I had a mutt run into my front wheel last week also! I mannaged to maintain control of the bike, unclip my left foot and catch him just behind the ear in round two!
I ride at night some and I can tell you there is nothing like hearing the scraping of claws in the darkness comming up on you with no warning! I make no bones (pun intended) about it! I would use chemical, physical, or electronic wepons on any of them that chase me if I have them! I will also tell you that most dogs don't bother me very much, most of the time I just talk to them and every thing is ok. It's the one that runs into you or clamps onto your ankle that is the BAD DOG!

I have a question here! Has anyone else had a dog run back and fourth in front of their bike to slow you down for the rest of the pack to catch up? I have a mutt on one of my routes that does this every time I come through! I thought about seeing if he does the same thing to pickup trucks!