I keep them in a dog cage thing that is quite large (I use the largest type, 48") It's lined with hardware cloth and I use blue tarp to cover them up at night. But wouldn't fabric suffocate them?
Fabric breathes better than tarp material. So you don't have a coop at all?
Do they stay in the dog cage all day long? Do they have a run? How many do you keep in the dog cage? What breeds? And how big exactly is this dog cage?