You need to get some Muzzle (doggie mace) to carry with you on your walks. Next time it could be a more determined attacker who won't be scared off by a can of pennies. We have heard too many stories like yours that ended tragically.
I fractured my pelvis several years ago when a loose dog came after Lady. I have had a can of Muzzle attached to the handle of my leash ever since.
Amazon.com: Mace Brand Muzzle Dog Repellent...