Yes, I use a human treadmill...most do. Every one of Cesar's shows that I have seen when Cesar gets the dog on a treadmill, it is one the people were using...Cesar often asked if they would mind letting the dogs use it. I have yet to see Cesar working with a canine treadmill. (doesn't mean he hasn't....just not in any of the many episodes I have watched).
The biggest difference (that I am aware of) between the dog treadmills vs the human ones (other than price, of course), is that the dog one comes with things at the sides to prevent the dogs from going off the side. Some people have used baby gates. I personally had the treadmill close to one wall, and had a chair on the other side. Now that Chance is so good with it, I don't need the chair anymore.
Another thing to watch for is the belt. Make sure that there is no area where the sides of the belt is exposed when it's running. IF it does have the side of the belt exposed, if the dog's paw got too close to the side, it could make for one very nasty "paper cut". The one I have, there is a little lip on either side, that covers the side of the belt, so it is virtually impossible for the dog to get his paw cut, even if he did step on either side.
I've been told by a Lab breeder at one time that treadmills are great, but ideally the treadmill should be 6 ft long (for a Lab). Smaller breeds would be fine with a smaller one. I'm not sure about the giant breeds tho!