Bought it for my 9yo 'puppy' after her girl surgery. She loves it. She hasn't slept but 1 other night on my cool gel pillow, if she misses me. Both of us sleep better, I toss or turned, she jumped off. She rejected2 other beds including a *** . *** foam beds which is crap compared to the cool layers on this true mattress style bed. Both cheaper beds have her hips nearly on the floor, she's all of 8lbs. I bought this in medium. She can stretch out frog legged next to me in bed, any position. Sizing: dogs do not distribute weight on haunches, that is the *** bed/ space too small