i think its called the biker dog...simple little frame attaches to bike; a rubber rod attaches short lead to dog to frame.

I like that it puts her a little behind....and I use it on the left because it's away from the chain andit is the side on which my dogs always walk with me...

If you look at my squidoo page...I talk about some of these attachments. I actually have 2 I would sell.
One attaches to the seatpost and a hollow tube with a spring in it attaches the dog.
The other is a steel tube that also attaches at he seat stays and puts the dog behind the bike.e