1.5 years ago, my sister adopted an outside cat, Angel. She is a moo cow, in all ways. Shortly thereafter, they found a 'puppy. L & B, it was (and still is!) a GSD. Her name is Sera. Sera uses Angel as a PILLOW! I have pictures to prove it!!! Then, along came a rottie pup....these have got to be two of the world's largest dogs now (informal survey results). They added two more cats. All of them get along very well, and you have to admit, these can be aggressive doggies. The rottie (now tipping the scales at 90 lbs) plays with the kitties....

Chris, it CAN happen. Good luck, and keep the faith.