When out walking with a dog you should have some pepper spray on you in the event another dog attacks your attempts to attack your dog.
If the dog does attack your dog you should spray the other dog with pepper spray but you might get some pepper spray in your own dogs eyes but that will wash out and it could save both your life and your dogs life.
After the dog attacks your dog you should call 911 or the animal control to report the dog attack and if you've been bitten by a dog you should report it to the police.
Then you may need to sue the dogs owner for attacking your dog and for attacking you if they did do so.
Owners of dogs are responsible for their dogs and have to keep them under control and if they do not then they can get into trouble and be sued.
If your dog does get attacked and injured you should treat them and calm them down and if needed take them to the vet.