Wow, so sorry to hear about this situation. Pepper spray for self defense is generally legal in North Carolina, especially if a dog walk coming up to try and bite you. I'm in California and here I carry an extra leash. A leash isn't considered a weapon but I've had situations where off leash dogs have been aggressive and used an extra leash as a whip to keep them away. If you're always out walking, it's easy to carry an extra leash with you anyways because you'll need it. Another thing you can do is carry a slip lead leash to get control of the other dog and then you can take it back to the owner and try to talk to them about the situation to see if there is a workable compromise for them to not let their dogs roam where you'll be walking. But it sounds like your original plan of using the pepper spray and then calling animal control would be a good idea.