I bought a size M bed for my 29lb. mix pup and he fits comfortably.
The bed cover, of course, is a dream and I love that I can unzip it and wash it easily.
The bolster cushion around the sides is super supportive and firm, I just wish the bed cushion was as supportive or more since it is described as an "orthopedic" bed.
There's just not enough of the filling in the bed cushion that makes me believe it's "orthopedic".
I can feel the hardness of the floor through it and for a senior dog, that's what I was trying to avoid.
I would love to put a second bed cushion in to add more support, if possible.