And watch out if they get loose. The local garage dog did and attacked ours as we walked past one evening not long after we arrived. The injury plagued him for the rest of his life, despite 3 operations. The garage dog is still there, tied up, you can't see him, but you hear him, barking away every year getting a little bit hoarser and quieter. Sad all round.
You should have stomped that dogs head in before he got to you and your dog.
The owner of the guard dog is retarded for letting it loose without a muzzle. You should have kicked out of 1st gear and went straight to 5th and this would have been avoided.
I know myself I would destroy a dog if it came near me. I have no sympathy for any owner who is too dumb to think everyone likes the risk of being bitten by an unknown dog.