Two weeks ago one of my chickens jumped my 5 foot fence and was bitten by a dog. She didn't make it. I have another one, different breed that is routinely escaping. I raised the fence to 7', adding 2' of deer fencing to the 5' existing fence. It failed to stop her. I clipped her wing yesterday. I read its best to clip only one wing or they may develop stronger muscles in both wings to allow them to fly again. It didn't work either. I have a tree in the center of the run, so my next plan is to raise the side where she escapes the most to 10'.
If that fails, I will try to build a partial roof along the perimeter.
Adding a full roof would be difficult, there is a 10' spruce tree in the center. The run is about 15 x 15.