That is a concern actually. And even thought the cat house is only about 15-20 feet from the house, I do want to get something around the bottom edge of the fence. I was thinking of just nailing wood, but that would just stabilized the fence for what ever wanted to dig under. So I think putting large rocks around the edge would deter something from digging, as the rocks would shift and fall on them. Either that or a line of hot fence....
One whole hot box for only about 60'? Hahaha!
As of right now though we are working on getting up a proper "back yard" fence. The back yard would of course, include the cat house and yard inside it. So that would add another fence line, along with our outer perimeter fence, in the way of a coyote.
We are also planning on putting up an alley way between the "back yard" and the horse pasture too. Yet another fence. That'll have to be on hungry mutt that wants to get to my cats. An hopefully make enough noise by the time it is right here that we will know. And then it won't exist any longer. ;)