Thank you everyone for your help! These are actually not dog quilts per se, but quilts that we use on the couch, our bed, etc. And when people say their dogs aren't allowed on the furniture I say if you come to our house you would think our dogs are not allowed on the floor!
I do have lots and lots and lots of denim squares cut to make a quilt for the bed in our camper because I felt like that would be better when the dogs are kinda getting dirty. But other than that I usually use cotton. I can see where more complicated patterns would cause issues with bulk and throwing off the design. We have had a couple come apart (not ones I made) so I'll keep my fingers crossed!