5 feet is not tall enough IMO to help make the distinction between cat and dog in this. Many big dogs can do a five foot fence in a leap however dogs in general would rather go under or through, cats over. A domestic dog has less incentive to leave however and can be caught still there often playing or resting. Cats are not comfortable and leave.
Bobcats and especially Lynx have very large paw prints for the size of cat since they are adapted to walk on snow. Dog prints have claw marks and are in straight lines generally across areas, cats don't have claw marks and wander around things, sticking to edges more than boldly crossing an open area.
If you can borrow a hunter or trapper's camera, or get a motion activated security camera cheep I would, you can't stay up all night always and you have no idea when it will be back. If you have power in the coop and a wireless internet connection close enough there are cameras that will load pictures to your computer too.
ETA hot wires do not work on top unless you have a ground wire next to it. Connect that to the unit's ground.