My uncles all hunted a lot and had numerous hunting dogs. These were the sacks their dog food came in, big 50-lb sacks. I think there may have been softer fabric on the reverse side, but I don't recall these being really coarse burlap, maybe a coarse cotton.
I can recall my mother buying flour in cotton sacks; they often came with a terrycloth washcloth or dishcloth attached to one end.
We used flour sacks, 25 lbs, that had dish towels or washcloths attached, too. The sacks became backing for quilts that were made from scraps of cloth leftover from making clothes. We had no large groups of dogs, so I have never seen any cloth dogfood bags. There is a material called hopsacking that was used for feed, made of course woven cotton that was popular in the late 60’s as a clothing material for mod designers of the time, that resembles burlap, but is softer and less stiff.......