Unless its a grayhound, it can't run more than 30 mph in a sprint. Since this is the 41, and everybody's average speed is 45 mph, you can slow down and still outrun the dog.

The best thing to do is to use your situational awareness - that thing you need to have anyway - and let it tell you the next move. If there are a lot of dogs on your routes and you aren't used to being around them, you should make friends with people who have dogs, and join them to walk the dogs, especially to dog parks. It's usually pretty easy to tell whether a dog is running at you because it's excited to see somebody or because it's vicious and wants to attack. Jerky, frightened, or aggressive movements will only escalate the situation; if a dog is just patrolling its turf, don't "tell" it to attack you.