An older dog circling before it settles is usually telling you the bed is too thin. A memory foam base spreads weight instead of bottoming out under the hips and elbows, which is where arthritic dogs feel a hard floor first. Bolsters run along three sides so a dog can either stretch out flat or rest a head on the edge, and the open front means a stiff dog does not have to climb in. The cover unzips and goes in the machine, which is the part that decides whether a bed lasts a year or five. Sizes run L to XXL, so measure your dog nose to tail and add a few inches.