My agility club keep trying to get me to do flygility with the Dougal baby. It's a lot like fly ball except you do 3 / 4 hurdles and a tunnel then hit the ball flinger thingy and then race back through the tunnel and over the hurdles - they tell me that they do have smaller tennis balls for smaller pooches. There's a few YTers that do agility and I'm sure they can tell you about flyball in the States. Try gooogling it