I just have a pretty secure run and don't have a door on my coop at all. They come in and out as they please. In the summer I just leave all the little "hatches" open - it's almost like roosting outside - no hardware cloth or anything over the vents. The bottom of the run is 3 feet high of hardware cloth and the rest is chicken wire. But, I don't have all the varmints a lot of you have. The only thing I really have to watch out for is coyotes, hawks, and skunks. Our yard is fenced in half and during the day when we are home, the dogs stay on one side (mostly just to keep them from pooping everywhere), but at night, I open the middle gate and our dogs roam the entire yard keeping any other critters out. Our dogs would eat the chickens if they got the chance but they don't actively try to get into the run and they don't dig. Most of the time they ignore the chickens and ducks. However, they will kill anything that comes into our yard so they are my night patrolers just in case we get something that tries really hard to get into the run.