Chihuahuas. I nearly run over them on the way home because they suddenly run into the street. UGH. Ugly little rats, they are.
The worst dog encounter I had was a with poodle mix. She was on the sidewalk and barking in a frightened way so I dismounted from the bike and tried approach her and calm her down enough so I could grab her leash and find her owner. I was about to catch her when she suddenly ran into the street. I ran after her (the street was clear on one side) but she got to the other side and got run over right before my eyes before I could catch her. Dammit, it almost made me hurl. The driver of the car didn't stop, and I was left standing on the island in the middle of the street, watching the poor dog scream but unable to get to her because of the traffic. After a while, I just gave up and turned back.