Lowes or some place like that may have more inexpensive ones;
Austin Air Pet Machine
Perfect for those who suffer from pet related allergies and need to remove dander and odors from the home.