I have a potty-training related problem of a different kind. My dog Maddie, a border collie mix, is extremely smart and well behaved. She hasn't had an accident indoors since the day I brought her home at 8 weeks of age and she's 5 years old now. However, she's also extremely fearful and submisssive. If she hears thunder she won't go outside for several hours until after it has passed. Noises like fireworks and loud car engines have similar effects. If I force her to go outdoors, she panicks and digs at the house even if I stand in the yard with her. My concern is that sometimes she will refuse to "go potty" of any kind for nearly 24 hours- this cannot be healthy! Any suggestions?