I find it amusing that this thread was started by ladydinj asking if it's ok to leave a soiled wee-wee pad down during the day, and it ended up with giving dogs cheerios.
Anyway, make sure you keep the pad in one place at all times. If the poo is firm, then pick it up with tissue and flush. You should be able to use the pad again. As long as she pottys anywhere else other than her pad when she is out, then don't let her out unless you are holding her on the sofa or playing with her on bare floor. Neve let her go off by herself.