While I await the 7D replacement (didn't think the wait would have been this long) I must be content with the 40D's ai-servo. It isn't the best but with a little luck and being in the right position you can catch really fast moving subjects like this.
The subject is in full-stride with both hind legs in the air. The head is in an aerodynamic position (when it is going fast). Notice the position of the two other legs, one is still facing me so the subject has just changed direction likely swinging its hips to the right (from my pov) chasing another of its kind. Not only are they fast but can change direction on a dime.
Canon 40D and 70-200 2.8L and 40D. Thanks for looking.
I know you mean well but please do not embed my images into the forum. Thanks for respecting that.