You could put some wire in it and attach it to the bottom of the inside of the coop and put some dirt over the wire and even put a wire shirt around the outside bottom of the coop and run to keep predators from digging.
I have electric wire around my coops and pens. The predators know it's there. I also have concrete under the pens gates and netting covering the pens. If there is a way to get in and get to the birds a predator will usually find it. There are some of the more vulnerable places that I dug a...