Well...how bad are they? If they are just a bit dirty, or have some pet hair on them? Then, hand baste around the quilt sandwich and let it soak overnight with some cool water and mild laundry detergent, rinse thoroughly and lay flat to dry. After the quilt is quilted, bind and wash again. You may try some of the kind suggestions above concerning mold. That's another issue. I would not send anything with mold on it to the long-armer.
Good luck!
~ Cindy