The trick is to be able to size up the dog quickly. I have a rating system.
1. Playful dogs. These dogs are just chasing you for fun and would lick you face if they could. Unfortunatley, they can cream you if they run into your front wheel. Dodge and holler seem to work well.
2. Working dogs. Most dogs are just doing the territory thing. They have no intention of doing anything serious. A squirt from a water bottle usually sends them running. Worst case, you stop and spit on them. Most riders never run into anything worse than this.
3. Natural born killers. There is a very small percentage of dogs that are very serious about "getting" you. They tend to be smart. They have a plan. Sometimes they are silent, because they don't want you catchin on. They know trigonometry (vectoring). A water bottle or harsh language is just going to rev these boys up. Stopping may help, but maybe not. You should have a plan for this worst case scenario. Frame pump, spray, etc. These dogs are rare but they exist, I assure you.
If you know your route, and know where the dogs are, take advantage of the geography (hills) to give yourself an advantage. And work on your sprint. Adrenaline is your friend.