Dirt Dog aka Earthdog.
Animal Planet aired an indoor competition with above ground mazes so you could see the dog hunt for the rat/rodent.
I have to admit that I found this the funniest and most entertaining show around. You literally could see the thought process of the dog as he hunted for the scented ball.
I believe the actual outdoor event is called Earthdog. I have not seen any of the competitions since that one airing.
I'll choose flyball and dirt dog over the breed shows anyday.