This is what I would call a "duvet cover" for a dog bed.  Why not repurpose old pillows and stuff into this cover.  Their website says they are 100% cotton but the label doesn't indicate the fabric.  It has a 4" gusset and when filled will be 27" x 36" x 4".  It fits dogs up to 70 lbs.  You can even use this to cover an existing bed. 

It is washable and has a zippered opening.  

$4 will be added to your winning bid to help with cost to ship.

Lois to ship.