My last dog was attacked several times by off-leash dogs, once by a dog the owner claimed was "friendly" after each attack my dog was more fearful and if he saw a dog of the same breed would become defensive and that took a lot of time to resocialize. I staved off quite a few attacks by getting my dog behind me and as the other dog approached saying a very loud, very firm NO! In most cases this would get the other dog to stop. I also would make sure I stayed between the aggressor and my dog if it tried circling around. When I did AC I used to carry a "bite" stick (whis is really just an expandable baton) if a dog would attack you offer instead of your arm, but I found that just by pointing it at an aggressive dog and saying no, would be enough to cause the dog to remain a distance away. You may want to consider carrying a cane or another type item. I also used to recommend people carry an airhorn, it may not always prevent an attack but it will definitely get peoples attention and hopefully get you help.
Speaking as an ACO and about my experience in my own state. You have the right to protect yourself and your dog from imminent attack, this includes harming or killing the other dog. The key word being imminent. If an off leash dog attacks yours the owner should be responsible for any damages, but you have to take them to court if they won't pay AC cannot force them to pay. I also suggest reporting incidents of attack /aggression so that a history can be started with ac even if you don't know who the owner is, just give a description of the dog or a car registration. Leash laws do often allow dogs to be off-leash BUT they have to be under control, my interpretation being at heel at the knee, not 10 feet away, and not approaching other dogs. To be honest I would not attempt to kick an attacking dog, you could very easily get pulled off your feet, the dog could grab your leg you'd be better off with a bite stick that will allow you to keep distance yourself, your dog and the attacking dog. Your dog has the right defend himself BUT chances are the other owner will say your dog was the aggressor (because their dog would never, ever hurt anyone) and again it comes down to a lawyer and court thing.

 Quote: Aaron Myracle

I walk with one of these:

http://www.beretta.com/Defence-Pistols-Carbines/Defence/Compact/84FS-Cheetah/index.aspx?m=82&f=2&id=783

And will use it.

I need to move, I'd be locked up forever walking around with this, but boy it would come in handy!!

BudK is an interesting site. I sorted their closeouts by top rating and got lots of Nazi regalia.

thank you guys

 Quote: Melissa Hoyer

I walk with one of these:

http://budk.com/Self-Defense/21-Impact-Baton

And will use it.

Me too and I have used it!

That is very similar to what I used when doing AC.