If a dog runs at me, I usually talk to him/her - sometimes I even stop to play.
You can never have too many friends and dogs are much better friends than most people.
Most of the time dogs chase you to play...don't show fear, talk to them or command them "NO!", and you'll be fine.
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"Let us hope our weapons are never needed --but do not forget what the common people knew when they demanded the Bill of Rights: An armed citizenry is the first defense, the best defense, and the final defense against tyranny. If guns are outlawed, only the government will have guns. Only the police, the secret police, the military, the hired servants of our rulers. Only the government -- and a few outlaws. I intend to be among the outlaws" - Edward Abbey