The proper name of the sport is Dryland Mushing (as opposed to mushing on snow with a sled) which uses a rig or scooter. Some people refer to using a scooter as Dog scootering.... but that reminds me of something dogs with an itchy bum do along the carpet.

I'm trying to find a link that I can post to describe it better that doesn't contain a forum... but proving hard to find!

Here's one from where I bought my scooter:
http://www.countryhounds.ie/Product.aspx?product=239

The scooter I have is this one:
http://www.countryhounds.ie/Product.aspx?product=144

It really is a sport that most fit and healthy dogs can take part in. Great for running dogs that can't be allowed offlead for whatever reason; though Elroy gets to enjoy plenty of offlead zoomies on days we aren't mushing.

A short video of Elroy mushing in the early days. We started off using his Daddy on a bike as a lure.