If you already have a human treadmill a dog can use that too mine does

The reason for using a tread mill is to give a dog the excersice he needs, a beagle for instance should walk upto 25 miles a day if you have a job this would be impossible with a tread mill it is feasible

Illegal? No its a treadmill it doesnt force the dog to get on it,

My dog tells me when he want to go on the treadmill and he loves it