Summarize the following:
If the dog cannot be deterred, you may have to defend yourself. Make sure you enact a strong defensive stance and prepare yourself to fight.  Keep one arm down and use it as a blocker against the dog. If the dog is going to bite you, it's best to receive the bite on your arm so you can still control the dog. Put your other arm behind your back. This will signal the dog to get down and behave. Mace/pepper spray will stop an attacking animal in its tracks, but you may not have tools like this on hand. If you have any liquids at all that can be sprayed or splashed at the dog, it might be worth trying.  Citronella spray is an effective animal deterrent. Mace/pepper spray can also be useful at repelling aggressive dogs. In a pinch, spraying water from a water bottle may stop a dog from attacking. Shoving something towards the dog will act as a shield. The dog will bite your object instead of biting you. Anything you have on hand can be used as a shield: a purse or backpack, a sweatshirt, or even a shoe. If you need to fight, make sure you stay on your feet. Getting pinned on the ground will make it much easier for the dog to hurt you. If you need to strike the dog, try to kick it instead of punching it, as your shoes will provide some protection to your feet.  If you fall or get knocked down, protect yourself. Cover your face, chest, throat, and neck.  Curl into a ball to protect your vital organs. Keep your hands in fists. If you have loose fingers sticking out the dog could latch onto them and do serious damage.

Summary:
Enter a defensive stance. Use chemical repellent if you have it. Shove an object at the dog. Fight the dog.