It may be that you won't agree with me, but in my mind "candid" implies a photograph of a person at a candid (i.e. unaware of the camera) moment. So, to that way of thinking, this doesn't really meet the challenge.
It is hard to say if the dirt these guys are throwing up is distracting or if there is a color cast/over saturation problem here. To begin with, this is a great stop-action capture! Almost every dog is in focus and yet the foreground (rabbit) is slightly blurred which means you chose just the right dog to focus on. Your crop choice is great, leading the eye from top right to left to bottom as the race is leading the viewer. Your border choice is not annoying or overpowering and the shot's color scheme combined with it give a 50's feel to the composition.
Unfortunately, I see nothing candid in this entry. Yes, candid can be used with animals, but this is a sporting event (I won't get political on this one), and the shot is stop action, emotion: excitement, anticpation. I commend your composition as technically high, deduct for what seems to be a bluish/neon color cast and cannot find the link to the challenge. This leaves this entry at a 3.
Action shots are tricky but you seem to have some experience...or great luck. Either way, I like the angle on the shot--how you get the rabbit in the photo.