Big Paws Only Dog Forums

I've tried everything! Persephone is usually very responsive to treats and petting, but when we are outside the house she is only focused on the wonderful smells and sights of the streets. You can forget about regaining her attention if she sees another dog, and once we are in the vecinity of the dog run... Well, let's just say that it takes a lot to hold an 80 lbs. dog back, and she's not even full grown yet!

I've tried positive reinforcement, carrying food in my hand next to me (but she loses interest pretty fast.. there's so many distractions in a city!), and even stopping completely until she gets closer and the leash is slack (but she just goes back to pulling as soon as we start walking again). The only thing that she actually obeys me on outside is when I tell her to sit at the street corners before crossing. She's relatively good with her "come" inside the dog run (and I'm amazed at even just that because there's other dogs to pay attention to). I don't know what else to try. Any suggestions?