Tie your horse to the bumper of your car then hit the expressway........if it can't keep up then tie it to the median with a 50 ft. rope till you get back. Whatever happens certainly ain't your fault.....
His livestock, his problem. My cousin walked his show streers with his tractor. Today they probably use a four wheeler.
Got enough money you can always by an electric walker, http://www.horsewalkers.com/free_flow.html