[Hawke]

Originally Posted by Inertia

It would probably be best to not carry weapons that are illegal.

That being said, you should be able to find a decent defence pepper spray in any hardware, or sporting goods store, hell Wal-Mart has some in their sporting goods section.
A simple pocket knife may be a solution as well.

In case you are attacked by a domestic animal however, all you would need is your hands.
Assuming that the animal has one of your arms and is causing harm or you are in fear for your life, simply use the pointer and middle finger of your free hand and push them through the animals eye.
If the animal persists pop the eye ball and push through to the brain. That should either cause the animal to release or die depending on how much presure you create.

I don't think he's planning on letting a bulldog get that close.

Edit: Bulldog's will rip your arm off but they usely go for the face. Also about the domestic animals thing, your hands aren't going to do anything against a rottweiler or bulldog. Your arms with be in their mouth or on the ground, not connected to your arm.