Further east of Denver and the springs, the more p/dogs there are.
Just look responsible and safe. Most ranchers will allow shooting out in those parts.
Try around Limon, Joes, or most any direction down the dirt roads, they run all over the
country out there. When you see a batch, go to the nearest ranch house and ask.
IF they don't own the place, they'll know who does and many times will still tell you to
have at it. OR will call the owner and ask, or direct you to where the owner is/lives.
It's not very hard to find a place to shoot p/dogs, IF there are some. and there's always
some somewhere on the plains. Just don't ask to shoot among the cattle unless you happen
to already know the rancher and have permission to.
Good luck, and take plenty of ammo.
George